We all know that Kepler will dramatically increase the detected numbers of lower-mass Earth-like planets right? We can't see such planets now because the wobble they induce in their parent's star is simply too small for our ground based equipment to differentiate.
So I'm excited that Kepler will find lots of earth-like potentials. Obviously, many of the potentials it finds probably won't have the capability to support life. Some of the stars it looks at might not have any. Others are likely to have nothing but gas giants. But as ground based surveys are showing an awful lot of the stars Kepler looks at will turn out to have significant satellite populations.
So enough blah blah blah .... I'm thinking it will find more than 1000 potential earth-like planets over the next four years.
What's your guess?
I bet at least 1.
QUOTE (Beer w/Straw+Apr 20 2009, 10:50 PM)
I bet at least 1.
But not willing to back that with an actual vote on the poll?
But not willing to back that with an actual vote on the poll?
QUOTE (uaafanblog+Apr 20 2009, 11:48 PM)
But not willing to back that with an actual vote on the poll?
I've heard some numbers crunched for Earth like planets in the universe. But other than that right now I don't have a figure, hence, "at least one" is earth inclusive.
I've heard some numbers crunched for Earth like planets in the universe. But other than that right now I don't have a figure, hence, "at least one" is earth inclusive.
QUOTE (Beer w/Straw+Apr 21 2009, 12:30 AM)
I've heard some numbers crunched for Earth like planets in the universe. But other than that right now I don't have a figure, hence, "at least one" is earth inclusive.
LOL ... then "at least 1" it is for me too.
LOL ... then "at least 1" it is for me too.
I'm going to base my answer on that movie "the day the earth stood still" 
lol. I voted 10-50, only because we have yet to meet a more advanced civilization than our own to my knowledge. I guess this doesn't rule out they may not have found us, or that any habitable planets may not have as advanced lifeforms as us.
If you take all the possibilities of sun sizes and strengths combined with the chance a planet will be the precise distance from the sun with an atmosphere to have such a regulated climate such as ours, then there has got to be at least one other planet like earth out there . I don't have any statistics though, if anyone could enlighten me please i'd be very greatful. If our universe is as infinitely large as some say, then i don't see why not, whether or not a planet like this exists within detectable range is another thing, i don't know the % chance.
I'm hopeful though
!
lol. I voted 10-50, only because we have yet to meet a more advanced civilization than our own to my knowledge. I guess this doesn't rule out they may not have found us, or that any habitable planets may not have as advanced lifeforms as us.If you take all the possibilities of sun sizes and strengths combined with the chance a planet will be the precise distance from the sun with an atmosphere to have such a regulated climate such as ours, then there has got to be at least one other planet like earth out there . I don't have any statistics though, if anyone could enlighten me please i'd be very greatful. If our universe is as infinitely large as some say, then i don't see why not, whether or not a planet like this exists within detectable range is another thing, i don't know the % chance.
I'm hopeful though
!
QUOTE (Michael J+Apr 21 2009, 03:21 AM)
I'm going to base my answer on that movie "the day the earth stood still" lol. I voted 10-50, only because we have yet to meet a more advanced civilization than our own to my knowledge. I guess this doesn't rule out they may not have found us, or that any habitable planets may not have as advanced lifeforms as us.
If you take all the possibilities of sun sizes and strengths combined with the chance a planet will be the precise distance from the sun with an atmosphere to have such a regulated climate such as ours, then there has got to be at least one other planet like earth out there . I don't have any statistics though, if anyone could enlighten me please i'd be very greatful. If our universe is as infinitely large as some say, then i don't see why not, whether or not a planet like this exists within detectable range is another thing, i don't know the % chance.
I'm hopeful though!
Be glad to flesh it out a little for you.
Kepler is going to study 100,000 stars over a four year period. Many of it's targets are already known to have satellite(s). Our ground based observations are giving us some beginning of idea of the frequency of stars with orbiting planets.
Kepler will give us enough data to know whether other stars are more or less likely to have planets. It's fine resolution will also allow it to detect many more small planets ... currently the smallest planet we can detect is about 5-10 earth masses. Kepler will allow us to identify earth sized and smaller bodies and whether or not they are in the right orbit to support any kind of biogenesis. It will not be able to determine whether any of those has any life.
The poll is not whether we think any of those will have life much less intelligent life. The best tool you can use to answer the intelligent life question isDrake's Equation.
This poll question is more about the "fp" and "Ne" variables in that equation.
By the way ... Frank Drake reports that the "average" of people making guesses puts the number of technological civilizations in our galaxy around 10,000. Remember ... that's in the 100 billion stars that are in the Milky Way. Kepler will be looking at only 100,000 in a specific portion of the sky.
lol. I voted 10-50, only because we have yet to meet a more advanced civilization than our own to my knowledge. I guess this doesn't rule out they may not have found us, or that any habitable planets may not have as advanced lifeforms as us.If you take all the possibilities of sun sizes and strengths combined with the chance a planet will be the precise distance from the sun with an atmosphere to have such a regulated climate such as ours, then there has got to be at least one other planet like earth out there . I don't have any statistics though, if anyone could enlighten me please i'd be very greatful. If our universe is as infinitely large as some say, then i don't see why not, whether or not a planet like this exists within detectable range is another thing, i don't know the % chance.
I'm hopeful though
! Be glad to flesh it out a little for you.
Kepler is going to study 100,000 stars over a four year period. Many of it's targets are already known to have satellite(s). Our ground based observations are giving us some beginning of idea of the frequency of stars with orbiting planets.
Kepler will give us enough data to know whether other stars are more or less likely to have planets. It's fine resolution will also allow it to detect many more small planets ... currently the smallest planet we can detect is about 5-10 earth masses. Kepler will allow us to identify earth sized and smaller bodies and whether or not they are in the right orbit to support any kind of biogenesis. It will not be able to determine whether any of those has any life.
The poll is not whether we think any of those will have life much less intelligent life. The best tool you can use to answer the intelligent life question isDrake's Equation.
This poll question is more about the "fp" and "Ne" variables in that equation.
By the way ... Frank Drake reports that the "average" of people making guesses puts the number of technological civilizations in our galaxy around 10,000. Remember ... that's in the 100 billion stars that are in the Milky Way. Kepler will be looking at only 100,000 in a specific portion of the sky.
Cool thanks, i'll read up on both of them!
I'll stick with my totally random guess for now until i read more
.
edit: That drake equation is amusing to fool around with...
So if kepler is studying 100,000 stars and looking to find life-worthy planets (regardless if life exists on it or not), then i guess that ups the % a lot more. But i still think there are too many possibilities (with a certain tolerance) to get too many results. Based on what i have learned about orbits and gravity in class, that would still make a supportable planet somewhat of a fluke?
Do you know what the requirements of a planet are to be classified as able to support biogenesis? I'm not quite sure what type of planet would qualify. I'm guessing one with moderate climate highs and lows, and an atmosphere, solid land and not a gas giant? But what other variables are being considered in this observation?
I'll stick with my totally random guess for now until i read more
.edit: That drake equation is amusing to fool around with...
So if kepler is studying 100,000 stars and looking to find life-worthy planets (regardless if life exists on it or not), then i guess that ups the % a lot more. But i still think there are too many possibilities (with a certain tolerance) to get too many results. Based on what i have learned about orbits and gravity in class, that would still make a supportable planet somewhat of a fluke?
Do you know what the requirements of a planet are to be classified as able to support biogenesis? I'm not quite sure what type of planet would qualify. I'm guessing one with moderate climate highs and lows, and an atmosphere, solid land and not a gas giant? But what other variables are being considered in this observation?
QUOTE (Michael J+Apr 21 2009, 04:24 AM)
Cool thanks, i'll read up on both of them!
I'll stick with my totally random guess for now until i read more.
edit: That drake equation is amusing to fool around with...
So if kepler is studying 100,000 stars and looking to find life-worthy planets (regardless if life exists on it or not), then i guess that ups the % a lot more. But i still think there are too many possibilities (with a certain tolerance) to get too many results. Based on what i have learned about orbits and gravity in class, that would still make a supportable planet somewhat of a fluke?
Do you know what the requirements of a planet are to be classified as able to support biogenesis? I'm not quite sure what type of planet would qualify. I'm guessing one with moderate climate highs and lows, and an atmosphere, solid land and not a gas giant? But what other variables are being considered in this observation?
For biogenesis it would first be necessary for there to be liquid water. It is the #1 component. To have liquid water you've got to be in the "habitable zone" (think from Venus to Mars in general).
In a few years it's hoped that NASA can launch it's planet finding interferometer called SIM at which time we'll be able to spectroscopically determine the presence of water, oxygen and possibly even methane on the exoplanets that Kepler identifies as potentials.
Here is the NASA SIM website.
I'll stick with my totally random guess for now until i read more
.edit: That drake equation is amusing to fool around with...
So if kepler is studying 100,000 stars and looking to find life-worthy planets (regardless if life exists on it or not), then i guess that ups the % a lot more. But i still think there are too many possibilities (with a certain tolerance) to get too many results. Based on what i have learned about orbits and gravity in class, that would still make a supportable planet somewhat of a fluke?
Do you know what the requirements of a planet are to be classified as able to support biogenesis? I'm not quite sure what type of planet would qualify. I'm guessing one with moderate climate highs and lows, and an atmosphere, solid land and not a gas giant? But what other variables are being considered in this observation?
For biogenesis it would first be necessary for there to be liquid water. It is the #1 component. To have liquid water you've got to be in the "habitable zone" (think from Venus to Mars in general).
In a few years it's hoped that NASA can launch it's planet finding interferometer called SIM at which time we'll be able to spectroscopically determine the presence of water, oxygen and possibly even methane on the exoplanets that Kepler identifies as potentials.
Here is the NASA SIM website.
I think we are going to find planets are very common. Also that when we start finding intelligent life, we will find some that survives where we cannot. SF authors have been speculating about non-carbon based life for many decades now.
Had to go high end, just to skew the curve.
Cheers!
MM
Cheers!
MM
QUOTE (Quatermass+Apr 21 2009, 01:19 PM)
I think we are going to find planets are very common. Also that when we start finding intelligent life, we will find some that survives where we cannot. SF authors have been speculating about non-carbon based life for many decades now.
The variable for finding intelligent life is the number of years a technological communicating civilization can endure. Can a civilization last for 10 million years? More? Way less?
That is perhaps the most important (and highly speculative) term in the Drake equation.
I'm sure I'm just biased toward the carbon molecule but there are few other elements that have it's flexibility so I'm guessing we'll find lots of fairly familiar things. But I think the "Ewwww" factor will be pretty high as well.
Imagine what we'll think when we figure out how "they" reproduce?
What if they have really bad toilet habits?
What if they subsist entirely on the fecal matter of their planets largest herbivore?
That'll gross us all out eh?
The variable for finding intelligent life is the number of years a technological communicating civilization can endure. Can a civilization last for 10 million years? More? Way less?
That is perhaps the most important (and highly speculative) term in the Drake equation.
I'm sure I'm just biased toward the carbon molecule but there are few other elements that have it's flexibility so I'm guessing we'll find lots of fairly familiar things. But I think the "Ewwww" factor will be pretty high as well.
Imagine what we'll think when we figure out how "they" reproduce?
What if they have really bad toilet habits?
What if they subsist entirely on the fecal matter of their planets largest herbivore?
That'll gross us all out eh?
QUOTE (Masked Marauder+Apr 21 2009, 03:06 PM)
Had to go high end, just to skew the curve.
Cheers!
MM
You might not be far off. That's really only saying that 10% of the stars surveyed will have 1 rocky type planet in the habitable zone.
Right now NASA says there are 344 recognized exoplanets.
So far there are two systems with rocky planets that we know of ... ours and Gilese 581 ... our solar system has 3 planets that we might detect as being in the habitable zone and Gilese has 2 it seems (the first candidates yet from from ground based observation)..
Here is a link to the astronomy and astrophysics article.
Interestingly Gilese is an M dwarf star with about one third the radius of our sun. The warm end of the habitable zone is a planet with a 12 day orbit and the cold end of the habitable zone is a planet with a 66 day orbit. The inner one is 5 earth masses and the outer is 7.7 earth masses.
Cheers!
MM
You might not be far off. That's really only saying that 10% of the stars surveyed will have 1 rocky type planet in the habitable zone.
Right now NASA says there are 344 recognized exoplanets.
So far there are two systems with rocky planets that we know of ... ours and Gilese 581 ... our solar system has 3 planets that we might detect as being in the habitable zone and Gilese has 2 it seems (the first candidates yet from from ground based observation)..
Here is a link to the astronomy and astrophysics article.
Interestingly Gilese is an M dwarf star with about one third the radius of our sun. The warm end of the habitable zone is a planet with a 12 day orbit and the cold end of the habitable zone is a planet with a 66 day orbit. The inner one is 5 earth masses and the outer is 7.7 earth masses.
I'm just bumping this in case anyone saw PBS's NovaScienceNow program last night. There was a 20+ minute profile of Kepler. It was a'ight but it included a lot of basic stuff about the history of planet searching etc ...
So ...
Bump ...
So ...
Bump ...
Yes it was a good show but i missed the last 2/3 of it.
In response to the topic, i predict there will be more than we can count. ie/ in excess of tens of thousands.
In response to the topic, i predict there will be more than we can count. ie/ in excess of tens of thousands.
I too think the number will be high. Hopefully, such findings will be exciting enough to everybody to fully fund the next generation telescope which I understand will be able to measure the spectra of each candidate planet that Kepler finds.
I certainly feel lucky to have been alive during this period in human history. I often look forward tot he future and am envious about some things that await us, but to have been alive when mankind's greatest accomplishment (walking on the Moon) occurred and looking forward to a definitive announcement of a true "Earth II" in my lifetime is pretty nice.
I certainly feel lucky to have been alive during this period in human history. I often look forward tot he future and am envious about some things that await us, but to have been alive when mankind's greatest accomplishment (walking on the Moon) occurred and looking forward to a definitive announcement of a true "Earth II" in my lifetime is pretty nice.
I said 100 to 500.
The reason for this is our own solar system has 1 planet that is in a habitable zone and 2 that are bordering that zone.
The orbits of planets tend to obey a harmonic sequence, so one would expect a planetoid in many stars "habitable zone". I figure most of these will be dwarf planets or gas giants, however.
In addition, finding 100 to 500 planets in "habitable zones' in now way implies life is on any of them. There's about a zillion other "variables" to determine whether they might have life.
The reason for this is our own solar system has 1 planet that is in a habitable zone and 2 that are bordering that zone.
The orbits of planets tend to obey a harmonic sequence, so one would expect a planetoid in many stars "habitable zone". I figure most of these will be dwarf planets or gas giants, however.
In addition, finding 100 to 500 planets in "habitable zones' in now way implies life is on any of them. There's about a zillion other "variables" to determine whether they might have life.
Does the question ask how many the Kepler Telescope will directly find, or how many will be inferred from its findings? The KT will only detect planets transiting across their sun in our line of sight. This is a rare event. If memory serves, KT will find 465 Earth-like planets... if every single star of the 100,000 has a rocky planet in the habitable zone.
Going on how the question is asked, any likely answer has to be below 1,000 to be plausible. I think it will find about 20, based on the following assumptions:
1) Most systems will form planets.
2) The current percent of known planets with stable orbits - 5% - holds more or less true across the universe, and that unstable orbits will eject their smaller planets from the system.
That would still leave several thousand earth-like planets in that field alone.
Also, be careful in assuming that every system is going to display our nice geometry of planet spacing. It could well be that only such a result will give us stable orbits, but that this result is still a bit rare. The fact that our system displays this pleasing sort of mathematics doesn't mean that it is common out there.
Going on how the question is asked, any likely answer has to be below 1,000 to be plausible. I think it will find about 20, based on the following assumptions:
1) Most systems will form planets.
2) The current percent of known planets with stable orbits - 5% - holds more or less true across the universe, and that unstable orbits will eject their smaller planets from the system.
That would still leave several thousand earth-like planets in that field alone.
Also, be careful in assuming that every system is going to display our nice geometry of planet spacing. It could well be that only such a result will give us stable orbits, but that this result is still a bit rare. The fact that our system displays this pleasing sort of mathematics doesn't mean that it is common out there.
QUOTE (uaafanblog+Apr 20 2009, 11:16 PM)
The poll is not whether we think any of those will have life much less intelligent life. The best tool you can use to answer the intelligent life question isDrake's Equation.
This poll question is more about the "fp" and "Ne" variables in that equation.
By the way ... Frank Drake reports that the "average" of people making guesses puts the number of technological civilizations in our galaxy around 10,000. Remember ... that's in the 100 billion stars that are in the Milky Way. Kepler will be looking at only 100,000 in a specific portion of the sky.
The Drake equation can also be used to determine how many Unicorns play after dark in parks:
N* = the number of parks on the Earth:
fp = fraction of parks with unicorns living near by:
Current estimates range from 100% (where Unicorns can live they do) down to close to 0%.
ne = number of parks ecologically able to entice Unicorns to play after dark:
Estimates range from 100% (Playing in the park is such a survival advantage that it will certainly evolve) down to near 0%.
fl = fraction of those parks where Unicorns actually live nearby: .
fc = the fraction of fi that has Unicorns that allow themselves to be seen:
fL = the fraction of the park's life during which these less bashful Unicorns survive:
fi = the fraction of parks where Unicorns who will allow themselves to be seen actually play after dark:
CALCULATE
N = the number of unabashed Unicorns in the world
Arthur
This poll question is more about the "fp" and "Ne" variables in that equation.
By the way ... Frank Drake reports that the "average" of people making guesses puts the number of technological civilizations in our galaxy around 10,000. Remember ... that's in the 100 billion stars that are in the Milky Way. Kepler will be looking at only 100,000 in a specific portion of the sky.
The Drake equation can also be used to determine how many Unicorns play after dark in parks:
N* = the number of parks on the Earth:
fp = fraction of parks with unicorns living near by:
Current estimates range from 100% (where Unicorns can live they do) down to close to 0%.
ne = number of parks ecologically able to entice Unicorns to play after dark:
Estimates range from 100% (Playing in the park is such a survival advantage that it will certainly evolve) down to near 0%.
fl = fraction of those parks where Unicorns actually live nearby: .
fc = the fraction of fi that has Unicorns that allow themselves to be seen:
fL = the fraction of the park's life during which these less bashful Unicorns survive:
fi = the fraction of parks where Unicorns who will allow themselves to be seen actually play after dark:
CALCULATE
N = the number of unabashed Unicorns in the world
Arthur
Arthur,
Your point besides the obvious?
Your point besides the obvious?
Only that the Drake equation can not be used as a tool to answer any question about the likelihood of intelligent life in the universe any more than it can be used to tell us how frequently one will find the elusive Unicorns playing in parks after dark.
Why?
Because we don't know the answers to ANY of the questions it asks.
Even the simplest one, as in how many stars are in the MW Galaxy:
The Milky Way system is a spiral galaxy consisting of over 400 billion stars
http://casswww.ucsd.edu/public/tutorial/MW.html
the Milky Way galaxy - a spiral galaxy of at least 200 billion stars
http://www.atlasoftheuniverse.com/galaxy.html
How many stars are in the Milky Way Galaxy?
Answer: Current estimates are 100 billion.
http://www.activemind.com/Mysterious/Topic...uation.html#Try
the Milky Way, contains maybe 400 billion stars (plus or minus 200 billion)
http://www.nova.org/~sol/chview/chv5.htm
the Milky Way, there is a predicted 3 billion to 100 billion stars.
http://hypertextbook.com/facts/2000/MarissaWager.shtml
The Milky Way is the galaxy which is the home of our Solar System together with at least 200 billion other stars (more recent estimates have given numbers around 400 billion
http://messier.obspm.fr/more/mw.html
Thus in just these few references, the number of stars in our Galaxy is estimated to be some number between 3 Billion and 600 Billion, but we have NO CLUE as to what the right number is, and it could in fact be outside of that range.
For ALL the rest of the questions, like the fraction of planets where life evolves or fraction of life where intelligent life evolves, ANY guess is as good as the next one, and thus ALL values are equally valid.
Thus NO answer is any more likely to be true than any other answer.
Arthur
Why?
Because we don't know the answers to ANY of the questions it asks.
Even the simplest one, as in how many stars are in the MW Galaxy:
The Milky Way system is a spiral galaxy consisting of over 400 billion stars
http://casswww.ucsd.edu/public/tutorial/MW.html
the Milky Way galaxy - a spiral galaxy of at least 200 billion stars
http://www.atlasoftheuniverse.com/galaxy.html
How many stars are in the Milky Way Galaxy?
Answer: Current estimates are 100 billion.
http://www.activemind.com/Mysterious/Topic...uation.html#Try
the Milky Way, contains maybe 400 billion stars (plus or minus 200 billion)
http://www.nova.org/~sol/chview/chv5.htm
the Milky Way, there is a predicted 3 billion to 100 billion stars.
http://hypertextbook.com/facts/2000/MarissaWager.shtml
The Milky Way is the galaxy which is the home of our Solar System together with at least 200 billion other stars (more recent estimates have given numbers around 400 billion
http://messier.obspm.fr/more/mw.html
Thus in just these few references, the number of stars in our Galaxy is estimated to be some number between 3 Billion and 600 Billion, but we have NO CLUE as to what the right number is, and it could in fact be outside of that range.
For ALL the rest of the questions, like the fraction of planets where life evolves or fraction of life where intelligent life evolves, ANY guess is as good as the next one, and thus ALL values are equally valid.
Thus NO answer is any more likely to be true than any other answer.
Arthur
To say we have "no clue" is a bit disingenuous. As with much science there are variable conclusions ... I'm comfortable that there are more than 3 billion stars in our Galaxy and I'm equally comfortable to say there are less than 600 billion. As with many other issues in science, we must look to consensus for the "best" answer unless and until some other data arises to reject that consensus. The accepted consensus (you may argue) is around 100 billion.
I've never seen Frank Drake (or any other reputable source) indicate that his equation was anything but full of guesses. Kepler will help us narrow down one of those parameters and aside from the broader surveys (such as those you listed) estimating the number of stars in our galaxy, yes ... they're all guesses.
Kepler will definitely give us more data about how likely other systems similar to ours exist. With the discovery of "nnn" exoplanets in the last decade (sorry ... didn't want to put an exact number since a couple of dozen are disputed), it is IMnsHO the most exciting and promising space mission we've undertaken since landing on the moon.
And yes, none of that means we're any closer to finding any intelligent life "out there" than there was yesterday. But finding a candidate planet that could actually harbor life entralls me.
I've never seen Frank Drake (or any other reputable source) indicate that his equation was anything but full of guesses. Kepler will help us narrow down one of those parameters and aside from the broader surveys (such as those you listed) estimating the number of stars in our galaxy, yes ... they're all guesses.
Kepler will definitely give us more data about how likely other systems similar to ours exist. With the discovery of "nnn" exoplanets in the last decade (sorry ... didn't want to put an exact number since a couple of dozen are disputed), it is IMnsHO the most exciting and promising space mission we've undertaken since landing on the moon.
And yes, none of that means we're any closer to finding any intelligent life "out there" than there was yesterday. But finding a candidate planet that could actually harbor life entralls me.
Any meaningful use of the Drake equation requires a significant sample size.
And the Kepler results will be one small step toward building such.
QUOTE (uaafanblog+Dec 29 2009, 08:15 PM)
To say we have "no clue" is a bit disingenuous.
No it's not,
We have no clue, and Drake's formula gets us no closer to having one.
Even if you are comfortable with the level of imprecision of the first variable being any number between 3 Billion and a number 200 times larger and even if Kepler helps us get a reasonably decent answer to the second question, the fraction of stars with planets around them.
This still leaves us with little but wild guesses for the next 5 variables, so even with good data from Kepler, any computed value from 0 to Billions is still possible and we have no way of using the equation to tell us the likelihood that any given answer is better than any other answer.
I'm not dissing the Kepler mission, just pointing out that the Drake equation is nothing more then a list of the obvious things we need to know to get the answer to the question, not a means for determining anything at the present state of knowledge.
Arthur
No it's not,
We have no clue, and Drake's formula gets us no closer to having one.
QUOTE
As with much science there are variable conclusions ... I'm comfortable that there are more than 3 billion stars in our Galaxy and I'm equally comfortable to say there are less than 600 billion. As with many other issues in science, we must look to consensus for the "best" answer unless and until some other data arises to reject that consensus. The accepted consensus (you may argue) is around 100 billion.
I've never seen Frank Drake (or any other reputable source) indicate that his equation was anything but full of guesses. Kepler will help us narrow down one of those parameters and aside from the broader surveys (such as those you listed) estimating the number of stars in our galaxy, yes ... they're all guesses.
Kepler will definitely give us more data about how likely other systems similar to ours exist. With the discovery of "nnn" exoplanets in the last decade (sorry ... didn't want to put an exact number since a couple of dozen are disputed), it is IMnsHO the most exciting and promising space mission we've undertaken since landing on the moon.
And yes, none of that means we're any closer to finding any intelligent life "out there" than there was yesterday. But finding a candidate planet that could actually harbor life entralls me.
I've never seen Frank Drake (or any other reputable source) indicate that his equation was anything but full of guesses. Kepler will help us narrow down one of those parameters and aside from the broader surveys (such as those you listed) estimating the number of stars in our galaxy, yes ... they're all guesses.
Kepler will definitely give us more data about how likely other systems similar to ours exist. With the discovery of "nnn" exoplanets in the last decade (sorry ... didn't want to put an exact number since a couple of dozen are disputed), it is IMnsHO the most exciting and promising space mission we've undertaken since landing on the moon.
And yes, none of that means we're any closer to finding any intelligent life "out there" than there was yesterday. But finding a candidate planet that could actually harbor life entralls me.
Even if you are comfortable with the level of imprecision of the first variable being any number between 3 Billion and a number 200 times larger and even if Kepler helps us get a reasonably decent answer to the second question, the fraction of stars with planets around them.
This still leaves us with little but wild guesses for the next 5 variables, so even with good data from Kepler, any computed value from 0 to Billions is still possible and we have no way of using the equation to tell us the likelihood that any given answer is better than any other answer.
I'm not dissing the Kepler mission, just pointing out that the Drake equation is nothing more then a list of the obvious things we need to know to get the answer to the question, not a means for determining anything at the present state of knowledge.
Arthur
QUOTE
No it's not,
We have no clue, and Drake's formula gets us no closer to having one.
Yes it is. "NO CLUE" is entirely disingenuous. We have PLENTY of clues. They may (as I said) be variable but there are many many many more than none; so saying "no clue" couldn't be characterized as anything other than disingenuous ... unless one perhaps calls it hyperbole. Take your choice.
QUOTE (->
| QUOTE |
No it's not, We have no clue, and Drake's formula gets us no closer to having one. |
Yes it is. "NO CLUE" is entirely disingenuous. We have PLENTY of clues. They may (as I said) be variable but there are many many many more than none; so saying "no clue" couldn't be characterized as anything other than disingenuous ... unless one perhaps calls it hyperbole. Take your choice.
Even if you are comfortable with the level of imprecision of the first variable being any number between 3 Billion and a number 200 times larger and even if Kepler helps us get a reasonably decent answer to the second question, the fraction of stars with planets around them.
This still leaves us with little but wild guesses for the next 5 variables, so even with good data from Kepler, any computed value from 0 to Billions is still possible and we have no way of using the equation to tell us the likelihood that any given answer is better than any other answer.
At the risk of repeating myself ... I said that neither Frank Drake nor any reputable person ever suggested the equation was anything but a bunch of guessing.
QUOTE
I'm not dissing the Kepler mission, just pointing out that the Drake equation is nothing more then a list of the obvious things we need to know to get the answer to the question, not a means for determining anything at the present state of knowledge.
And in context the Drake Equation only came into the discussion when a tangential question to the OP was being answered. The thread really has nothing to do with the Drake Equation (which is admittedly mental masturbation and nothing else), excepting that again, as I said, Kepler will begin to get us to a place where we can start to fill in one of the equation's variables.
QUOTE (uaafanblog+Dec 29 2009, 11:52 PM)
Yes it is. "NO CLUE" is entirely disingenuous. We have PLENTY of clues. They may (as I said) be variable but there are many many many more than none; so saying "no clue" couldn't be characterized as anything other than disingenuous ... unless one perhaps calls it hyperbole. Take your choice.
I don't think we are very much in disagreement.
You originally posted:
The point of my posts has simply been to show that as a tool it can't begin to answer that question, since with our present state of knowledge you can equally make a case for virtually ANY answer.
Which is what I mean by "No Clue".
Why?
Well regardless of your choice of inputs, no one could use FACTS to dispute you.
Because no input would be based on any known facts.
Meaning it's not a tool for anything.
For instance consider the 3nd through 5th variables:
Ne = number of planets per star ecologically able to sustain life:
While the site says the lowest number is .33, there is no basis at all for this high a number (since we have found no other planets that in fact do sustain life), and it could in fact be quite a bit lower, for instance there is the Rare Earth Hypothesis, that concludes one also needs a number of somewhat improbable other attributes in a life sustaining planet. So the reality is this number could easily be between .0001 and possibly 1.
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
or
Fl = fraction of those planets where life actually evolves.
While the site says the lowest number is .0001% , it could easily be lower. We have no idea what the likelihood of abiogenesis occurring on a given planet is, but we think that over 1 billion years passed from the time the Earth formed until the most primitive life forms arose, so at best we can assume is it takes a long while. Still a high percent of stars are over 1 billion years old, so this number could also be a many thousand times higher.
or
Fi = the fraction of Fl that evolves intelligent life
The site says the lowest number here is .0001% as well, but again it could be even lower. There is no certainty that even if abiogenesis occurs, that evolution will result in intelligent life. On the Earth, we think this took something over 3.5 billion years to occur, so at best we can assume is it also takes a long long while. Given the time frame for Fl and then Fi, a lot of bad things can occur to stop this process in its tracks. But once life started on earth, it survived some pretty nasty events, and still managed to get to the present state, so if it turns out that abiogenesis is common, then the number could also be thousands of times higher.
To put it in perspective, if all three of these turn out to be in the low end of the spectrum, then these variables alone could equate to a multiplier of .000000000000001, but if all were on the high end of the spectrum then these could be a multiplier as high as .001, or a factor of 12 greater than the low end.
So now we multiply the low value by the low end estimate of the number of stars and we get the incredibly low estimate of 0.000003 planets in the galaxy with intelligent life and multiply the high values and we get 600,000,000 planets with intelligent life.
Any formula which gives this wide of an answer is of no predictive value and we still have two more variables to consider, whose range of answers will further widen the range of possible answers.
The point of my posts has simply been to show that as a tool it can't begin to answer that question, since with our present state of knowledge you can equally make a case for virtually ANY answer.
Which is what I mean by "No Clue".
Why?
Well regardless of your choice of inputs, no one could use FACTS to dispute you.
Because no input would be based on any known facts.
Meaning it's not a tool for anything.
For instance consider the 3nd through 5th variables:
Ne = number of planets per star ecologically able to sustain life:
While the site says the lowest number is .33, there is no basis at all for this high a number (since we have found no other planets that in fact do sustain life), and it could in fact be quite a bit lower, for instance there is the Rare Earth Hypothesis, that concludes one also needs a number of somewhat improbable other attributes in a life sustaining planet. So the reality is this number could easily be between .0001 and possibly 1.
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
or
Fl = fraction of those planets where life actually evolves.
While the site says the lowest number is .0001% , it could easily be lower. We have no idea what the likelihood of abiogenesis occurring on a given planet is, but we think that over 1 billion years passed from the time the Earth formed until the most primitive life forms arose, so at best we can assume is it takes a long while. Still a high percent of stars are over 1 billion years old, so this number could also be a many thousand times higher.
or
Fi = the fraction of Fl that evolves intelligent life
The site says the lowest number here is .0001% as well, but again it could be even lower. There is no certainty that even if abiogenesis occurs, that evolution will result in intelligent life. On the Earth, we think this took something over 3.5 billion years to occur, so at best we can assume is it also takes a long long while. Given the time frame for Fl and then Fi, a lot of bad things can occur to stop this process in its tracks. But once life started on earth, it survived some pretty nasty events, and still managed to get to the present state, so if it turns out that abiogenesis is common, then the number could also be thousands of times higher.
To put it in perspective, if all three of these turn out to be in the low end of the spectrum, then these variables alone could equate to a multiplier of .000000000000001, but if all were on the high end of the spectrum then these could be a multiplier as high as .001, or a factor of 12 greater than the low end.
So now we multiply the low value by the low end estimate of the number of stars and we get the incredibly low estimate of 0.000003 planets in the galaxy with intelligent life and multiply the high values and we get 600,000,000 planets with intelligent life.
Any formula which gives this wide of an answer is of no predictive value and we still have two more variables to consider, whose range of answers will further widen the range of possible answers.
I said that neither Frank Drake nor any reputable person ever suggested the equation was anything but a bunch of guessing.
Which I'm in agreement with, which is why I disagreed with the "tool" reference.
I agree, but as shown above, even with the first two variables filled in, the equation is still useless.
Arthur
I don't think we are very much in disagreement.
You originally posted:
QUOTE
The best tool you can use to answer the intelligent life question is Drake's Equation
The point of my posts has simply been to show that as a tool it can't begin to answer that question, since with our present state of knowledge you can equally make a case for virtually ANY answer.
Which is what I mean by "No Clue".
Why?
Well regardless of your choice of inputs, no one could use FACTS to dispute you.
Because no input would be based on any known facts.
Meaning it's not a tool for anything.
For instance consider the 3nd through 5th variables:
Ne = number of planets per star ecologically able to sustain life:
While the site says the lowest number is .33, there is no basis at all for this high a number (since we have found no other planets that in fact do sustain life), and it could in fact be quite a bit lower, for instance there is the Rare Earth Hypothesis, that concludes one also needs a number of somewhat improbable other attributes in a life sustaining planet. So the reality is this number could easily be between .0001 and possibly 1.
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
or
Fl = fraction of those planets where life actually evolves.
While the site says the lowest number is .0001% , it could easily be lower. We have no idea what the likelihood of abiogenesis occurring on a given planet is, but we think that over 1 billion years passed from the time the Earth formed until the most primitive life forms arose, so at best we can assume is it takes a long while. Still a high percent of stars are over 1 billion years old, so this number could also be a many thousand times higher.
or
Fi = the fraction of Fl that evolves intelligent life
The site says the lowest number here is .0001% as well, but again it could be even lower. There is no certainty that even if abiogenesis occurs, that evolution will result in intelligent life. On the Earth, we think this took something over 3.5 billion years to occur, so at best we can assume is it also takes a long long while. Given the time frame for Fl and then Fi, a lot of bad things can occur to stop this process in its tracks. But once life started on earth, it survived some pretty nasty events, and still managed to get to the present state, so if it turns out that abiogenesis is common, then the number could also be thousands of times higher.
To put it in perspective, if all three of these turn out to be in the low end of the spectrum, then these variables alone could equate to a multiplier of .000000000000001, but if all were on the high end of the spectrum then these could be a multiplier as high as .001, or a factor of 12 greater than the low end.
So now we multiply the low value by the low end estimate of the number of stars and we get the incredibly low estimate of 0.000003 planets in the galaxy with intelligent life and multiply the high values and we get 600,000,000 planets with intelligent life.
Any formula which gives this wide of an answer is of no predictive value and we still have two more variables to consider, whose range of answers will further widen the range of possible answers.
QUOTE (->
| QUOTE |
| The best tool you can use to answer the intelligent life question is Drake's Equation |
The point of my posts has simply been to show that as a tool it can't begin to answer that question, since with our present state of knowledge you can equally make a case for virtually ANY answer.
Which is what I mean by "No Clue".
Why?
Well regardless of your choice of inputs, no one could use FACTS to dispute you.
Because no input would be based on any known facts.
Meaning it's not a tool for anything.
For instance consider the 3nd through 5th variables:
Ne = number of planets per star ecologically able to sustain life:
While the site says the lowest number is .33, there is no basis at all for this high a number (since we have found no other planets that in fact do sustain life), and it could in fact be quite a bit lower, for instance there is the Rare Earth Hypothesis, that concludes one also needs a number of somewhat improbable other attributes in a life sustaining planet. So the reality is this number could easily be between .0001 and possibly 1.
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
or
Fl = fraction of those planets where life actually evolves.
While the site says the lowest number is .0001% , it could easily be lower. We have no idea what the likelihood of abiogenesis occurring on a given planet is, but we think that over 1 billion years passed from the time the Earth formed until the most primitive life forms arose, so at best we can assume is it takes a long while. Still a high percent of stars are over 1 billion years old, so this number could also be a many thousand times higher.
or
Fi = the fraction of Fl that evolves intelligent life
The site says the lowest number here is .0001% as well, but again it could be even lower. There is no certainty that even if abiogenesis occurs, that evolution will result in intelligent life. On the Earth, we think this took something over 3.5 billion years to occur, so at best we can assume is it also takes a long long while. Given the time frame for Fl and then Fi, a lot of bad things can occur to stop this process in its tracks. But once life started on earth, it survived some pretty nasty events, and still managed to get to the present state, so if it turns out that abiogenesis is common, then the number could also be thousands of times higher.
To put it in perspective, if all three of these turn out to be in the low end of the spectrum, then these variables alone could equate to a multiplier of .000000000000001, but if all were on the high end of the spectrum then these could be a multiplier as high as .001, or a factor of 12 greater than the low end.
So now we multiply the low value by the low end estimate of the number of stars and we get the incredibly low estimate of 0.000003 planets in the galaxy with intelligent life and multiply the high values and we get 600,000,000 planets with intelligent life.
Any formula which gives this wide of an answer is of no predictive value and we still have two more variables to consider, whose range of answers will further widen the range of possible answers.
I said that neither Frank Drake nor any reputable person ever suggested the equation was anything but a bunch of guessing.
Which I'm in agreement with, which is why I disagreed with the "tool" reference.
QUOTE
The thread really has nothing to do with the Drake Equation (which is admittedly mental masturbation and nothing else), excepting that again, as I said, Kepler will begin to get us to a place where we can start to fill in one of the equation's variables.
I agree, but as shown above, even with the first two variables filled in, the equation is still useless.
Arthur
As you say, there's no real disagreement here then. Though I do think we differ with regard to the use of the word "tool". I think it is one. It's just that it's a tool for speculation. That said, allow me to add a few thoughts.
In one sense, "Rare Earth" is not much more than an intellectual pissing on Drake's parade. It acts as a reasonable counter-argument. All well and good.
Essentially, it comes down to optimism versus pessimism or perhaps more accurately hope versus skepticism. I'm obviously in the "sure would be a waste of space" camp and I think it's safe to characterize you as skeptical. Either view (at this point) could be "more" correct than the other.
I will say that I'm skeptical that any discovery of intelligent life will come relatively soon. So I don't sit around with my fingers crossed anticipating such an event. On the other hand though, my fingers are crossed that we get some positive indication of relatively nearby potentially habitable earth-analogue during my lifetime. Kepler probably won't reveal such a candidate but it is likely to give us many targets to investigate with the next generation devices that are planned to follow it.
In one sense, "Rare Earth" is not much more than an intellectual pissing on Drake's parade. It acts as a reasonable counter-argument. All well and good.
Essentially, it comes down to optimism versus pessimism or perhaps more accurately hope versus skepticism. I'm obviously in the "sure would be a waste of space" camp and I think it's safe to characterize you as skeptical. Either view (at this point) could be "more" correct than the other.
I will say that I'm skeptical that any discovery of intelligent life will come relatively soon. So I don't sit around with my fingers crossed anticipating such an event. On the other hand though, my fingers are crossed that we get some positive indication of relatively nearby potentially habitable earth-analogue during my lifetime. Kepler probably won't reveal such a candidate but it is likely to give us many targets to investigate with the next generation devices that are planned to follow it.
I don't know what you mean by "relatively nearby".
In cosmic terms that can mean some pretty far distances.
Yes, I'm very skeptical.
I believe that most of the Rare Earth hypothesis is likely to be true, to varying degrees, such that the likelihood that we will ever find evidence of life on another planet is remote and that we will ever encounter intelligent life is next to nothing.
Nor do I believe that we will ever send a probe to another planet with the ability to tell us what it finds there, simply because even to the nearest star the mission would be monumentally expensive and even then would likely take far longer than a human lifetime to accomplish. Damn hard to get funding for a mission when no one alive will ever see the results.
It's highly unlikely that anything Kepler finds will alter this, as less than 1% of the stars it's looking at are less than 600 LY from earth.
Kepler has been looking at the star field for almost a year and AFAIK, hasn't found any new planets (it did look a bit closer at one that we already knew about).
This is somewhat disappointing considering their expected results:
Expected Results
The Kepler Mission begins to collect data immediately after launch and checkout and begins to produce results in a progressive fashion shortly thereafter.
The first results come in just a few months when the giant inner planets are seen, those with orbital periods of only a few days.
Objects that are in Mercury-like orbits of a few months are detected within the first year.
http://kepler.nasa.gov/sci/basis/results.html
Arthur
In cosmic terms that can mean some pretty far distances.
Yes, I'm very skeptical.
I believe that most of the Rare Earth hypothesis is likely to be true, to varying degrees, such that the likelihood that we will ever find evidence of life on another planet is remote and that we will ever encounter intelligent life is next to nothing.
Nor do I believe that we will ever send a probe to another planet with the ability to tell us what it finds there, simply because even to the nearest star the mission would be monumentally expensive and even then would likely take far longer than a human lifetime to accomplish. Damn hard to get funding for a mission when no one alive will ever see the results.
It's highly unlikely that anything Kepler finds will alter this, as less than 1% of the stars it's looking at are less than 600 LY from earth.
Kepler has been looking at the star field for almost a year and AFAIK, hasn't found any new planets (it did look a bit closer at one that we already knew about).
This is somewhat disappointing considering their expected results:
Expected Results
The Kepler Mission begins to collect data immediately after launch and checkout and begins to produce results in a progressive fashion shortly thereafter.
The first results come in just a few months when the giant inner planets are seen, those with orbital periods of only a few days.
Objects that are in Mercury-like orbits of a few months are detected within the first year.
http://kepler.nasa.gov/sci/basis/results.html
Arthur
The Kepler scientists are going to make an announcement in January of what they have found so far. Apparently, they have found some things, and some of what they have found, to paraphrase one of them, is beyond anything he had expected or could have predicted. I am keen to see what it could be.
As for the Drake Equation, I think the best description is that it is a good way to organize our ignorance. That doesn't make it any less fun.
And I think the Rare Earth Hypothesis is probably not far from the truth.
As for the Drake Equation, I think the best description is that it is a good way to organize our ignorance. That doesn't make it any less fun.
And I think the Rare Earth Hypothesis is probably not far from the truth.
"Relatively nearby" means that in relation to the expanse of the galaxy that even 600 light years is nearby. Relative is a pretty common term that I wouldn't have expected to be questioned using in this place ... but whatev ...
Sending a probe to something even more "relatively nearby" won't necessarily be such a big task. Technologically, we're not that far from being able to do so. In 50 years or so who's to say that we won't be capable of driving something as high as .2 or .3 of c. Perhaps VASIMR (or some future variant) will be capable.
As to Kepler's results. Your assertion that the telescope has been "looking at the star field for almost a year" is specious and once again it's disingenuous for you to phrase it that way. It's mission phase began last MAY 12th. By my reckoning (and I'm not good at math) that's more than 100 days short of a year.
Since Kepler uses the transit method we can't expect any "wow" results for a couple of more years since those "wow" planets will be in long orbits. They are requiring a minimum of three transit detections.
The first set of results are currently being compiled and are expected to be announced within a week ... on January 4th. Again, I wouldn't expect anything hugely compelling but I would be surprised if they didn't both refine some existing exoplanet knowledge as well as announce some new discoveries. From everything I've seen (and I have been following it) they're taking an overall conservative approach (probably for political reasons within the astronomy community).
In any case, I'll summarize and link to the first set of results in this thread after they come out.
At this point I'd rescind the skeptical label and instead apply one of pessimism with regard to your views here. Try to get back up to skeptical eh? I mean seriously, we're not talking climate change datasets here.
Aside from cataloguing exoplanets Kepler has a secondary mission to categorize star types etc. It's a damn good piece of technology and while it isn't likely to have the same "cachet" as HST, it will fill an important gap in some of our knowledge about the cosmos. It's intended to be an initial step.
Sending a probe to something even more "relatively nearby" won't necessarily be such a big task. Technologically, we're not that far from being able to do so. In 50 years or so who's to say that we won't be capable of driving something as high as .2 or .3 of c. Perhaps VASIMR (or some future variant) will be capable.
As to Kepler's results. Your assertion that the telescope has been "looking at the star field for almost a year" is specious and once again it's disingenuous for you to phrase it that way. It's mission phase began last MAY 12th. By my reckoning (and I'm not good at math) that's more than 100 days short of a year.
Since Kepler uses the transit method we can't expect any "wow" results for a couple of more years since those "wow" planets will be in long orbits. They are requiring a minimum of three transit detections.
The first set of results are currently being compiled and are expected to be announced within a week ... on January 4th. Again, I wouldn't expect anything hugely compelling but I would be surprised if they didn't both refine some existing exoplanet knowledge as well as announce some new discoveries. From everything I've seen (and I have been following it) they're taking an overall conservative approach (probably for political reasons within the astronomy community).
In any case, I'll summarize and link to the first set of results in this thread after they come out.
At this point I'd rescind the skeptical label and instead apply one of pessimism with regard to your views here. Try to get back up to skeptical eh? I mean seriously, we're not talking climate change datasets here.
Aside from cataloguing exoplanets Kepler has a secondary mission to categorize star types etc. It's a damn good piece of technology and while it isn't likely to have the same "cachet" as HST, it will fill an important gap in some of our knowledge about the cosmos. It's intended to be an initial step.
QUOTE (uaafanblog+Dec 30 2009, 06:35 PM)
"Relatively nearby" means that in relation to the expanse of the galaxy that even 600 light years is nearby. Relative is a pretty common term that I wouldn't have expected to be questioned using in this place ... but whatev ...
Just checking, again with vast distances, the term "nearby" can mean different things to different people.
Well I don't think we are anywhere near being able to do so and so to me that's a huge exaggeration of our present capabilities and plans.
To put it in perspective, The VASIMR still goes through a LOT of fuel to not go very far or very fast.
Well I don't think we are anywhere near being able to do so and so to me that's a huge exaggeration of our present capabilities and plans.
To put it in perspective, The VASIMR still goes through a LOT of fuel to not go very far or very fast.
An OTV (space tug) powered by a single VF-200 engine would be capable of transporting about 7 metric tons of cargo from Low Earth Orbit (LEO) to Low Lunar Orbit (LLO) with about a six month long transit time. A comparable OTV would need to employ 5 VF-200 engines powered by a 1 MW solar array. To do the same job, such OTV would need to expend only about 8 metric tonnes of argon propellant.
Of course, on an interstellar flight, the use of the solar array is not viable.
Nor is the use of 8 tons of fuel to get 7 tons of cargo from LEO to LLO very promising.
The fact is, besides the probe itself, one is constrained by sheer mass of the fuel needed, even at very high efficiencies.
Consider that if you have enough fuel to accelerate to .2 c (134 million mph), you need the fuel to decelerate as well, and you have to take all that fuel with you to start. All that mass would mean it would probably take decades to accelerate to even .1c, so we are looking at a trip that's likely to take nearly 100 years.
Sure anything is possible in the future, but I still find it highly unlikely that this trip will ever happen due to its incredible cost and complexity and thus low likelihood of providing anything of significant value to the people who would have to fund it.
Well I guess I think 8 months is almost a year, and I did post only the first two near term results that they were looking for:
As they said:
Well I guess I think 8 months is almost a year, and I did post only the first two near term results that they were looking for:
As they said:
The Kepler Mission begins to collect data immediately after launch and checkout and begins to produce results in a progressive fashion shortly thereafter.
The first results come in just a few months when the giant inner planets are seen, those with orbital periods of only a few days.
Objects that are in Mercury-like orbits of a few months are detected within the first year.
So they certainly set the expectation that there would be results within a FEW MONTHS and that planets with Mercury like orbits would be detected WITHIN the first year. One would have expected that planets with transit times of 2 or 3 months would have been seen several times by now.
So, YES, I had been expecting something besides silence from them by now.
Hopefully gocrew is right and they will soon release info "beyond anything NASA had expected or could have predicted"
Well you two must have an inside source, because there's nothing on the Kepler Web site that hints at any of that.
http://kepler.nasa.gov/about/news.html
I can only post on what is publicly available.
Again, I hope you are right.
Well you two must have an inside source, because there's nothing on the Kepler Web site that hints at any of that.
http://kepler.nasa.gov/about/news.html
I can only post on what is publicly available.
Again, I hope you are right.
At this point I'd rescind the skeptical label and instead apply one of pessimism with regard to your views here. Try to get back up to skeptical eh? I mean seriously, we're not talking climate change datasets here.
And I think I'm just being realistic.
Arthur
Just checking, again with vast distances, the term "nearby" can mean different things to different people.
QUOTE
Sending a probe to something even more "relatively nearby" won't necessarily be such a big task. Technologically, we're not that far from being able to do so. In 50 years or so who's to say that we won't be capable of driving something as high as .2 or .3 of c. Perhaps VASIMR (or some future variant) will be capable.
Well I don't think we are anywhere near being able to do so and so to me that's a huge exaggeration of our present capabilities and plans.
To put it in perspective, The VASIMR still goes through a LOT of fuel to not go very far or very fast.
QUOTE (->
| QUOTE |
| Sending a probe to something even more "relatively nearby" won't necessarily be such a big task. Technologically, we're not that far from being able to do so. In 50 years or so who's to say that we won't be capable of driving something as high as .2 or .3 of c. Perhaps VASIMR (or some future variant) will be capable. |
Well I don't think we are anywhere near being able to do so and so to me that's a huge exaggeration of our present capabilities and plans.
To put it in perspective, The VASIMR still goes through a LOT of fuel to not go very far or very fast.
An OTV (space tug) powered by a single VF-200 engine would be capable of transporting about 7 metric tons of cargo from Low Earth Orbit (LEO) to Low Lunar Orbit (LLO) with about a six month long transit time. A comparable OTV would need to employ 5 VF-200 engines powered by a 1 MW solar array. To do the same job, such OTV would need to expend only about 8 metric tonnes of argon propellant.
Of course, on an interstellar flight, the use of the solar array is not viable.
Nor is the use of 8 tons of fuel to get 7 tons of cargo from LEO to LLO very promising.
The fact is, besides the probe itself, one is constrained by sheer mass of the fuel needed, even at very high efficiencies.
Consider that if you have enough fuel to accelerate to .2 c (134 million mph), you need the fuel to decelerate as well, and you have to take all that fuel with you to start. All that mass would mean it would probably take decades to accelerate to even .1c, so we are looking at a trip that's likely to take nearly 100 years.
Sure anything is possible in the future, but I still find it highly unlikely that this trip will ever happen due to its incredible cost and complexity and thus low likelihood of providing anything of significant value to the people who would have to fund it.
QUOTE
As to Kepler's results. Your assertion that the telescope has been "looking at the star field for almost a year" is specious and once again it's disingenuous for you to phrase it that way. It's mission phase began last MAY 12th. By my reckoning (and I'm not good at math) that's more than 100 days short of a year.
Well I guess I think 8 months is almost a year, and I did post only the first two near term results that they were looking for:
As they said:
QUOTE (->
| QUOTE |
| As to Kepler's results. Your assertion that the telescope has been "looking at the star field for almost a year" is specious and once again it's disingenuous for you to phrase it that way. It's mission phase began last MAY 12th. By my reckoning (and I'm not good at math) that's more than 100 days short of a year. |
Well I guess I think 8 months is almost a year, and I did post only the first two near term results that they were looking for:
As they said:
The Kepler Mission begins to collect data immediately after launch and checkout and begins to produce results in a progressive fashion shortly thereafter.
The first results come in just a few months when the giant inner planets are seen, those with orbital periods of only a few days.
Objects that are in Mercury-like orbits of a few months are detected within the first year.
So they certainly set the expectation that there would be results within a FEW MONTHS and that planets with Mercury like orbits would be detected WITHIN the first year. One would have expected that planets with transit times of 2 or 3 months would have been seen several times by now.
So, YES, I had been expecting something besides silence from them by now.
Hopefully gocrew is right and they will soon release info "beyond anything NASA had expected or could have predicted"
QUOTE
Since Kepler uses the transit method we can't expect any "wow" results for a couple of more years since those "wow" planets will be in long orbits. They are requiring a minimum of three transit detections.
The first set of results are currently being compiled and are expected to be announced within a week ... on January 4th. Again, I wouldn't expect anything hugely compelling but I would be surprised if they didn't both refine some existing exoplanet knowledge as well as announce some new discoveries. From everything I've seen (and I have been following it) they're taking an overall conservative approach (probably for political reasons within the astronomy community).
In any case, I'll summarize and link to the first set of results in this thread after they come out.
The first set of results are currently being compiled and are expected to be announced within a week ... on January 4th. Again, I wouldn't expect anything hugely compelling but I would be surprised if they didn't both refine some existing exoplanet knowledge as well as announce some new discoveries. From everything I've seen (and I have been following it) they're taking an overall conservative approach (probably for political reasons within the astronomy community).
In any case, I'll summarize and link to the first set of results in this thread after they come out.
Well you two must have an inside source, because there's nothing on the Kepler Web site that hints at any of that.
http://kepler.nasa.gov/about/news.html
I can only post on what is publicly available.
Again, I hope you are right.
QUOTE (->
| QUOTE |
| Since Kepler uses the transit method we can't expect any "wow" results for a couple of more years since those "wow" planets will be in long orbits. They are requiring a minimum of three transit detections. The first set of results are currently being compiled and are expected to be announced within a week ... on January 4th. Again, I wouldn't expect anything hugely compelling but I would be surprised if they didn't both refine some existing exoplanet knowledge as well as announce some new discoveries. From everything I've seen (and I have been following it) they're taking an overall conservative approach (probably for political reasons within the astronomy community). In any case, I'll summarize and link to the first set of results in this thread after they come out. |
Well you two must have an inside source, because there's nothing on the Kepler Web site that hints at any of that.
http://kepler.nasa.gov/about/news.html
I can only post on what is publicly available.
Again, I hope you are right.
At this point I'd rescind the skeptical label and instead apply one of pessimism with regard to your views here. Try to get back up to skeptical eh? I mean seriously, we're not talking climate change datasets here.
And I think I'm just being realistic.
Arthur
QUOTE (adoucette+Dec 30 2009, 06:41 PM)
To put it in perspective, The VASIMR still goes through a LOT of fuel to not go very far or very fast.
Of course, on an interstellar flight, the use of the solar array is not viable.
Nor is the use of 8 tons of fuel to get 7 tons of cargo from LEO to LLO very promising.
The fact is, besides the probe itself, one is constrained by sheer mass of the fuel needed, even at very high efficiencies.
Consider that if you have enough fuel to accelerate to .2 c (134 million mph), you need the fuel to decelerate as well, and you have to take all that fuel with you to start. All that mass would mean it would probably take decades to accelerate to even .1c, so we are looking at a trip that's likely to take nearly 100 years.
There are speculated configurations that include harvesting fuel (hydrogen) from the interstellar medium during transit. Obviously, the density of hydrogen is pretty low out there but perhaps that would be possible. I'd envision starting with the maximum amount possible. When you consider the lift capabilities of the Ares rocket plus perhaps staging additional fuel in orbit and then supplemental in-transit collection then perhaps it's all possible. And yes ... 100 years or more would certainly be the neighborhood we're talking about.
Is that a reasonable time frame? Perhaps not. It could be that by the time the probe got to the halfway point you've found a drive system to go .5c which would mean you could launch it 50 years after you launched your first one and get there first. Such considerations are necessary.
I tend toward hoping that the enthusiasm generated from knowing there is a planet out there with sufficient water and oxygen in a good orbit around a stable star that would spur investment to make something happen. The closer such a destination is the better obviously. I'm of the opinion that there's a good reason that we humans have a genetic predisposition to push frontier boundaries. It has served us well to this point in our history and I fully believe it will serve us well in the future. There are clearly no candidates to fill that need in our system ... so we're going to have to figure out a way to make it happen in the future. Perhaps that means slow moving generational ships as a follow-on to the probe mission.
In any case, as you see ... I'm fully optimistic about the possibilities and (for now at least) will continue to hope that some good possibility arises. I'd like to take my dirt nap with the knowledge that some first step to interstellar travel is either happening or in the works. I estimate at most I've got another 50 years before I lay down in the ground. So I'm itching for them to get it on at the earliest possible time.
Of course, on an interstellar flight, the use of the solar array is not viable.
Nor is the use of 8 tons of fuel to get 7 tons of cargo from LEO to LLO very promising.
The fact is, besides the probe itself, one is constrained by sheer mass of the fuel needed, even at very high efficiencies.
Consider that if you have enough fuel to accelerate to .2 c (134 million mph), you need the fuel to decelerate as well, and you have to take all that fuel with you to start. All that mass would mean it would probably take decades to accelerate to even .1c, so we are looking at a trip that's likely to take nearly 100 years.
There are speculated configurations that include harvesting fuel (hydrogen) from the interstellar medium during transit. Obviously, the density of hydrogen is pretty low out there but perhaps that would be possible. I'd envision starting with the maximum amount possible. When you consider the lift capabilities of the Ares rocket plus perhaps staging additional fuel in orbit and then supplemental in-transit collection then perhaps it's all possible. And yes ... 100 years or more would certainly be the neighborhood we're talking about.
Is that a reasonable time frame? Perhaps not. It could be that by the time the probe got to the halfway point you've found a drive system to go .5c which would mean you could launch it 50 years after you launched your first one and get there first. Such considerations are necessary.
I tend toward hoping that the enthusiasm generated from knowing there is a planet out there with sufficient water and oxygen in a good orbit around a stable star that would spur investment to make something happen. The closer such a destination is the better obviously. I'm of the opinion that there's a good reason that we humans have a genetic predisposition to push frontier boundaries. It has served us well to this point in our history and I fully believe it will serve us well in the future. There are clearly no candidates to fill that need in our system ... so we're going to have to figure out a way to make it happen in the future. Perhaps that means slow moving generational ships as a follow-on to the probe mission.
In any case, as you see ... I'm fully optimistic about the possibilities and (for now at least) will continue to hope that some good possibility arises. I'd like to take my dirt nap with the knowledge that some first step to interstellar travel is either happening or in the works. I estimate at most I've got another 50 years before I lay down in the ground. So I'm itching for them to get it on at the earliest possible time.
QUOTE (uaafanblog+Dec 30 2009, 11:48 PM)
I tend toward hoping that the enthusiasm generated from knowing there is a planet out there with sufficient water and oxygen in a good orbit around a stable star that would spur investment to make something happen.
I think that's a very necessary pre-req for such a mission, but the other one is equally critical.
Distance.
I think that's a very necessary pre-req for such a mission, but the other one is equally critical.
Distance.
QUOTE (uaafanblog+)
The closer such a destination is the better obviously.
But there just aren't that many stars that close to us that are likely to fill the pre-req.
In fact there are only 6 yellow suns within 20 LYs of Earth, but 2 of those are binary stars and so are not suitable.
http://www.atlasoftheuniverse.com/20lys.html
Since I think it HIGHLY unlikely that we would ever manage a mission with an average speed greater than 0.1 c, and since it's not likely the planet you are looking for is closer than 20 LYs, so the shortest this mission is likely to be is a 200+ year mission.
At which point I think it's reasonable to ask, what's the point?
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
Several dozen to less than 100 unique individuals, perferably inter-racial couples as they would have solved the "race" problem.
Several dozen to less than 100 unique individuals, perferably inter-racial couples as they would have solved the "race" problem.
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and the food and water (and plants and animals?) and tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
You assume they need to land right away. This isn't necessarily the case. They may be able to construct a landing vehicle or additional self-sustained Dyson Structures from asteroids and small moons in the vacinity, before ever landing on the target planet.
This is definitely wrong numbers. You are likely making some sort of mistake like I did the first several times I tried to understand anti-matter and nuclear propulsion.
A FIVE PERCENT efficient anti-matter drive requires far less fuel mass than the ship's mass, and has a maximum velocity of at least 0.8c.
You can get this from E=2MC^2 (where "M" is the mass of anti-matter, and is doubled by the mass of the matter component of fuel) and then calculate to convert this to momentum of the ship, then factor velocity.
0.5kg matter + 0.5kg anti-matter yields:
1kg*c^2 = 9*10^16 kg*m^2/s^2
Which if you do the math, should put the space shuttle insanely close to light speed, even with relativistic effects. like 0.999999c...
Less than half a Kilogram of antimatter is enough to accelerate the space shuttle to very near light speed, to within maximum theoretical limits of antimatter drives, which are commonly reported as at least 0.8c. Though honestly, I think the number is arbitrarily close to c, because nobody has ever given a reason why 0.8c should be a limit if you are carrying larger amount of anti-matter, since acceleration and velocity are themselves relative.
A FIFTY PERCENT efficient fusion drive would require about as much fuel mass as the ship's mass (to within reasonable scale factors relative to the engine's minimum or maximum safe size). This is to obtain the maximum theoretical velocity of a fusion ship.
This is definitely wrong numbers. You are likely making some sort of mistake like I did the first several times I tried to understand anti-matter and nuclear propulsion.
A FIVE PERCENT efficient anti-matter drive requires far less fuel mass than the ship's mass, and has a maximum velocity of at least 0.8c.
You can get this from E=2MC^2 (where "M" is the mass of anti-matter, and is doubled by the mass of the matter component of fuel) and then calculate to convert this to momentum of the ship, then factor velocity.
0.5kg matter + 0.5kg anti-matter yields:
1kg*c^2 = 9*10^16 kg*m^2/s^2
Which if you do the math, should put the space shuttle insanely close to light speed, even with relativistic effects. like 0.999999c...
Less than half a Kilogram of antimatter is enough to accelerate the space shuttle to very near light speed, to within maximum theoretical limits of antimatter drives, which are commonly reported as at least 0.8c. Though honestly, I think the number is arbitrarily close to c, because nobody has ever given a reason why 0.8c should be a limit if you are carrying larger amount of anti-matter, since acceleration and velocity are themselves relative.
A FIFTY PERCENT efficient fusion drive would require about as much fuel mass as the ship's mass (to within reasonable scale factors relative to the engine's minimum or maximum safe size). This is to obtain the maximum theoretical velocity of a fusion ship.
Final note, the generational arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have been started by Ferdinand and Isabella.
Why everyone in modern times considers generational projects as "impossible" or "pointless" is beyond me.
In ancient times people constructed generational projects in nearly every major civilization, in many cases having no real function in terms of resources.
We construct "useless" semi-generational structures all the time and don't even think about it. We call them "Sports Arenas" and while they technically "pay" for themselves in dollars, at least to the owner, they have no "real" economic value, because they do not produce goods or energy.
Yeah, well that's a problem though isn't it.
Roughly speaking it takes about 25,000 sq ft at an absolute MINIMUM of FERTILE land and good sun and good rain to feed a person for a year.
In space, where we don't have seasons, let's cut that in HALF, and say we can get by on 12,500 sq ft of space, which is over 250 acres of intense crops and animals you have to heat, light, water and manage.
Which is just ONE of the reasons you won't get by with just your 800 people.
Farming, food preservation, animal husbandry and packaging would take a lot of manpower just by itself
There are just too many skills needed to keep a totally self reliant super high tech vessel going for 200+ years to be handled by just 800 people. Considering the number that are too old and too young to contribute, but require care, and an amazing amount of care and time expended on the young, who have to be raised and then taught on a HIGH PRESSURE curriculum to take over as the next generation.
Arthur
This was discussed by myself and others previously. With existing transmitter technology you would need a relay of probes due to signal degradation. So in order to probe a planet at 20ly, you need about 15-20 relays a lightyear or so distant from one another, OR you need one probe with a VERY powerful laser-based transmitter. It also needs redundant backups of the transmitter in case of a mechanical malfunction OR self repairing mechanisms...but then...the self repair mechanisms need backups too...(nano-robots.)
This was discussed by myself and others previously. With existing transmitter technology you would need a relay of probes due to signal degradation. So in order to probe a planet at 20ly, you need about 15-20 relays a lightyear or so distant from one another, OR you need one probe with a VERY powerful laser-based transmitter. It also needs redundant backups of the transmitter in case of a mechanical malfunction OR self repairing mechanisms...but then...the self repair mechanisms need backups too...(nano-robots.)
Oh, and the generational craft's arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have to have been started by Ferdinand and Isabella.
Yet, Columbus sailed across the atlantic using technology so relatively primitive compared to modern standards, that most of us have FORGOTTEN how to even make a ship that primitive...
===
Ok, so anyone who is advanced enough to make such a probe, and to make a generational ship as here described, would no longer need a planet to live on in the first place. Such a civilization would simply need enough material at the destination star to make Dyson Swarms, and they may actually be better served looking for stars that don't have planets at all, but rather stars with very large belts of asteroids and comets which can be easily harvested to produce new artificial environments.
After all, if you've solved the problem of a ~200-300 year voyage through space, landing the colony ship on the surface of a planet is a dumb move and a waste of energy(not that energy would even matter much, I suppose.) As having survived without a planet for 200-300 years, it would certainly have met or exceeded the needs of my orbital platforms, and could then continue to serve in that function for a new Type 2 Dyson Swarm civilization at the new star, without the need for a planet anyway.
So if you can't build a "self sustaining" orbital platform or Dyson Swarm that survives by solar power and mining asteroids and comets, then you definitely cannot build an interstellar colony ship that survives by anti-matter power...
The Dyson Swarm is absolutely a pre-requisite for making a colony ship, because it shares every technology except possibly propulsion and on-board power.
This was discussed by myself and others previously. With existing transmitter technology you would need a relay of probes due to signal degradation. So in order to probe a planet at 20ly, you need about 15-20 relays a lightyear or so distant from one another, OR you need one probe with a VERY powerful laser-based transmitter. It also needs redundant backups of the transmitter in case of a mechanical malfunction OR self repairing mechanisms...but then...the self repair mechanisms need backups too...(nano-robots.)
Too risky.
Lose one, lose them all.
And NO, you couldn't expect it to repair itself.
The safe bet is the ONE BIG transmitter, but that just adds to the weight and complexity of the probe.
Which is what you don't want.
Face it, you won't hear a peep from this thing after its a few LYs from earth.
To put it in perspective, it takes quite a bit to still pick up Voyager, but its only ~ 100 AU from earth.
A light year is over 63,000 AU.
Arthur
Yeah, well that's a problem though isn't it.
Roughly speaking it takes about 25,000 sq ft at an absolute MINIMUM of FERTILE land and good sun and good rain to feed a person for a year.
In space, where we don't have seasons, let's cut that in HALF, and say we can get by on 12,500 sq ft of space, which is over 250 acres of intense crops and animals you have to heat, light, water and manage.
Which is just ONE of the reasons you won't get by with just your 800 people.
Farming, food preservation, animal husbandry and packaging would take a lot of manpower just by itself
There are just too many skills needed to keep a totally self reliant super high tech vessel going for 200+ years to be handled by just 800 people. Considering the number that are too old and too young to contribute, but require care, and an amazing amount of care and time expended on the young, who have to be raised and then taught on a HIGH PRESSURE curriculum to take over as the next generation.
Arthur
I'm not downplaying the issue, but most plants in nature, including our primary crops, are not terribly efficient in open fields. Tomatoes in modern greenhouses grow as much as 16 times more marketable food content. In addition, due to shipping reasons, everything except the absolute best tomatoes are thrown away, even though most of the discarded food is edible and could be canned if there was a cannery on site...
I have seen demonstrations on growing sweet potatoes and peanuts which show that they can be grown in a nutrient solution with no soil at all, and possibly for a lower price per yield than traditional farming, (which is why research was being done on that.)
You don't have droughts, floods, or pests* to deal with, and even pollenation might be handled through automated systems, such that every flower gets pollenated and the maximum yield is given.
* If you have nano-technology, you do not need even most of the "beneficial" life forms in earth-bound ecosystems. Your programmable nano-machines do the pollenation, and as much as possible, they also even do the recycling of materials.
** on the other hand, you would still want to bring along enough revivable DNA to produce a permanent, stable ecosystem "somewhere"....
*** this is certainly a stretch, but it may be possible for nano-machines to mass produce synthetic foods which are indistinguishable from "natural" crops. While this appears too "trekky" it should theoretically be possible in many cases. Moore's law suggests this may actually be one of the EASIER solutions to any of ht eproblems related to space flight, because computers should be small enough and powerful enough to allow Borg style nano-scale robots within about 30-40 years. This would allow controlled manufacturing of food on a molecule by molecule basis, with an absolute minimum of waste.
With existing methods, crops to support 880 people equates to about 2km worth of floor space. But with the greenhouse concept, you could also have "hanging gardens" maximizing the efficiency of each given portion of floor space, which is not terribly significant for many crops, but worth mentioning for some.
still, floor space is a serious problem because 2km is already more than the largest existing sky scrapers...
Saturn might object.
Arthur
But there just aren't that many stars that close to us that are likely to fill the pre-req.
In fact there are only 6 yellow suns within 20 LYs of Earth, but 2 of those are binary stars and so are not suitable.
http://www.atlasoftheuniverse.com/20lys.html
Since I think it HIGHLY unlikely that we would ever manage a mission with an average speed greater than 0.1 c, and since it's not likely the planet you are looking for is closer than 20 LYs, so the shortest this mission is likely to be is a 200+ year mission.
At which point I think it's reasonable to ask, what's the point?
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
QUOTE (uaafanblog+)
I'm of the opinion that there's a good reason that we humans have a genetic predisposition to push frontier boundaries. It has served us well to this point in our history and I fully believe it will serve us well in the future. There are clearly no candidates to fill that need in our system ... so we're going to have to figure out a way to make it happen in the future. Perhaps that means slow moving generational ships as a follow-on to the probe mission.
Ok, so now its roughly 250 years after the probe that found a suitable planet was launched. I still find it quite unlikely that you could recruit enough qualified people who would be willing to commit themselves and the next 5 generations of their progeny to a life limited to a spaceship.
Worse, even if you did, and vetted the adults, how could you predict how the 2nd through 4th generations would take this? You know, the ones destined to die in space without ever leaving the confines of the prison their great great grandparents chose for them?
If I was in charge when the 2nd generation took over, I'm pretty sure I'd turn the craft around and say 'screw this', at least my grand kids get to grow up on a planet, not die in transit to a star we wouldn't even be sure we could live on.
Since you've selected what appears to be a perfect planet for life, then if the probe found life, would this be a GOOD thing, or a BAD thing, and how would you tell?
The other huge question about a generational ship is how many people are needed?
See: http://www.physforum.com/index.php?showtop...ndpost&p=435459
And in a generational ship, you have to allow for the elderly and the young (the elderly have to primarily teach and the young have an incredible amount to learn).
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and the food and water (and plants and animals?) and tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
Then go back and figure out what that means in terms of fuel, because, even at 100% efficiency, with an engine that converted mass directly to energy, you would need approximately 800 kgs of fuel for every kg of vessel making a 25 LY voyage.
Final note, the generational arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have been started by Ferdinand and Isabella.
Arthur
Ok, so now its roughly 250 years after the probe that found a suitable planet was launched. I still find it quite unlikely that you could recruit enough qualified people who would be willing to commit themselves and the next 5 generations of their progeny to a life limited to a spaceship.
Worse, even if you did, and vetted the adults, how could you predict how the 2nd through 4th generations would take this? You know, the ones destined to die in space without ever leaving the confines of the prison their great great grandparents chose for them?
If I was in charge when the 2nd generation took over, I'm pretty sure I'd turn the craft around and say 'screw this', at least my grand kids get to grow up on a planet, not die in transit to a star we wouldn't even be sure we could live on.
Since you've selected what appears to be a perfect planet for life, then if the probe found life, would this be a GOOD thing, or a BAD thing, and how would you tell?
The other huge question about a generational ship is how many people are needed?
See: http://www.physforum.com/index.php?showtop...ndpost&p=435459
And in a generational ship, you have to allow for the elderly and the young (the elderly have to primarily teach and the young have an incredible amount to learn).
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and the food and water (and plants and animals?) and tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
Then go back and figure out what that means in terms of fuel, because, even at 100% efficiency, with an engine that converted mass directly to energy, you would need approximately 800 kgs of fuel for every kg of vessel making a 25 LY voyage.
Final note, the generational arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have been started by Ferdinand and Isabella.
Arthur
Ok as promised, the Kepler mission's first discoveries were announced today.
Here's a link to the release which I'll endeavor to summarize below from both the release and what I already know about the program as I've been following it.
5 new planets have been confirmed and hundreds of other signatures have been registered which are all in the process of being confirmed. Confirmations come from a combination of additional transit signatures and ground-based observations from existing exoplanet studies.
All 5 are of "hot Jupiter" variety (no orbit greater than 5 days in this group) and were contained within the first 6 weeks worth of data. Kepler downloads somewhere in the neighborhood of 100 gigabytes of data once a month. Additional updates during this weeks AAS convention in D.C. may be forthcoming. According to an additional source (which I've unfortunately lost), several papers are expected to be announced there.
This announcement is in-line with what they "expected". It perhaps might seem underwhelming to someone skeptical but it's early days. Any "earth-analogue" discovery shouldn't be expected prior to 2012.
This missions management seems to be adhering to a strictly conservative approach with regard to announcements. NASA has been known to overstate a thing or two and my personal interpretation with regard to this mission manager is that he's not saying anything about anything without solid confirmation.
Here's a link to the release which I'll endeavor to summarize below from both the release and what I already know about the program as I've been following it.
5 new planets have been confirmed and hundreds of other signatures have been registered which are all in the process of being confirmed. Confirmations come from a combination of additional transit signatures and ground-based observations from existing exoplanet studies.
All 5 are of "hot Jupiter" variety (no orbit greater than 5 days in this group) and were contained within the first 6 weeks worth of data. Kepler downloads somewhere in the neighborhood of 100 gigabytes of data once a month. Additional updates during this weeks AAS convention in D.C. may be forthcoming. According to an additional source (which I've unfortunately lost), several papers are expected to be announced there.
This announcement is in-line with what they "expected". It perhaps might seem underwhelming to someone skeptical but it's early days. Any "earth-analogue" discovery shouldn't be expected prior to 2012.
This missions management seems to be adhering to a strictly conservative approach with regard to announcements. NASA has been known to overstate a thing or two and my personal interpretation with regard to this mission manager is that he's not saying anything about anything without solid confirmation.
Well thanks for that update.
Of course it certainly doesn't rise to the promised level of "beyond anything NASA had expected or could have predicted" but then they are apparently way behind in the data analysis as these results are supposedly from only the first 6 weeks of data.
So at this rate, a bit over a month to analyze a week of data, it could take several years to get decent results.
Guess if you are in the exoplanet hunt you just gotta be patient.
Arthur
Of course it certainly doesn't rise to the promised level of "beyond anything NASA had expected or could have predicted" but then they are apparently way behind in the data analysis as these results are supposedly from only the first 6 weeks of data.
So at this rate, a bit over a month to analyze a week of data, it could take several years to get decent results.
Guess if you are in the exoplanet hunt you just gotta be patient.
Arthur
QUOTE (adoucette+Jan 5 2010, 03:16 PM)
Of course it certainly doesn't rise to the promised level of "beyond anything NASA had expected or could have predicted" but then they are apparently way behind in the data analysis as these results are supposedly from only the first 6 weeks of data.
Yeah, I was a little let down too, but maybe the fantastic stuff is on its way.
Yeah, I was a little let down too, but maybe the fantastic stuff is on its way.
QUOTE (uaafanblog+Apr 21 2009, 11:33 AM)
So far there are two systems with rocky planets that we know of ... ours and Gilese 581 ... our solar system has 3 planets that we might detect as being in the habitable zone and Gilese has 2 it seems (the first candidates yet from from ground based observation)..
Here is a link to the astronomy and astrophysics article.
Interestingly Gilese is an M dwarf star with about one third the radius of our sun. The warm end of the habitable zone is a planet with a 12 day orbit and the cold end of the habitable zone is a planet with a 66 day orbit. The inner one is 5 earth masses and the outer is 7.7 earth masses.
I finally read that article and I don't see where it claims any of these planets are rocky.
Seems to me they are all much larger, but low mass planets.
Am I missing something?
Arthur
Here is a link to the astronomy and astrophysics article.
Interestingly Gilese is an M dwarf star with about one third the radius of our sun. The warm end of the habitable zone is a planet with a 12 day orbit and the cold end of the habitable zone is a planet with a 66 day orbit. The inner one is 5 earth masses and the outer is 7.7 earth masses.
I finally read that article and I don't see where it claims any of these planets are rocky.
Seems to me they are all much larger, but low mass planets.
QUOTE
Recent planet-formation simulations (Laughlin et al. 2004; Ida & Lin 2005) suggest that planet formation around low-mass primaries tends to produce lower-mass planets, in the Uranus/Neptune domain. Formation of lower-mass planets is also favoured for solar-mass stars with metal-poor protostellar nebulae (Ida & Lin 2004; Benz et al. 2006). Gl 581 is a 0.3 metal-poor star, and these detected very light planets are thus just what was expected around this star. Additional detections of very low-mass planets will help in understanding these 2 converging effects.
Am I missing something?
Arthur
QUOTE (adoucette+Jan 5 2010, 12:55 PM)
I finally read that article and I don't see where it claims any of these planets are rocky.
Seems to me they are all much larger, but low mass planets.
Am I missing something?
Arthur
Unfortunately, I only linked to one source back when I posted that. The rocky designations had come from somewhere else .. most likely speculation in more populist science media (I generally look at multiple articles and just link to the most authoritative --- when I'm smart enough to link).
A quick recapitulation of sourcing tells me that 581c is "believed to be rocky by some" and there is no certain such designation for the other 581d.
So I'd say that my original statement was instead an over-statement with regard to "rockiness".
And apparently these aren't Kepler candidates (I'm not sure if they're even in the view field) because their transits can't be viewed from Earth.
Seems to me they are all much larger, but low mass planets.
Am I missing something?
Arthur
Unfortunately, I only linked to one source back when I posted that. The rocky designations had come from somewhere else .. most likely speculation in more populist science media (I generally look at multiple articles and just link to the most authoritative --- when I'm smart enough to link).
A quick recapitulation of sourcing tells me that 581c is "believed to be rocky by some" and there is no certain such designation for the other 581d.
So I'd say that my original statement was instead an over-statement with regard to "rockiness".
And apparently these aren't Kepler candidates (I'm not sure if they're even in the view field) because their transits can't be viewed from Earth.
QUOTE (uaafanblog+Jan 6 2010, 02:54 AM)
Unfortunately, I only linked to one source back when I posted that. The rocky designations had come from somewhere else .. most likely speculation in more populist science media (I generally look at multiple articles and just link to the most authoritative --- when I'm smart enough to link).
A quick recapitulation of sourcing tells me that 581c is "believed to be rocky by some" and there is no certain such designation for the other 581d.
So I'd say that my original statement was instead an over-statement with regard to "rockiness".
And apparently these aren't Kepler candidates (I'm not sure if they're even in the view field) because their transits can't be viewed from Earth.
If I recall correctly, one of those Gliese planets has a density of about 2.3 grams per cm^3, so it is thought to be an ocean world.
A quick recapitulation of sourcing tells me that 581c is "believed to be rocky by some" and there is no certain such designation for the other 581d.
So I'd say that my original statement was instead an over-statement with regard to "rockiness".
And apparently these aren't Kepler candidates (I'm not sure if they're even in the view field) because their transits can't be viewed from Earth.
If I recall correctly, one of those Gliese planets has a density of about 2.3 grams per cm^3, so it is thought to be an ocean world.
QUOTE (gocrew+Jan 5 2010, 06:03 PM)
If I recall correctly, one of those Gliese planets has a density of about 2.3 grams per cm^3, so it is thought to be an ocean world.
It's unfortunate that so many exoplanet scientists allow their speculation about unknown aspects of these discoveries to end up in the press as demi-facts. Journalists certainly seem to encourage these folks to speculate but once they do the articles rarely reflect how these inferences emerge.
In the Gliese cases, I've also read that "c" may be a Venus-type runaway greenhouse planet. And that came from inferred temperature estimates. What we all have to remember in the case of the Gliese discoveries is that there has been no direct observation and that all this speculation comes from nothing other than the gravitational pertubations of the host star from the planets.
Mass can certainly be gauged with some reasonable expectation of accuracy however, I don't see much basis for volume estimations. There are some leaps of inference that may or may not be true.
Hopefully, within a timeframe of about 20 years or less we'll begin to image some of the exoplanets that we've already discovered along with whatever future ones that Kepler identifies. ESA has a telescope planned called Gaia that may advance that and NASA's next generation interferometer (whichever proposal ultimately gets funded) will be another step forward.
I read about some boobs that funded a high power radio transmission to Gliese. I'm all about finding any sort of exobiology but to extrapolate some minor possibility and actually spend money to fund such a thing seems like a waste of personal resources. Thank goodness it was funded with private money.
It's unfortunate that so many exoplanet scientists allow their speculation about unknown aspects of these discoveries to end up in the press as demi-facts. Journalists certainly seem to encourage these folks to speculate but once they do the articles rarely reflect how these inferences emerge.
In the Gliese cases, I've also read that "c" may be a Venus-type runaway greenhouse planet. And that came from inferred temperature estimates. What we all have to remember in the case of the Gliese discoveries is that there has been no direct observation and that all this speculation comes from nothing other than the gravitational pertubations of the host star from the planets.
Mass can certainly be gauged with some reasonable expectation of accuracy however, I don't see much basis for volume estimations. There are some leaps of inference that may or may not be true.
Hopefully, within a timeframe of about 20 years or less we'll begin to image some of the exoplanets that we've already discovered along with whatever future ones that Kepler identifies. ESA has a telescope planned called Gaia that may advance that and NASA's next generation interferometer (whichever proposal ultimately gets funded) will be another step forward.
I read about some boobs that funded a high power radio transmission to Gliese. I'm all about finding any sort of exobiology but to extrapolate some minor possibility and actually spend money to fund such a thing seems like a waste of personal resources. Thank goodness it was funded with private money.
Well, I've looked at these things before, and even seen several documentaries on the known exo-planets on discovery channel, etc, but they tend to be highly speculative, and can sometimes even be quite comical in their speculations.
Like, how far is the closest known exo-planet that is relatively close to earth mass? If I remember right, "Something" was found within a few dozen light years, but I'm not sure which planet it was.
As far as I know, almost everything that has been discovered so far was classified as a "hot jupiter" which makes it useless for human purposes. In most cases, they have even more severe temperatures than venus, and wouldn't even be possible to explore with an un-manned probe...
Like, how far is the closest known exo-planet that is relatively close to earth mass? If I remember right, "Something" was found within a few dozen light years, but I'm not sure which planet it was.
As far as I know, almost everything that has been discovered so far was classified as a "hot jupiter" which makes it useless for human purposes. In most cases, they have even more severe temperatures than venus, and wouldn't even be possible to explore with an un-manned probe...
Odd results...
http://exoplanet.eu/star.php?st=GJ+1214
That "radius" is probably given an estimate of the radius at the top of the atmosphere.
This isn't terribly large planet, as I calculate that equates to 5.67 earth masses, and 2.7 earth radius(19.7 earth volumes).
This gives the surface gravity at about 0.7744 g, however, this "surface" is just the top of the atmosphere, if it has one, and is not necessarily the rocky or liquid surface.
Still, this number for "surface gravity" should be "safe", for speculation purposes, as it is also actually less than the earth's gravity at the top of its atmosphere, which is about 0.88g.
Which suggests that most of this planet's "size" is coming from a very large atmosphere, very deep oceans, OR relatively light rock; MUCH lighter than the rock of earth, on average.
The overal density of the planet is significantly less than earth.
At earth's average density, a planet of 2.7 earth radius would be expected to have about 19-20 earth masses. Therefore, this planet is only about 1/4th the average density of earth.
This is still much more dense than Saturn, but possibly a water world with rocky core, or small gas giant (~half the mass of neptune) with rocky core.
These numbers obviously must be taken with a grain of salt as it is so several light years away and the real margins of error may be outside the claimed margin of error.
http://exoplanet.eu/star.php?st=GJ+1214
That "radius" is probably given an estimate of the radius at the top of the atmosphere.
This isn't terribly large planet, as I calculate that equates to 5.67 earth masses, and 2.7 earth radius(19.7 earth volumes).
This gives the surface gravity at about 0.7744 g, however, this "surface" is just the top of the atmosphere, if it has one, and is not necessarily the rocky or liquid surface.
Still, this number for "surface gravity" should be "safe", for speculation purposes, as it is also actually less than the earth's gravity at the top of its atmosphere, which is about 0.88g.
Which suggests that most of this planet's "size" is coming from a very large atmosphere, very deep oceans, OR relatively light rock; MUCH lighter than the rock of earth, on average.
The overal density of the planet is significantly less than earth.
At earth's average density, a planet of 2.7 earth radius would be expected to have about 19-20 earth masses. Therefore, this planet is only about 1/4th the average density of earth.
This is still much more dense than Saturn, but possibly a water world with rocky core, or small gas giant (~half the mass of neptune) with rocky core.
These numbers obviously must be taken with a grain of salt as it is so several light years away and the real margins of error may be outside the claimed margin of error.
Of course, the orbital period of about 1.6 days would have it being roasted like a marshmallow non-stop, and any liquid oceans definitely aren't made of water...at that distance from the star, it may be entirely vaporized...even the metals...
http://exoplanet.eu/planet.php?p1=Kepler-4&p2=b
Kepler 4b
~24.47 earth masses
~4 earth radius.
Density, ~0.38 of earth density.
Conjecture:
Gas Giant
uninhabitable, unexplorable, un-probable
====
Kepler 5b
Really is a "hot Jupiter" by any definition.
uninhabitable, unexplorable, un-probable
====
Kepler 6b
hot jupiter
uninhabitable, unexplorable, un-probable
====
Kepler 7b
hot jupiter
uninhabitable, unexplorable, un-probable
====
Kepler 8b
hot jupiter
uninhabitable, unexplorable, un-probable
These are all so close to their respective stars that even a probe would burn up, possibly before ever reaching the planet, much less entering atmosphere.
Kepler 4b
~24.47 earth masses
~4 earth radius.
Density, ~0.38 of earth density.
Conjecture:
Gas Giant
uninhabitable, unexplorable, un-probable
====
Kepler 5b
Really is a "hot Jupiter" by any definition.
uninhabitable, unexplorable, un-probable
====
Kepler 6b
hot jupiter
uninhabitable, unexplorable, un-probable
====
Kepler 7b
hot jupiter
uninhabitable, unexplorable, un-probable
====
Kepler 8b
hot jupiter
uninhabitable, unexplorable, un-probable
These are all so close to their respective stars that even a probe would burn up, possibly before ever reaching the planet, much less entering atmosphere.
QUOTE (adoucette+Dec 31 2009, 09:58 AM)
QUOTE
The other huge question about a generational ship is how many people are needed?
Several dozen to less than 100 unique individuals, perferably inter-racial couples as they would have solved the "race" problem.
QUOTE (->
| QUOTE |
| The other huge question about a generational ship is how many people are needed? |
Several dozen to less than 100 unique individuals, perferably inter-racial couples as they would have solved the "race" problem.
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and the food and water (and plants and animals?) and tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
You assume they need to land right away. This isn't necessarily the case. They may be able to construct a landing vehicle or additional self-sustained Dyson Structures from asteroids and small moons in the vacinity, before ever landing on the target planet.
QUOTE
Then go back and figure out what that means in terms of fuel, because, even at 100% efficiency, with an engine that converted mass directly to energy, you would need approximately 800 kgs of fuel for every kg of vessel making a 25 LY voyage.
This is definitely wrong numbers. You are likely making some sort of mistake like I did the first several times I tried to understand anti-matter and nuclear propulsion.
A FIVE PERCENT efficient anti-matter drive requires far less fuel mass than the ship's mass, and has a maximum velocity of at least 0.8c.
You can get this from E=2MC^2 (where "M" is the mass of anti-matter, and is doubled by the mass of the matter component of fuel) and then calculate to convert this to momentum of the ship, then factor velocity.
0.5kg matter + 0.5kg anti-matter yields:
1kg*c^2 = 9*10^16 kg*m^2/s^2
Which if you do the math, should put the space shuttle insanely close to light speed, even with relativistic effects. like 0.999999c...
Less than half a Kilogram of antimatter is enough to accelerate the space shuttle to very near light speed, to within maximum theoretical limits of antimatter drives, which are commonly reported as at least 0.8c. Though honestly, I think the number is arbitrarily close to c, because nobody has ever given a reason why 0.8c should be a limit if you are carrying larger amount of anti-matter, since acceleration and velocity are themselves relative.
A FIFTY PERCENT efficient fusion drive would require about as much fuel mass as the ship's mass (to within reasonable scale factors relative to the engine's minimum or maximum safe size). This is to obtain the maximum theoretical velocity of a fusion ship.
QUOTE (->
| QUOTE |
| Then go back and figure out what that means in terms of fuel, because, even at 100% efficiency, with an engine that converted mass directly to energy, you would need approximately 800 kgs of fuel for every kg of vessel making a 25 LY voyage. |
This is definitely wrong numbers. You are likely making some sort of mistake like I did the first several times I tried to understand anti-matter and nuclear propulsion.
A FIVE PERCENT efficient anti-matter drive requires far less fuel mass than the ship's mass, and has a maximum velocity of at least 0.8c.
You can get this from E=2MC^2 (where "M" is the mass of anti-matter, and is doubled by the mass of the matter component of fuel) and then calculate to convert this to momentum of the ship, then factor velocity.
0.5kg matter + 0.5kg anti-matter yields:
1kg*c^2 = 9*10^16 kg*m^2/s^2
Which if you do the math, should put the space shuttle insanely close to light speed, even with relativistic effects. like 0.999999c...
Less than half a Kilogram of antimatter is enough to accelerate the space shuttle to very near light speed, to within maximum theoretical limits of antimatter drives, which are commonly reported as at least 0.8c. Though honestly, I think the number is arbitrarily close to c, because nobody has ever given a reason why 0.8c should be a limit if you are carrying larger amount of anti-matter, since acceleration and velocity are themselves relative.
A FIFTY PERCENT efficient fusion drive would require about as much fuel mass as the ship's mass (to within reasonable scale factors relative to the engine's minimum or maximum safe size). This is to obtain the maximum theoretical velocity of a fusion ship.
Final note, the generational arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have been started by Ferdinand and Isabella.
Why everyone in modern times considers generational projects as "impossible" or "pointless" is beyond me.
In ancient times people constructed generational projects in nearly every major civilization, in many cases having no real function in terms of resources.
We construct "useless" semi-generational structures all the time and don't even think about it. We call them "Sports Arenas" and while they technically "pay" for themselves in dollars, at least to the owner, they have no "real" economic value, because they do not produce goods or energy.
QUOTE (Quantum_Conundrum+Jan 17 2010, 10:39 PM)
This is definitely wrong numbers. You are likely making some sort of mistake like I did the first several times I tried to understand anti-matter and nuclear propulsion.
QUOTE (adoucette+Jan 17 2010, 11:26 PM)
Don't think so.
See http://math.ucr.edu/home/baez/physics/Rela.../SR/rocket.html
Arthur
See, I looked at that website last night and studied that for over an hour, because its about what I had ORIGINALLY came up with by hand using a graphical approach.
However, I always felt that "something" was wrong with my original numbers.
However, when I even use the formula on that website, I got that 2kg of antimatter is enough to make 1kg go 0.8c.
But these numbers DON'T make sense, even considering relativity.
E=MC^2 = 9x10^16 kgm^2/s^2
If you actually look at the formula, a Kilogram of annihilated matter and anti-matter "should" accelerate a kilogram of matter EXACTLY to the speed of light in an ideal machine.
Moreover, the numbers on that website, and the numbers I originally got about 2 years ago, are simply ludicrously large. NOBODY would even bother discussing an antimatter drive at all if they really are right, but some pretty big names do it all the time, especially on Discovery channel, and usually seem to indicate that a few kilograms of anti-matter is enough to make a starship.
If the numbers on that website are correct, there simply will never be a man made starship and there are no such thing as type 3 civilizations, because the energy requirements are simply beyond the possibility of anybody on a single solar system to create enough antimatter to make a starship. You really would need a REAL dyson sphere to ever produce enough energy to create that much anti-matter at any remotefly feasible efficiency, and since everyone on this forum seems to agree that isn't possible either.....
He says 10 kg fuel per kg payload to go to nearest star in an allegedly ideal machine.
So to send the 24,400kg payload of the Space Shuttle to the nearest star on a one-way no-stopping trip, according to his calculations, would take 122,000kg of anti-matter anihilated with 122,000kg of matter.
or 244,000 Tzar Bombas worth of energy.
This doesn't really make sense at all, because the Orion project is thought to be capable of 0.1c using only a few hundred to a few thousand small -medium Fission Bombs.
A calculation done by graphics calculator shows that 0.8c should take only about 13 times more power than 0.1c, because the Lorentz Factor is only 1.6666..., not some huge number like 10 or 100 or 100,000....
http://www.youtube.com/watch?v=9Llt4GhGnRk
And if NASA thinks it's possibly going to be sending nano-probes to another star sometime relatively soon, what the hell is the fuel source, if the numbers from that page are right? These "nano probes" would still need to be on an anti-matter rocket that cost quadrilions to make in order to make a one way, no-stopping trip in a reasonable amount of time...
If they sent the probes on conventional rocketry, or some sort of nano-ion rocket, even still, there would be nobody here alive using existing technologies, and barring ridiculous backwards compatibility indefinitely, nobody would even remember the mission ever happened, and nobody would be waiting for a signal at all...and in the case of all but the closest stars, the power source would fail long before then anyway, even if it were a radio-isotope power supply. Even un-manned missions are completely IMPOSSIBLE at anything less than 0.1c.
I think the numbers on that site MUST be wrong somehow, because our good DOCTOR is smarter than that. Even He wouldn't be going around talking like this is a century away if those numbers are right. It would take eons to make even an interstellar nano-probe.
See http://math.ucr.edu/home/baez/physics/Rela.../SR/rocket.html
Arthur
See, I looked at that website last night and studied that for over an hour, because its about what I had ORIGINALLY came up with by hand using a graphical approach.
However, I always felt that "something" was wrong with my original numbers.
However, when I even use the formula on that website, I got that 2kg of antimatter is enough to make 1kg go 0.8c.
But these numbers DON'T make sense, even considering relativity.
E=MC^2 = 9x10^16 kgm^2/s^2
If you actually look at the formula, a Kilogram of annihilated matter and anti-matter "should" accelerate a kilogram of matter EXACTLY to the speed of light in an ideal machine.
Moreover, the numbers on that website, and the numbers I originally got about 2 years ago, are simply ludicrously large. NOBODY would even bother discussing an antimatter drive at all if they really are right, but some pretty big names do it all the time, especially on Discovery channel, and usually seem to indicate that a few kilograms of anti-matter is enough to make a starship.
If the numbers on that website are correct, there simply will never be a man made starship and there are no such thing as type 3 civilizations, because the energy requirements are simply beyond the possibility of anybody on a single solar system to create enough antimatter to make a starship. You really would need a REAL dyson sphere to ever produce enough energy to create that much anti-matter at any remotefly feasible efficiency, and since everyone on this forum seems to agree that isn't possible either.....
He says 10 kg fuel per kg payload to go to nearest star in an allegedly ideal machine.
So to send the 24,400kg payload of the Space Shuttle to the nearest star on a one-way no-stopping trip, according to his calculations, would take 122,000kg of anti-matter anihilated with 122,000kg of matter.
or 244,000 Tzar Bombas worth of energy.
This doesn't really make sense at all, because the Orion project is thought to be capable of 0.1c using only a few hundred to a few thousand small -medium Fission Bombs.
A calculation done by graphics calculator shows that 0.8c should take only about 13 times more power than 0.1c, because the Lorentz Factor is only 1.6666..., not some huge number like 10 or 100 or 100,000....
http://www.youtube.com/watch?v=9Llt4GhGnRk
And if NASA thinks it's possibly going to be sending nano-probes to another star sometime relatively soon, what the hell is the fuel source, if the numbers from that page are right? These "nano probes" would still need to be on an anti-matter rocket that cost quadrilions to make in order to make a one way, no-stopping trip in a reasonable amount of time...
If they sent the probes on conventional rocketry, or some sort of nano-ion rocket, even still, there would be nobody here alive using existing technologies, and barring ridiculous backwards compatibility indefinitely, nobody would even remember the mission ever happened, and nobody would be waiting for a signal at all...and in the case of all but the closest stars, the power source would fail long before then anyway, even if it were a radio-isotope power supply. Even un-manned missions are completely IMPOSSIBLE at anything less than 0.1c.
I think the numbers on that site MUST be wrong somehow, because our good DOCTOR is smarter than that. Even He wouldn't be going around talking like this is a century away if those numbers are right. It would take eons to make even an interstellar nano-probe.
Take it up with Dr Koks
The articles in this FAQ are based on those discussions and on information from good reference sources. That does not mean that they are always perfect and complete. If you have corrections, updates or additional points to make please send an email to the editor, Don Koks dkoks@physics.adelaide.edu.au
His CV
Koks holds a doctorate from the Department of Physics and Mathematical Physics at Adelaide University, with a thesis in mathematical physics completed in 1996.
His PhD work was concerned with quantum statistical methods, wherein he used the tool of influence functionals to look at decoherence and entropy in the early universe, as well as related topics such as thermal radiance of black holes.
Completed a masters degree in physics with first class honours in the Physics Department at the University of Auckland in 1991, specialising in applied accelerator physics.
He was also awarded Senior Prizes in Physics (1988) and Mathematics (1987).
Arthur
The articles in this FAQ are based on those discussions and on information from good reference sources. That does not mean that they are always perfect and complete. If you have corrections, updates or additional points to make please send an email to the editor, Don Koks dkoks@physics.adelaide.edu.au
His CV
Koks holds a doctorate from the Department of Physics and Mathematical Physics at Adelaide University, with a thesis in mathematical physics completed in 1996.
His PhD work was concerned with quantum statistical methods, wherein he used the tool of influence functionals to look at decoherence and entropy in the early universe, as well as related topics such as thermal radiance of black holes.
Completed a masters degree in physics with first class honours in the Physics Department at the University of Auckland in 1991, specialising in applied accelerator physics.
He was also awarded Senior Prizes in Physics (1988) and Mathematics (1987).
Arthur
QUOTE (adoucette+Jan 18 2010, 10:18 AM)
Take it up with Dr Koks
The articles in this FAQ are based on those discussions and on information from good reference sources. That does not mean that they are always perfect and complete. If you have corrections, updates or additional points to make please send an email to the editor, Don Koks dkoks@physics.adelaide.edu.au
His CV
Koks holds a doctorate from the Department of Physics and Mathematical Physics at Adelaide University, with a thesis in mathematical physics completed in 1996.
His PhD work was concerned with quantum statistical methods, wherein he used the tool of influence functionals to look at decoherence and entropy in the early universe, as well as related topics such as thermal radiance of black holes.
Completed a masters degree in physics with first class honours in the Physics Department at the University of Auckland in 1991, specialising in applied accelerator physics.
He was also awarded Senior Prizes in Physics (1988) and Mathematics (1987).
Arthur
So why is he standing there telling everyone this might be possible in 100 years?
Some rough numbers I did to find out how much hydrogen is needed to fuse to make enough anti-matter to make a one way no-stop acceleration to 0.8c, came up with this.
24.4 million kilograms of hydrogen must be fused to produce enough anti-matter at 50% total energy efficiency to accelerate a space shuttle's payload to 0.8c with a 100% efficient anti-matter engine.
This would take eons and eons to make a "real" 3-7 manned anti-matter space-craft according to those numbers, and this doesn't even consider the exponential increase in needed anti-matter to be able to stop at the other end.
With those numbers, an actual 0.8c, hundred person colony ship would require fusing most, if not all, of the hydrogen on the entire planet, and possibly much of the hydrogen on other planets and moons in the solar system.
With those numbers, anything above about 0.2c ends up being so ridiculously inefficient and expensive that there would never, ever, be any practical reason to do so, regardless of technology level, not even for colonization.
I mean, you could make scores of round trips at 0.1c or 0.2c for the same cost as a one way, no stop trip at 0.8c, whch is ludicrous, so why bother?
You certainly wouldn't have intergalactic highways at all. You would only have one-way stop and go colony ships, and perhaps interstellar communication relays as I have previously discussed, this even with the best remotely concievable anti-matter engine.
The articles in this FAQ are based on those discussions and on information from good reference sources. That does not mean that they are always perfect and complete. If you have corrections, updates or additional points to make please send an email to the editor, Don Koks dkoks@physics.adelaide.edu.au
His CV
Koks holds a doctorate from the Department of Physics and Mathematical Physics at Adelaide University, with a thesis in mathematical physics completed in 1996.
His PhD work was concerned with quantum statistical methods, wherein he used the tool of influence functionals to look at decoherence and entropy in the early universe, as well as related topics such as thermal radiance of black holes.
Completed a masters degree in physics with first class honours in the Physics Department at the University of Auckland in 1991, specialising in applied accelerator physics.
He was also awarded Senior Prizes in Physics (1988) and Mathematics (1987).
Arthur
So why is he standing there telling everyone this might be possible in 100 years?
Some rough numbers I did to find out how much hydrogen is needed to fuse to make enough anti-matter to make a one way no-stop acceleration to 0.8c, came up with this.
24.4 million kilograms of hydrogen must be fused to produce enough anti-matter at 50% total energy efficiency to accelerate a space shuttle's payload to 0.8c with a 100% efficient anti-matter engine.
This would take eons and eons to make a "real" 3-7 manned anti-matter space-craft according to those numbers, and this doesn't even consider the exponential increase in needed anti-matter to be able to stop at the other end.
With those numbers, an actual 0.8c, hundred person colony ship would require fusing most, if not all, of the hydrogen on the entire planet, and possibly much of the hydrogen on other planets and moons in the solar system.
With those numbers, anything above about 0.2c ends up being so ridiculously inefficient and expensive that there would never, ever, be any practical reason to do so, regardless of technology level, not even for colonization.
I mean, you could make scores of round trips at 0.1c or 0.2c for the same cost as a one way, no stop trip at 0.8c, whch is ludicrous, so why bother?
You certainly wouldn't have intergalactic highways at all. You would only have one-way stop and go colony ships, and perhaps interstellar communication relays as I have previously discussed, this even with the best remotely concievable anti-matter engine.
No one ever said interstellar travel was quick or easy.
Well, except you.
Oh, and I don't see where Dr Koks claims it might be possible in 100 years.
Arthur
Well, except you.
Oh, and I don't see where Dr Koks claims it might be possible in 100 years.
Arthur
Entropy and the life time of the power source for the environment are the only real reasons to go faster.
There must be an optimum total efficiency curve based on the minimum mass of a ship supporting N persons, and the minimum mass of the life support system's power supply vs the energy cost of the engine.
That is, the faster you go, the less life support you need, but the cost of propulsion increases exponentially, so there must be an optimum non-zero velocity for the least total energy cost.
Total cost = propulsion + payload
Payload cost is a function of the lifesupport needs and all supporting technologies and all technologies expected to be needed upon arival (though even this function is so vast we don't know exactly what it looks like yet.)
So then, at what non-zero velocity is total cost least?
Are there even anyone, other than people on this forum, who has tried to make ballpark estmates and graphs of this relationship for relativistic velocities and interstellar travel?
Specificly, the cost of the engine vs the cost of the life support's power supply for any given value of v from 0 to 0.99c?
The power supply is the sum of the amount of energy needed to run all gadgets for the entire trip, and support the entire biosphere for the entire trip. (Even life energy must ultimately come from the annihilation of anti-matter or else a fusion reactor.)
There must be an optimum total efficiency curve based on the minimum mass of a ship supporting N persons, and the minimum mass of the life support system's power supply vs the energy cost of the engine.
That is, the faster you go, the less life support you need, but the cost of propulsion increases exponentially, so there must be an optimum non-zero velocity for the least total energy cost.
Total cost = propulsion + payload
Payload cost is a function of the lifesupport needs and all supporting technologies and all technologies expected to be needed upon arival (though even this function is so vast we don't know exactly what it looks like yet.)
So then, at what non-zero velocity is total cost least?
Are there even anyone, other than people on this forum, who has tried to make ballpark estmates and graphs of this relationship for relativistic velocities and interstellar travel?
Specificly, the cost of the engine vs the cost of the life support's power supply for any given value of v from 0 to 0.99c?
The power supply is the sum of the amount of energy needed to run all gadgets for the entire trip, and support the entire biosphere for the entire trip. (Even life energy must ultimately come from the annihilation of anti-matter or else a fusion reactor.)
It doesn't matter.
No one you know is ever going to go on an interstellar voyage.
There are only 6 yellow suns within 20 LYs of Earth, but 2 of those are binary stars and so are not suitable.
http://www.atlasoftheuniverse.com/20lys.html
Since I think it HIGHLY unlikely that we would ever manage a mission with an average speed greater than 0.1 c, and since it's not likely the planet you are looking for is closer than 20 LYs, so the shortest this mission is likely to be is a 200+ year mission.
At which point I think it's reasonable to ask, what's the point?
You aren't going to go off on a 200+ year mission without knowing your destination are you?
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
Ok, so now were lucky and its roughly 250 to 300 years after the probe that found a suitable planet was launched and we try to recruit enough qualified people who would be willing to commit themselves and the next 5 generations of their progeny to a life limited to a spaceship.
Good luck finding SUITABLE candidates for that.
Worse, even if you did, and vetted the adults, how could you predict how the 2nd through 4th generations would take this? You know, the ones destined to die in space without ever leaving the confines of the prison their great great grandparents chose for them?
If I was in charge when the 2nd generation took over, I'm pretty sure I'd turn the craft around and say 'screw this', at least my grand kids get to grow up on a planet, not die in transit to a star we wouldn't even be sure we could live on.
The other huge question about a generational ship is how many people are needed?
See: http://www.physforum.com/index.php?showtop...ndpost&p=435459
And no, providing for just 100 people is WAY too small a number for a 200+ year voyage. You don't necessarily have to start with all you need to complete the jouney, but the number will be quite a bit bigger than 100.
In a generational ship, you have to allow for the elderly and the young (the elderly have to primarily teach and the young have an incredible amount to learn).
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and grow the food and recycle the O2 and the water and waste and provide the energy (can't use solar energy) and be able to repair any part of the ship and make the tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
Oh, and the generational craft's arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have to have been started by Ferdinand and Isabella.
And NO, that's not the same as building a sport arena.
Arthur
No one you know is ever going to go on an interstellar voyage.
There are only 6 yellow suns within 20 LYs of Earth, but 2 of those are binary stars and so are not suitable.
http://www.atlasoftheuniverse.com/20lys.html
Since I think it HIGHLY unlikely that we would ever manage a mission with an average speed greater than 0.1 c, and since it's not likely the planet you are looking for is closer than 20 LYs, so the shortest this mission is likely to be is a 200+ year mission.
At which point I think it's reasonable to ask, what's the point?
You aren't going to go off on a 200+ year mission without knowing your destination are you?
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
Ok, so now were lucky and its roughly 250 to 300 years after the probe that found a suitable planet was launched and we try to recruit enough qualified people who would be willing to commit themselves and the next 5 generations of their progeny to a life limited to a spaceship.
Good luck finding SUITABLE candidates for that.
Worse, even if you did, and vetted the adults, how could you predict how the 2nd through 4th generations would take this? You know, the ones destined to die in space without ever leaving the confines of the prison their great great grandparents chose for them?
If I was in charge when the 2nd generation took over, I'm pretty sure I'd turn the craft around and say 'screw this', at least my grand kids get to grow up on a planet, not die in transit to a star we wouldn't even be sure we could live on.
The other huge question about a generational ship is how many people are needed?
See: http://www.physforum.com/index.php?showtop...ndpost&p=435459
And no, providing for just 100 people is WAY too small a number for a 200+ year voyage. You don't necessarily have to start with all you need to complete the jouney, but the number will be quite a bit bigger than 100.
In a generational ship, you have to allow for the elderly and the young (the elderly have to primarily teach and the young have an incredible amount to learn).
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and grow the food and recycle the O2 and the water and waste and provide the energy (can't use solar energy) and be able to repair any part of the ship and make the tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
Oh, and the generational craft's arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have to have been started by Ferdinand and Isabella.
And NO, that's not the same as building a sport arena.
Arthur
QUOTE (adoucette+Jan 18 2010, 01:48 PM)
It doesn't matter.
No one you know is ever going to go on an interstellar voyage.
There are only 6 yellow suns within 20 LYs of Earth, but 2 of those are binary stars and so are not suitable.
http://www.atlasoftheuniverse.com/20lys.html
Since I think it HIGHLY unlikely that we would ever manage a mission with an average speed greater than 0.1 c, and since it's not likely the planet you are looking for is closer than 20 LYs, so the shortest this mission is likely to be is a 200+ year mission.
At which point I think it's reasonable to ask, what's the point?
You aren't going to go off on a 200+ year mission without knowing your destination are you?
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
Ok, so now were lucky and its roughly 250 to 300 years after the probe that found a suitable planet was launched and we try to recruit enough qualified people who would be willing to commit themselves and the next 5 generations of their progeny to a life limited to a spaceship.
Good luck finding SUITABLE candidates for that.
Worse, even if you did, and vetted the adults, how could you predict how the 2nd through 4th generations would take this? You know, the ones destined to die in space without ever leaving the confines of the prison their great great grandparents chose for them?
If I was in charge when the 2nd generation took over, I'm pretty sure I'd turn the craft around and say 'screw this', at least my grand kids get to grow up on a planet, not die in transit to a star we wouldn't even be sure we could live on.
The other huge question about a generational ship is how many people are needed?
See: http://www.physforum.com/index.php?showtop...ndpost&p=435459
And no, providing for just 100 people is WAY too small a number for a 200+ year voyage. You don't necessarily have to start with all you need to complete the jouney, but the number will be quite a bit bigger than 100.
In a generational ship, you have to allow for the elderly and the young (the elderly have to primarily teach and the young have an incredible amount to learn).
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and grow the food and recycle the O2 and the water and waste and provide the energy (can't use solar energy) and be able to repair any part of the ship and make the tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
Oh, and the generational craft's arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have to have been started by Ferdinand and Isabella.
And NO, that's not the same as building a sport arena.
Arthur
LOL. at pretty much quoting your earlier post.
Yes, I know the ship has to support more than 100 people, but you should be able to start with as few as 100 (50 couples)or so.
Assuming average family size 4.3, the growth rate isn't too terrible.
Generational growth
*Linear approximations, not the exponential population growth formula.
100
~115
~133
~153
~176
~203
Total: ~880 max persons alive after 5 generations (again avg family size 4.3.)
But the definition of "generation" is nebulous, as anyone from a teenager to a 40-something can have children, and given human propensity for irrational behaviour, it would be difficult, if not impossible, to control for anything past the life spans of the original 100 individuals. That is, they may breed themselves out of resources even though they know they don't have enough food to sustain themselves.
No one you know is ever going to go on an interstellar voyage.
There are only 6 yellow suns within 20 LYs of Earth, but 2 of those are binary stars and so are not suitable.
http://www.atlasoftheuniverse.com/20lys.html
Since I think it HIGHLY unlikely that we would ever manage a mission with an average speed greater than 0.1 c, and since it's not likely the planet you are looking for is closer than 20 LYs, so the shortest this mission is likely to be is a 200+ year mission.
At which point I think it's reasonable to ask, what's the point?
You aren't going to go off on a 200+ year mission without knowing your destination are you?
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
Ok, so now were lucky and its roughly 250 to 300 years after the probe that found a suitable planet was launched and we try to recruit enough qualified people who would be willing to commit themselves and the next 5 generations of their progeny to a life limited to a spaceship.
Good luck finding SUITABLE candidates for that.
Worse, even if you did, and vetted the adults, how could you predict how the 2nd through 4th generations would take this? You know, the ones destined to die in space without ever leaving the confines of the prison their great great grandparents chose for them?
If I was in charge when the 2nd generation took over, I'm pretty sure I'd turn the craft around and say 'screw this', at least my grand kids get to grow up on a planet, not die in transit to a star we wouldn't even be sure we could live on.
The other huge question about a generational ship is how many people are needed?
See: http://www.physforum.com/index.php?showtop...ndpost&p=435459
And no, providing for just 100 people is WAY too small a number for a 200+ year voyage. You don't necessarily have to start with all you need to complete the jouney, but the number will be quite a bit bigger than 100.
In a generational ship, you have to allow for the elderly and the young (the elderly have to primarily teach and the young have an incredible amount to learn).
Once you figure this out, then figure out how massive this craft would have to be to house that many people, and grow the food and recycle the O2 and the water and waste and provide the energy (can't use solar energy) and be able to repair any part of the ship and make the tools they would need, PLUS the landing craft that could take it all to the surface once they get there.
Oh, and the generational craft's arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have to have been started by Ferdinand and Isabella.
And NO, that's not the same as building a sport arena.
Arthur
LOL. at pretty much quoting your earlier post.
Yes, I know the ship has to support more than 100 people, but you should be able to start with as few as 100 (50 couples)or so.
Assuming average family size 4.3, the growth rate isn't too terrible.
Generational growth
*Linear approximations, not the exponential population growth formula.
100
~115
~133
~153
~176
~203
Total: ~880 max persons alive after 5 generations (again avg family size 4.3.)
But the definition of "generation" is nebulous, as anyone from a teenager to a 40-something can have children, and given human propensity for irrational behaviour, it would be difficult, if not impossible, to control for anything past the life spans of the original 100 individuals. That is, they may breed themselves out of resources even though they know they don't have enough food to sustain themselves.
QUOTE
Total: ~880 max persons alive after 5 generations (again avg family size 4.3.)
Yeah, well that's a problem though isn't it.
Roughly speaking it takes about 25,000 sq ft at an absolute MINIMUM of FERTILE land and good sun and good rain to feed a person for a year.
In space, where we don't have seasons, let's cut that in HALF, and say we can get by on 12,500 sq ft of space, which is over 250 acres of intense crops and animals you have to heat, light, water and manage.
Which is just ONE of the reasons you won't get by with just your 800 people.
Farming, food preservation, animal husbandry and packaging would take a lot of manpower just by itself
There are just too many skills needed to keep a totally self reliant super high tech vessel going for 200+ years to be handled by just 800 people. Considering the number that are too old and too young to contribute, but require care, and an amazing amount of care and time expended on the young, who have to be raised and then taught on a HIGH PRESSURE curriculum to take over as the next generation.
Arthur
QUOTE
So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile.
This was discussed by myself and others previously. With existing transmitter technology you would need a relay of probes due to signal degradation. So in order to probe a planet at 20ly, you need about 15-20 relays a lightyear or so distant from one another, OR you need one probe with a VERY powerful laser-based transmitter. It also needs redundant backups of the transmitter in case of a mechanical malfunction OR self repairing mechanisms...but then...the self repair mechanisms need backups too...(nano-robots.)
QUOTE (->
| QUOTE |
| So the next pre-req is the ability to build an incredibly complex probe that can reliably operate autonomously for over 200 years, land on the planet and also communicate over a 20+ LY distance back to the earth, while at the same time making it as light as possible in order to get it to go as fast as possible on a given amount of fuel. That's going to take awhile. |
This was discussed by myself and others previously. With existing transmitter technology you would need a relay of probes due to signal degradation. So in order to probe a planet at 20ly, you need about 15-20 relays a lightyear or so distant from one another, OR you need one probe with a VERY powerful laser-based transmitter. It also needs redundant backups of the transmitter in case of a mechanical malfunction OR self repairing mechanisms...but then...the self repair mechanisms need backups too...(nano-robots.)
Oh, and the generational craft's arrival would be about 500+ years after the first successful probe was launched, or to put it in perspective, if you were on the ship, the program would have to have been started by Ferdinand and Isabella.
Yet, Columbus sailed across the atlantic using technology so relatively primitive compared to modern standards, that most of us have FORGOTTEN how to even make a ship that primitive...
===
Ok, so anyone who is advanced enough to make such a probe, and to make a generational ship as here described, would no longer need a planet to live on in the first place. Such a civilization would simply need enough material at the destination star to make Dyson Swarms, and they may actually be better served looking for stars that don't have planets at all, but rather stars with very large belts of asteroids and comets which can be easily harvested to produce new artificial environments.
After all, if you've solved the problem of a ~200-300 year voyage through space, landing the colony ship on the surface of a planet is a dumb move and a waste of energy(not that energy would even matter much, I suppose.) As having survived without a planet for 200-300 years, it would certainly have met or exceeded the needs of my orbital platforms, and could then continue to serve in that function for a new Type 2 Dyson Swarm civilization at the new star, without the need for a planet anyway.
So if you can't build a "self sustaining" orbital platform or Dyson Swarm that survives by solar power and mining asteroids and comets, then you definitely cannot build an interstellar colony ship that survives by anti-matter power...
The Dyson Swarm is absolutely a pre-requisite for making a colony ship, because it shares every technology except possibly propulsion and on-board power.
QUOTE (Quantum_Conundrum+Jan 18 2010, 03:08 PM)
This was discussed by myself and others previously. With existing transmitter technology you would need a relay of probes due to signal degradation. So in order to probe a planet at 20ly, you need about 15-20 relays a lightyear or so distant from one another, OR you need one probe with a VERY powerful laser-based transmitter. It also needs redundant backups of the transmitter in case of a mechanical malfunction OR self repairing mechanisms...but then...the self repair mechanisms need backups too...(nano-robots.)
Too risky.
Lose one, lose them all.
And NO, you couldn't expect it to repair itself.
The safe bet is the ONE BIG transmitter, but that just adds to the weight and complexity of the probe.
Which is what you don't want.
Face it, you won't hear a peep from this thing after its a few LYs from earth.
To put it in perspective, it takes quite a bit to still pick up Voyager, but its only ~ 100 AU from earth.
A light year is over 63,000 AU.
Arthur
QUOTE (adoucette+Jan 18 2010, 03:07 PM)
Yeah, well that's a problem though isn't it.
Roughly speaking it takes about 25,000 sq ft at an absolute MINIMUM of FERTILE land and good sun and good rain to feed a person for a year.
In space, where we don't have seasons, let's cut that in HALF, and say we can get by on 12,500 sq ft of space, which is over 250 acres of intense crops and animals you have to heat, light, water and manage.
Which is just ONE of the reasons you won't get by with just your 800 people.
Farming, food preservation, animal husbandry and packaging would take a lot of manpower just by itself
There are just too many skills needed to keep a totally self reliant super high tech vessel going for 200+ years to be handled by just 800 people. Considering the number that are too old and too young to contribute, but require care, and an amazing amount of care and time expended on the young, who have to be raised and then taught on a HIGH PRESSURE curriculum to take over as the next generation.
Arthur
I'm not downplaying the issue, but most plants in nature, including our primary crops, are not terribly efficient in open fields. Tomatoes in modern greenhouses grow as much as 16 times more marketable food content. In addition, due to shipping reasons, everything except the absolute best tomatoes are thrown away, even though most of the discarded food is edible and could be canned if there was a cannery on site...
I have seen demonstrations on growing sweet potatoes and peanuts which show that they can be grown in a nutrient solution with no soil at all, and possibly for a lower price per yield than traditional farming, (which is why research was being done on that.)
You don't have droughts, floods, or pests* to deal with, and even pollenation might be handled through automated systems, such that every flower gets pollenated and the maximum yield is given.
* If you have nano-technology, you do not need even most of the "beneficial" life forms in earth-bound ecosystems. Your programmable nano-machines do the pollenation, and as much as possible, they also even do the recycling of materials.
** on the other hand, you would still want to bring along enough revivable DNA to produce a permanent, stable ecosystem "somewhere"....
*** this is certainly a stretch, but it may be possible for nano-machines to mass produce synthetic foods which are indistinguishable from "natural" crops. While this appears too "trekky" it should theoretically be possible in many cases. Moore's law suggests this may actually be one of the EASIER solutions to any of ht eproblems related to space flight, because computers should be small enough and powerful enough to allow Borg style nano-scale robots within about 30-40 years. This would allow controlled manufacturing of food on a molecule by molecule basis, with an absolute minimum of waste.
With existing methods, crops to support 880 people equates to about 2km worth of floor space. But with the greenhouse concept, you could also have "hanging gardens" maximizing the efficiency of each given portion of floor space, which is not terribly significant for many crops, but worth mentioning for some.
still, floor space is a serious problem because 2km is already more than the largest existing sky scrapers...
QUOTE (adoucette+Jan 18 2010, 03:18 PM)
Too risky.
Lose one, lose them all.
And NO, you couldn't expect it to repair itself.
The safe bet is the ONE BIG transmitter, but that just adds to the weight and complexity of the probe.
Which is what you don't want.
Face it, you won't hear a peep from this thing after its a few LYs from earth.
To put it in perspective, it takes quite a bit to still pick up Voyager, but its only ~ 100 AU from earth.
A light year is over 63,000 AU.
Arthur
Yes, but Voyager's primary mission was not deep space exploration. It was designed primarily for planetary fly-by, everything else was basicly just "bonus".
Lose one, lose them all.
And NO, you couldn't expect it to repair itself.
The safe bet is the ONE BIG transmitter, but that just adds to the weight and complexity of the probe.
Which is what you don't want.
Face it, you won't hear a peep from this thing after its a few LYs from earth.
To put it in perspective, it takes quite a bit to still pick up Voyager, but its only ~ 100 AU from earth.
A light year is over 63,000 AU.
Arthur
Yes, but Voyager's primary mission was not deep space exploration. It was designed primarily for planetary fly-by, everything else was basicly just "bonus".
QUOTE (Quantum_Conundrum+Jan 18 2010, 03:39 PM)
Yes, but Voyager's primary mission was not deep space exploration. It was designed primarily for planetary fly-by, everything else was basicly just "bonus".
Doesn't matter.
Voyager WAS designed for deep space transmission of data, but since the signal strength is inversely proportional to the square of the distance from the source, when you are 1 LY away, you will need 400,000 times the power to get the same signal as we get from Voyager.
2 LY is totally nuts.
You could go with a laser, but to keep a laser beam very well collimated, it must have a large diameter, and a LOT of power.
Nope, not a peep.
Arthur
Doesn't matter.
Voyager WAS designed for deep space transmission of data, but since the signal strength is inversely proportional to the square of the distance from the source, when you are 1 LY away, you will need 400,000 times the power to get the same signal as we get from Voyager.
2 LY is totally nuts.
You could go with a laser, but to keep a laser beam very well collimated, it must have a large diameter, and a LOT of power.
Nope, not a peep.
Arthur
Don't want to put a price tag on human life, because that's sort of the whole point here...BUT...
...IF a probe becomes more complex than a human being, then it is no longer significantly "easier" to send across space than a manned vessel, because it becomes just as likely to malfunction as the human being is to get sick or die.
If you have billions of parts (which the computers alone have,) odds are very, very high of those parts breaking down even over a matter of a few years or decades.
Clearly, we are going to be at the absolute limits of even THEORETICAL computer and robotics technologies LONG before an actual inter stellar probe is ever constructed.
The probe will either need very near human intelligence, or else it will need possibly billions of lines of contingency programming to handle every reasonable scenario.
...IF a probe becomes more complex than a human being, then it is no longer significantly "easier" to send across space than a manned vessel, because it becomes just as likely to malfunction as the human being is to get sick or die.
If you have billions of parts (which the computers alone have,) odds are very, very high of those parts breaking down even over a matter of a few years or decades.
Clearly, we are going to be at the absolute limits of even THEORETICAL computer and robotics technologies LONG before an actual inter stellar probe is ever constructed.
The probe will either need very near human intelligence, or else it will need possibly billions of lines of contingency programming to handle every reasonable scenario.
QUOTE (adoucette+Jan 18 2010, 03:50 PM)
Doesn't matter.
Voyager WAS designed for deep space transmission of data, but since the signal strength is inversely proportional to the square of the distance from the source, when you are 1 LY away, you will need 400,000 times the power to get the same signal as we get from Voyager.
2 LY is totally nuts.
You could go with a laser, but to keep a laser beam very well collimated, it must have a large diameter, and a LOT of power.
Nope, not a peep.
Arthur
We've discussed signal degradation on this forum before, which is why it was determined that very few solutions existed.
Some have already been mentioned
Relay:
No specific distances were determined. We simply guesstimated that they would be needed about every 1 to 2 ly. We (myself and others discussing this,) knew that the signal degraded, and that there would need to be a network of probes with Earth being the hub connecting civilization throughout the galaxy.
Laser:
The assumption was that these would be very, very powerful. They would be powered by Dyson Megastructures to eventually communicate between Dyson Swarm/Sphere civilizations on distant stars for the purpose of sharing any new breakthrough discoveries.
This assumes anything remaining worth discovering to a civilization already capable of building these devices...Zero Point Modulus, Time Travel, Perpetual motion maybe....all highly unlikely...
Voyager WAS designed for deep space transmission of data, but since the signal strength is inversely proportional to the square of the distance from the source, when you are 1 LY away, you will need 400,000 times the power to get the same signal as we get from Voyager.
2 LY is totally nuts.
You could go with a laser, but to keep a laser beam very well collimated, it must have a large diameter, and a LOT of power.
Nope, not a peep.
Arthur
We've discussed signal degradation on this forum before, which is why it was determined that very few solutions existed.
Some have already been mentioned
Relay:
No specific distances were determined. We simply guesstimated that they would be needed about every 1 to 2 ly. We (myself and others discussing this,) knew that the signal degraded, and that there would need to be a network of probes with Earth being the hub connecting civilization throughout the galaxy.
Laser:
The assumption was that these would be very, very powerful. They would be powered by Dyson Megastructures to eventually communicate between Dyson Swarm/Sphere civilizations on distant stars for the purpose of sharing any new breakthrough discoveries.
This assumes anything remaining worth discovering to a civilization already capable of building these devices...Zero Point Modulus, Time Travel, Perpetual motion maybe....all highly unlikely...
QUOTE (Quantum_Conundrum+Jan 18 2010, 04:12 PM)
We've discussed signal degradation on this forum before, which is why it was determined that very few solutions existed.
Some have already been mentioned
Relay:
No specific distances were determined. We simply guesstimated that they would be needed about every 1 to 2 ly. We (myself and others discussing this,) knew that the signal degraded, and that there would need to be a network of probes with Earth being the hub connecting civilization throughout the galaxy.
Yes, but apparently you just blew smoke up each others skirts.
Again, put it in perspective based on some things we do know.
The RTG on Voyager puts out 1,880 watts of thermal energy from an RTG to produce 400 watts of electrical power and has a 3.7 meter directional antenna to send the signal to earth.
It's 100 AUs from Earth and we are near the limit of being able to listen to it.
But we COULD build a better antenna and we could put that in orbit, so for the sake of argument, let's say, we could with improved technology listen to Voyager even when it was up to 300 AUs from Earth (that's a HUGE improvement)
Which would mean we would need approx 120,000 times the signal strength, and also a massively larger antenna to handle that much power.
But let's say we double the efficiency of the antenna, so we only need 60,000 times the signal strength.
And let's say we triple the amount of electrical energy we can get from an RTG such that from an 1,800 watt RTG we can get 1,200 watts.
Even with those assumptions we need a sufficient RTGs to produces 36,000,000 watts of power.
Well, the Voyager units used Pu 238, and weighed 40 kg.
BUT you can't use Pu 238, because it's half life is only 87 years.
Americium 241 would probably be the choice, with a half life of 432 years, but it takes 4 times the weight as Pu 238 for the same energy, or roughly 3,200,000 kgs of Americium 241 (which we don't have).
YIKES.
And you want one of these every light year, for over 20 light years?
Like I said.
Not a peep.
Arthur
Some have already been mentioned
Relay:
No specific distances were determined. We simply guesstimated that they would be needed about every 1 to 2 ly. We (myself and others discussing this,) knew that the signal degraded, and that there would need to be a network of probes with Earth being the hub connecting civilization throughout the galaxy.
Yes, but apparently you just blew smoke up each others skirts.
Again, put it in perspective based on some things we do know.
The RTG on Voyager puts out 1,880 watts of thermal energy from an RTG to produce 400 watts of electrical power and has a 3.7 meter directional antenna to send the signal to earth.
It's 100 AUs from Earth and we are near the limit of being able to listen to it.
But we COULD build a better antenna and we could put that in orbit, so for the sake of argument, let's say, we could with improved technology listen to Voyager even when it was up to 300 AUs from Earth (that's a HUGE improvement)
Which would mean we would need approx 120,000 times the signal strength, and also a massively larger antenna to handle that much power.
But let's say we double the efficiency of the antenna, so we only need 60,000 times the signal strength.
And let's say we triple the amount of electrical energy we can get from an RTG such that from an 1,800 watt RTG we can get 1,200 watts.
Even with those assumptions we need a sufficient RTGs to produces 36,000,000 watts of power.
Well, the Voyager units used Pu 238, and weighed 40 kg.
BUT you can't use Pu 238, because it's half life is only 87 years.
Americium 241 would probably be the choice, with a half life of 432 years, but it takes 4 times the weight as Pu 238 for the same energy, or roughly 3,200,000 kgs of Americium 241 (which we don't have).
YIKES.
And you want one of these every light year, for over 20 light years?
Like I said.
Not a peep.
Arthur
QUOTE (adoucette+Jan 18 2010, 04:43 PM)
Yes, but apparently you just blew smoke up each others skirts.
Again, put it in perspective based on some things we do know.
The RTG on Voyager puts out 1,880 watts of thermal energy from an RTG to produce 400 watts of electrical power and has a 3.7 meter directional antenna to send the signal to earth.
It's 100 AUs from Earth and we are near the limit of being able to listen to it.
But we COULD build a better antenna and we could put that in orbit, so for the sake of argument, let's say, we could with improved technology listen to Voyager even when it was up to 300 AUs from Earth (that's a HUGE improvement)
Which would mean we would need approx 120,000 times the signal strength, and also a massively larger antenna to handle that much power.
But let's say we double the efficiency of the antenna, so we only need 60,000 times the signal strength.
And let's say we triple the amount of electrical energy we can get from an RTG such that from an 1,800 watt RTG we can get 1,200 watts.
Even with those assumptions we need a sufficient RTGs to produces 36,000,000 watts of power.
Well, the Voyager units used Pu 238, and weighed 40 kg.
BUT you can't use Pu 238, because it's half life is only 87 years.
Americium 241 would probably be the choice, with a half life of 432 years, but it takes 4 times the weight as Pu 238 for the same energy, or roughly 3,200,000 kgs of Americium 241 (which we don't have).
YIKES.
And you want one of these every light year, for over 20 light years?
Like I said.
Not a peep.
Arthur
Then lasers it is...
But then even if you solve the power requirements for a laser you then have alignment problems. Earth isn't going to be in the path of the laser full time due to orbit around the sun, unless the target planet is significantly above or below the plane of earth orbit.
Again, put it in perspective based on some things we do know.
The RTG on Voyager puts out 1,880 watts of thermal energy from an RTG to produce 400 watts of electrical power and has a 3.7 meter directional antenna to send the signal to earth.
It's 100 AUs from Earth and we are near the limit of being able to listen to it.
But we COULD build a better antenna and we could put that in orbit, so for the sake of argument, let's say, we could with improved technology listen to Voyager even when it was up to 300 AUs from Earth (that's a HUGE improvement)
Which would mean we would need approx 120,000 times the signal strength, and also a massively larger antenna to handle that much power.
But let's say we double the efficiency of the antenna, so we only need 60,000 times the signal strength.
And let's say we triple the amount of electrical energy we can get from an RTG such that from an 1,800 watt RTG we can get 1,200 watts.
Even with those assumptions we need a sufficient RTGs to produces 36,000,000 watts of power.
Well, the Voyager units used Pu 238, and weighed 40 kg.
BUT you can't use Pu 238, because it's half life is only 87 years.
Americium 241 would probably be the choice, with a half life of 432 years, but it takes 4 times the weight as Pu 238 for the same energy, or roughly 3,200,000 kgs of Americium 241 (which we don't have).
YIKES.
And you want one of these every light year, for over 20 light years?
Like I said.
Not a peep.
Arthur
Then lasers it is...
But then even if you solve the power requirements for a laser you then have alignment problems. Earth isn't going to be in the path of the laser full time due to orbit around the sun, unless the target planet is significantly above or below the plane of earth orbit.
I think lasers add more problems then they solve.
Maintaining alignment from 1 LY away?
Not likely.
Not a peep.
Arthur
Maintaining alignment from 1 LY away?
Not likely.
Not a peep.
Arthur
I think your numbers are likely wrong regarding the maximum lifetime of the Voyager.
The wiki site states that communication will remain possible "at least" until 2025, which is another 15 years. In 15 years, the craft will increase it's distance by nearly another 50%, yet it's stated as "at least" 2025...which implies the possibility of some lengthening by making a better reciever...
Of course, they are killing it slowly with system shutdowns...
But I mean...look at what that thing is compared to modern computers? Do you realize every person on earth has a computer and camera about as advanced as any one instrument on the craft? Much more powerful in many cases.
We could send...a cell phone...to do the same job next time...Well, almost....
Also, you haven't considered a fusion or anti-matter power plant or hybrid power plant solution for the probe. Fusion is about 100 times as energy dense as fision, and doesn't necessarily have the "half life use it or lose it" problem.
The wiki site states that communication will remain possible "at least" until 2025, which is another 15 years. In 15 years, the craft will increase it's distance by nearly another 50%, yet it's stated as "at least" 2025...which implies the possibility of some lengthening by making a better reciever...
Of course, they are killing it slowly with system shutdowns...
But I mean...look at what that thing is compared to modern computers? Do you realize every person on earth has a computer and camera about as advanced as any one instrument on the craft? Much more powerful in many cases.
We could send...a cell phone...to do the same job next time...Well, almost....
Also, you haven't considered a fusion or anti-matter power plant or hybrid power plant solution for the probe. Fusion is about 100 times as energy dense as fision, and doesn't necessarily have the "half life use it or lose it" problem.
QUOTE (Quantum_Conundrum+Jan 18 2010, 05:48 PM)
I think your numbers are likely wrong regarding the maximum lifetime of the Voyager.
The wiki site states that communication will remain possible "at least" until 2025, which is another 15 years. In 15 years, the craft will increase it's distance by nearly another 50%, yet it's stated as "at least" 2025...which implies the possibility of some lengthening by making a better reciever...
Of course, they are killing it slowly with system shutdowns...
But I mean...look at what that thing is compared to modern computers? Do you realize every person on earth has a computer and camera about as advanced as any one instrument on the craft? Much more powerful in many cases.
We could send...a cell phone...to do the same job next time...Well, almost....
Also, you haven't considered a fusion or anti-matter power plant or hybrid power plant solution for the probe. Fusion is about 100 times as energy dense as fision, and doesn't necessarily have the "half life use it or lose it" problem.
In 2025 Voyager will be about 150 AU.
I said we could assume with improvements in the antenna we could hear it out to 300 AU, or a 100% improvement over when we think we will last be able to hear from it.
I also said we would get 300% more energy per pound from the RTGs (and RTGs, per pound are the most efficient energy source we have today, which is WHY we use them on deep space probes, you can fantisize about more dense energy supplies, but you can't wish them into being)
I also said we would increase the antenna efficiency by 100%.
And that came up to 3,200,000 kgs of Americium 241.
None of that is related to advances in computers.
But what the heck, double the distance once more, out to 600 AU and double the antenna efficiency again by another 100%,
Big deal.
So now you only need 800,000 lbs of Americium 241, and an antenna maybe 200 meters across.
You STILL aren't going to build 20 of these massive structures and launch them at incredible individual cost just to be able to talk to 800 people who will most likely die along the way from critical system failures due to the inability to maintain them with no outside support/materials for 200 years.
Not a peep.
Arthur
The wiki site states that communication will remain possible "at least" until 2025, which is another 15 years. In 15 years, the craft will increase it's distance by nearly another 50%, yet it's stated as "at least" 2025...which implies the possibility of some lengthening by making a better reciever...
Of course, they are killing it slowly with system shutdowns...
But I mean...look at what that thing is compared to modern computers? Do you realize every person on earth has a computer and camera about as advanced as any one instrument on the craft? Much more powerful in many cases.
We could send...a cell phone...to do the same job next time...Well, almost....
Also, you haven't considered a fusion or anti-matter power plant or hybrid power plant solution for the probe. Fusion is about 100 times as energy dense as fision, and doesn't necessarily have the "half life use it or lose it" problem.
In 2025 Voyager will be about 150 AU.
I said we could assume with improvements in the antenna we could hear it out to 300 AU, or a 100% improvement over when we think we will last be able to hear from it.
I also said we would get 300% more energy per pound from the RTGs (and RTGs, per pound are the most efficient energy source we have today, which is WHY we use them on deep space probes, you can fantisize about more dense energy supplies, but you can't wish them into being)
I also said we would increase the antenna efficiency by 100%.
And that came up to 3,200,000 kgs of Americium 241.
None of that is related to advances in computers.
But what the heck, double the distance once more, out to 600 AU and double the antenna efficiency again by another 100%,
Big deal.
So now you only need 800,000 lbs of Americium 241, and an antenna maybe 200 meters across.
You STILL aren't going to build 20 of these massive structures and launch them at incredible individual cost just to be able to talk to 800 people who will most likely die along the way from critical system failures due to the inability to maintain them with no outside support/materials for 200 years.
Not a peep.
Arthur
http://math.ucr.edu/home/baez/physics/Rela.../SR/rocket.html
When we return to these forumlae, they are assuming constant acceleration, both positive and negative, which is only "realistic" to a civilization with near-infinite energy capabilities.
It is much more realistic and practical to pick a target velocity high enough to make the biosphere and it's power supply reasonably plausible, and then coast to the "braking point", before slowing down.
Using the formula from this web site, for "low" relativistic values of V, we have.
V = velocity
M = mass of "stoppage" fuel in ideal anti-matter engine
m = mass of payload
M' = mass of accelerating fuel
N = Total Fuel
* note that all numbers are rounded UP at 4th decimal.
V = 0.1c, M = 0.1055m, M' = 0.1166m, N = 0.2221m
V = 0.2c, M = 0.2247m, M' = 0.2752m, N = 0.4999m
V = 0.3c, M = 0.3628m, M' = 0.4945m, N = 0.8573m
V = 0.4c, M = 0.5276m, M' = 0.8060m, N = 1.3336m
V = 0.5c, M = 0.7321m, M' = 1.2681m, N = 2.0002m
So, with ideal antimatter engines, you could accelerate and stop a ship ~9 times larger to 0.1c as compared to 0.5 c, for the same total energy.
We may surmised that the survivability, s, of the colony ship is some function of inverse time and all obstacles, O, also differentiated with respect to time, because the longer the mission the harder to survive.
s(t) = (f(O))/t
Now if we shorten the time, it's obvious the survivability goes up roughly AT LEAST linearly.
But in order to shorten the time costs exponentially more fuel. At some point, given a large enough ship and efficient enough internal technologies, we may be reasonably sure that it is actually easier to keep the ship and biosphere functioning for a longer period of time than it would be to further accelerate the ship.
Example:
Given the progression above, it may literally be easier to move a "Sealed Environments, type 1 civlization" on the surface of a moon with the right properties, than to make a "star ship". Let's take Enceladus, for example.
It has insane amounts of water, and probably a rocky core. It has respectable gravity, but not earth-like. This means that there are resources enough on the planet to prouduce fusion power for eons and eons, sufficient for the people living on it. This also means that the entire planet is covered in a fuel source for a direct fusion-based propulsion.
If you could get the entire moon moving at a relatively low speed, such as only a few hundred kilometers per second, as opposed to more relativistic speeds, the moon has enough energy (through controlled fusion) to support life for ages upon ages, for the same reason earth has: size. We know Enceladus has water, nitrogen, and carbon dioxide.
So if you moved the moon at 300km/s (0.001c), it would take ~20,000 years to reach the nearest star with a known planet. The amount of water on Enceladus would permit fusion for normal life purposes and normal civilization usage for billions of years actually.
Now to see if this is even possible.
Enceladus has a mass of 1.08022*10^20kg
Fusing 200kg of hydrogen equates to about 1kg of anti-matter.
According to that formula, to get Enceladus to 0.001c would take
M = 0.001m worth of anti-matter in an ideal engine
or
0.2m worth of hydrogen fusion in an ideal engine*
* not possible because by percentage, this is more than the mass of hydrogen on Enceladus.
Soooo....scale down another tenth of velocity.
v = 30km/s = 0.0001c, time = 200,000yrs
M ~ 0.0001m worth of antimatter
or
M ~ 0.020001m worth of hydrogen fusion.
M' ~0.020001m worth of hydrogen fusion
N ~ 0.040002m worth of hydrogen fusion
This MIGHT actually be doable, in theory, depending on the exact percentage of Enceladus' mass which comes from water, because by mass, water is 1/9 (or 11.11 percent) hydrogen, and 4 percent total lunar mass gives us approximately a factor of 2.75 to work with.
So Enceladus is large enough to support sentient life for geologic time periods through fusion of water, but small enough to be accelerated to a high enough speed to reach a distant star, at least in many, many ten thousands of years....using only materials on Enceladus (plus stuff imported from asteroid field ot make the actual habitats and engines.)
So at least this tells us one thing, even an artificial worldship with an ideal fusion engine (which may be easier and safer than antimatter) would be at least four percent "fusion rocket fuel" (hydrogen) by mass...and this is allowing the assuming that it is "big enough" to be self sustaining for the duration through an environment powered by controlled fusion life support.
If anti-matter could be processed from Enceladus and used in a purely artificial world ship, this would decrease the fuel mass to ship mass ratio by 200(ideal antimatter vs ideal fusion), or give 1/500th of the mass of the ship itself....this to obtain 30Km/s and require 200,000 years to reach the nearest star with a known planet....
An artificial world ship might be something as big as the Death Star I, and if it used anti-matter, it might be able to go as much as 10-100 times faster...
A cylinder with radius equal to the Death Star I and height equal to it's diameter would have mass significantly less than Asteriod Ceres, and "floor space" of as much as 32.5 million km^2 (6.36% surface area of earth). Even if a full 90% of the volume is dedicated to engines and fuel, that would still leavel about 3.25 million km^2 of floor space, or over half a percent of earth's surface area.
This should also be large enough to contain enough resources to support human beings across geologic time scales.
When we return to these forumlae, they are assuming constant acceleration, both positive and negative, which is only "realistic" to a civilization with near-infinite energy capabilities.
It is much more realistic and practical to pick a target velocity high enough to make the biosphere and it's power supply reasonably plausible, and then coast to the "braking point", before slowing down.
Using the formula from this web site, for "low" relativistic values of V, we have.
V = velocity
M = mass of "stoppage" fuel in ideal anti-matter engine
m = mass of payload
M' = mass of accelerating fuel
N = Total Fuel
* note that all numbers are rounded UP at 4th decimal.
V = 0.1c, M = 0.1055m, M' = 0.1166m, N = 0.2221m
V = 0.2c, M = 0.2247m, M' = 0.2752m, N = 0.4999m
V = 0.3c, M = 0.3628m, M' = 0.4945m, N = 0.8573m
V = 0.4c, M = 0.5276m, M' = 0.8060m, N = 1.3336m
V = 0.5c, M = 0.7321m, M' = 1.2681m, N = 2.0002m
So, with ideal antimatter engines, you could accelerate and stop a ship ~9 times larger to 0.1c as compared to 0.5 c, for the same total energy.
We may surmised that the survivability, s, of the colony ship is some function of inverse time and all obstacles, O, also differentiated with respect to time, because the longer the mission the harder to survive.
s(t) = (f(O))/t
Now if we shorten the time, it's obvious the survivability goes up roughly AT LEAST linearly.
But in order to shorten the time costs exponentially more fuel. At some point, given a large enough ship and efficient enough internal technologies, we may be reasonably sure that it is actually easier to keep the ship and biosphere functioning for a longer period of time than it would be to further accelerate the ship.
Example:
Given the progression above, it may literally be easier to move a "Sealed Environments, type 1 civlization" on the surface of a moon with the right properties, than to make a "star ship". Let's take Enceladus, for example.
It has insane amounts of water, and probably a rocky core. It has respectable gravity, but not earth-like. This means that there are resources enough on the planet to prouduce fusion power for eons and eons, sufficient for the people living on it. This also means that the entire planet is covered in a fuel source for a direct fusion-based propulsion.
If you could get the entire moon moving at a relatively low speed, such as only a few hundred kilometers per second, as opposed to more relativistic speeds, the moon has enough energy (through controlled fusion) to support life for ages upon ages, for the same reason earth has: size. We know Enceladus has water, nitrogen, and carbon dioxide.
So if you moved the moon at 300km/s (0.001c), it would take ~20,000 years to reach the nearest star with a known planet. The amount of water on Enceladus would permit fusion for normal life purposes and normal civilization usage for billions of years actually.
Now to see if this is even possible.
Enceladus has a mass of 1.08022*10^20kg
Fusing 200kg of hydrogen equates to about 1kg of anti-matter.
According to that formula, to get Enceladus to 0.001c would take
M = 0.001m worth of anti-matter in an ideal engine
or
0.2m worth of hydrogen fusion in an ideal engine*
* not possible because by percentage, this is more than the mass of hydrogen on Enceladus.
Soooo....scale down another tenth of velocity.
v = 30km/s = 0.0001c, time = 200,000yrs
M ~ 0.0001m worth of antimatter
or
M ~ 0.020001m worth of hydrogen fusion.
M' ~0.020001m worth of hydrogen fusion
N ~ 0.040002m worth of hydrogen fusion
This MIGHT actually be doable, in theory, depending on the exact percentage of Enceladus' mass which comes from water, because by mass, water is 1/9 (or 11.11 percent) hydrogen, and 4 percent total lunar mass gives us approximately a factor of 2.75 to work with.
So Enceladus is large enough to support sentient life for geologic time periods through fusion of water, but small enough to be accelerated to a high enough speed to reach a distant star, at least in many, many ten thousands of years....using only materials on Enceladus (plus stuff imported from asteroid field ot make the actual habitats and engines.)
So at least this tells us one thing, even an artificial worldship with an ideal fusion engine (which may be easier and safer than antimatter) would be at least four percent "fusion rocket fuel" (hydrogen) by mass...and this is allowing the assuming that it is "big enough" to be self sustaining for the duration through an environment powered by controlled fusion life support.
If anti-matter could be processed from Enceladus and used in a purely artificial world ship, this would decrease the fuel mass to ship mass ratio by 200(ideal antimatter vs ideal fusion), or give 1/500th of the mass of the ship itself....this to obtain 30Km/s and require 200,000 years to reach the nearest star with a known planet....
An artificial world ship might be something as big as the Death Star I, and if it used anti-matter, it might be able to go as much as 10-100 times faster...
A cylinder with radius equal to the Death Star I and height equal to it's diameter would have mass significantly less than Asteriod Ceres, and "floor space" of as much as 32.5 million km^2 (6.36% surface area of earth). Even if a full 90% of the volume is dedicated to engines and fuel, that would still leavel about 3.25 million km^2 of floor space, or over half a percent of earth's surface area.
This should also be large enough to contain enough resources to support human beings across geologic time scales.
QUOTE
If you could get the entire moon moving at a relatively low speed, such as only a few hundred kilometers per second
Saturn might object.
Arthur
Constructing a world ship may be beyond the capabilities of even a "True" type 1 civilization.
It may require the production infrastructure equivalent to several Type 1 civilizations, which would mean it would likely be impossible without first colonizing every major body in the solar system which can be colonized, and populating those to their maximum capacity, either with humans or robots, in order to obtain the production capabilities needed even over relatively long time spans such as hundreds of years.
A fully populated Mars would be able to contribute far easier than earth, due to lower gravity.
Fully populated Dyson Swarms would also be able to contribute easier than Earth or Mars...
Just like Dyson Swarms, Most material would need to come from asteriods and comets, else the production energy costs would begin to become significant compared to fuel costs per payload...
It may require the production infrastructure equivalent to several Type 1 civilizations, which would mean it would likely be impossible without first colonizing every major body in the solar system which can be colonized, and populating those to their maximum capacity, either with humans or robots, in order to obtain the production capabilities needed even over relatively long time spans such as hundreds of years.
A fully populated Mars would be able to contribute far easier than earth, due to lower gravity.
Fully populated Dyson Swarms would also be able to contribute easier than Earth or Mars...
Just like Dyson Swarms, Most material would need to come from asteriods and comets, else the production energy costs would begin to become significant compared to fuel costs per payload...
Right, and in my 200th reincarnation, maybe I'll get to see how this is coming.
Arthur
Arthur
New science discoveries, such as solving the "Pioneer anomaly" (which the New Horizon craft has plenty of equipment to do, and it is well on its way to Pluto/Kuiper Belt). My name is on a disk on that craft...
With the right understanding of future engine/rocket design methods, that one may someday (hopefully soon, as we wish to be living to witness it) such a system that will outpace the distance of the Voyager crafts, pass them by (I will not venture a "stop and reclamation parts robbing" of their antiquated equipment!).
They seem better than ever at improving these craft, with no end in sight of such continuing advancements...
With the right understanding of future engine/rocket design methods, that one may someday (hopefully soon, as we wish to be living to witness it) such a system that will outpace the distance of the Voyager crafts, pass them by (I will not venture a "stop and reclamation parts robbing" of their antiquated equipment!).
They seem better than ever at improving these craft, with no end in sight of such continuing advancements...
I just read that Kepler has detected two planet-sized objects in fast orbits around their suns which are hotter than the suns they are orbiting. I assume these were the objects referred to as beyond what the scientists could have predicted.
Very interesting.
Very interesting.
QUOTE (gocrew+Apr 1 2010, 11:03 PM)
I just read that Kepler has detected two planet-sized objects in fast orbits around their suns which are hotter than the suns they are orbiting. I assume these were the objects referred to as beyond what the scientists could have predicted.
Very interesting.
Hi,
Can you link the article?
Very interesting.
Hi,
Can you link the article?
QUOTE (Matador+Apr 2 2010, 04:18 AM)
Hi,
Can you link the article?
I started at the wikipedia entry for 'Kepler', and there you can find several linked articles.
http://en.wikipedia.org/wiki/Kepler_Mission
Can you link the article?
I started at the wikipedia entry for 'Kepler', and there you can find several linked articles.
http://en.wikipedia.org/wiki/Kepler_Mission
QUOTE (gocrew+Apr 3 2010, 03:33 AM)
I started at the wikipedia entry for 'Kepler', and there you can find several linked articles.
http://en.wikipedia.org/wiki/Kepler_Mission
Thank you.
http://en.wikipedia.org/wiki/Kepler_Mission
Thank you.
QUOTE (gocrew+Apr 1 2010, 08:03 AM)
I just read that Kepler has detected two planet-sized objects in fast orbits around their suns which are hotter than the suns they are orbiting. I assume these were the objects referred to as beyond what the scientists could have predicted.
Very interesting.
I don't think this is something that was beyond what scientists would have predicted as companion stars are fairly common and of course Kepler's secondary mission was to categorize star types .
KOI-74b is a 12,000 K hot companion of KOI-74 (KIC 6889235), a 9,400 K early A-type main sequence star in the constellation Cygnus.
KOI-81b is a 13,000 K hot companion of KOI-81 (KIC 8823868), a 10,000 K late B-type main sequence star in the constellation Cygnus.
The two transiting objects which have radii similar to Jupiter and effective temperatures > 10000 K.
KOI-74b may have properties similar a low-mass white dwarfs, in that it is compact and hot and its radius combined with a rough estimate of its mass is consistent with an internal structure dominated by electron degeneracy.
KOI-81b has a radius consistent with either a late M-dwarf, brown
dwarf or Jupiter-sized planet, but this picture is inconsistent with its observed temperature.
http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.3420v3.pdf
As to the poll, here's their discovery page:
http://kepler.nasa.gov/Mission/discoveries/
As of yet, nothing that would be classified as a rocky earth like planet.
Still, considering their longer transit time, the first discovery of a rocky planet in the habitable zone may take another year.
Arthur
Very interesting.
I don't think this is something that was beyond what scientists would have predicted as companion stars are fairly common and of course Kepler's secondary mission was to categorize star types .
KOI-74b is a 12,000 K hot companion of KOI-74 (KIC 6889235), a 9,400 K early A-type main sequence star in the constellation Cygnus.
KOI-81b is a 13,000 K hot companion of KOI-81 (KIC 8823868), a 10,000 K late B-type main sequence star in the constellation Cygnus.
The two transiting objects which have radii similar to Jupiter and effective temperatures > 10000 K.
KOI-74b may have properties similar a low-mass white dwarfs, in that it is compact and hot and its radius combined with a rough estimate of its mass is consistent with an internal structure dominated by electron degeneracy.
KOI-81b has a radius consistent with either a late M-dwarf, brown
dwarf or Jupiter-sized planet, but this picture is inconsistent with its observed temperature.
http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.3420v3.pdf
As to the poll, here's their discovery page:
http://kepler.nasa.gov/Mission/discoveries/
As of yet, nothing that would be classified as a rocky earth like planet.
Still, considering their longer transit time, the first discovery of a rocky planet in the habitable zone may take another year.
Arthur
Arthur (et al),
Just thought I'd stop by and add this latest update from the Kepler Mission manager.
Looks like it will be winter of this year before they come out with any new announcements regarding discoveries. The below quote is the first paragraph from the link.
The article talks about 200 "candidates" which have been identified for follow up. Naturally most of these candidates are likely planets with very short orbital periods.
Nothing of real note here but thought I should update the thread.
Just thought I'd stop by and add this latest update from the Kepler Mission manager.
Looks like it will be winter of this year before they come out with any new announcements regarding discoveries. The below quote is the first paragraph from the link.
QUOTE
Kepler project engineers successfully completed another download of science data over April 21-22, 2010. The data, collected since late March 2010, is the first month of the Quarter 5 collection period. During the two-day spacecraft contact, project engineers used three ground-stations in NASA’s deep space network, at Madrid, Spain, Canberra Australia, and California, for the operation.
The article talks about 200 "candidates" which have been identified for follow up. Naturally most of these candidates are likely planets with very short orbital periods.
Nothing of real note here but thought I should update the thread.
QUOTE (Quantum_Conundrum+Jan 18 2010, 03:39 AM)
Several dozen to less than 100 unique individuals, perferably inter-racial couples as they would have solved the "race" problem.
The "'race' problem" is ideological, not biological, so as long as individuals think in terms of 'races' and explain biological differences, similarities, or origins in terms of group-level distinctions, the "'race' problem" will continue in some form or other.
Nevertheless, I agree that maximum diversity among the smallest possible number of people makes sense (Noah's arc logic). Language diversity is probably also important. You would have to assemble the maximum number of distinct languages among people who are still able to communicate functionally with each other.
I wonder why people are immediately discounting gas-giants. Couldn't they have a solid core, which could be terraformed by processing whatever gas is in the atmosphere?
The "'race' problem" is ideological, not biological, so as long as individuals think in terms of 'races' and explain biological differences, similarities, or origins in terms of group-level distinctions, the "'race' problem" will continue in some form or other.
Nevertheless, I agree that maximum diversity among the smallest possible number of people makes sense (Noah's arc logic). Language diversity is probably also important. You would have to assemble the maximum number of distinct languages among people who are still able to communicate functionally with each other.
I wonder why people are immediately discounting gas-giants. Couldn't they have a solid core, which could be terraformed by processing whatever gas is in the atmosphere?
QUOTE (light in the tunnel+May 12 2010, 08:28 AM)
I wonder why people are immediately discounting gas-giants. Couldn't they have a solid core, which could be terraformed by processing whatever gas is in the atmosphere?
Well, I've never seen a description of one that was at all inviting.
If they are anything like Jupiter, then terraforming is out of the question.
http://www.usatoday.com/tech/columnist/apr...rapefruit_N.htm
Arthur
Well, I've never seen a description of one that was at all inviting.
If they are anything like Jupiter, then terraforming is out of the question.
http://www.usatoday.com/tech/columnist/apr...rapefruit_N.htm
Arthur
QUOTE (light in the tunnel+May 12 2010, 09:28 AM)
I wonder why people are immediately discounting gas-giants. Couldn't they have a solid core, which could be terraformed by processing whatever gas is in the atmosphere?
I know Adoucette already responded to this, but let me ask you a question.
How do you think it would feel to be standing on a surface of solid hydrogen surrounded by an atmosphere of liquid hydrogen? Cold? Compressed? Dead?
I know Adoucette already responded to this, but let me ask you a question.
How do you think it would feel to be standing on a surface of solid hydrogen surrounded by an atmosphere of liquid hydrogen? Cold? Compressed? Dead?
QUOTE (adoucette+May 12 2010, 01:53 PM)
Well, I've never seen a description of one that was at all inviting.
If they are anything like Jupiter, then terraforming is out of the question.
http://www.usatoday.com/tech/columnist/apr...rapefruit_N.htm
Arthur
If you wanted to terraform Europa, Jupiter could be a source of hydrogen fuel, no?
If they are anything like Jupiter, then terraforming is out of the question.
http://www.usatoday.com/tech/columnist/apr...rapefruit_N.htm
Arthur
If you wanted to terraform Europa, Jupiter could be a source of hydrogen fuel, no?
QUOTE (light in the tunnel+May 12 2010, 09:03 AM)
If you wanted to terraform Europa, Jupiter could be a source of hydrogen fuel, no?
I sincerely doubt it.
The gravitational field of Jupiter is such that you wouldn't want to have to expend the energy to get the H2 away from it.
That and the fact that Jupiter is a very unfriendly place, for humans or robots.
I suspect that if one wanted H2 one would get it from the H2O that Europa has plenty of.
That said, any thoughts of Terraforming another planet are a tad premature.
If we ever have that level of technology then any discussions we are now having about how to go about it will likely seem very silly.
Arthur
I sincerely doubt it.
The gravitational field of Jupiter is such that you wouldn't want to have to expend the energy to get the H2 away from it.
That and the fact that Jupiter is a very unfriendly place, for humans or robots.
I suspect that if one wanted H2 one would get it from the H2O that Europa has plenty of.
That said, any thoughts of Terraforming another planet are a tad premature.
If we ever have that level of technology then any discussions we are now having about how to go about it will likely seem very silly.
Arthur
QUOTE (adoucette+May 12 2010, 02:23 PM)
The gravitational field of Jupiter is such that you wouldn't want to have to expend the energy to get the H2 away from it.
If you would approach Jupiter at a significant speed anyway, would it be that difficult to establish an eliptical orbit that would make it possible to skim the upper atmosphere for H2 or whatever other gas is present?
You could also establish a space-station at an orbit very close to the atmosphere, no? How strong is the gravity at that altitude?
You could also establish a space-station at an orbit very close to the atmosphere, no? How strong is the gravity at that altitude?
I suspect that if one wanted H2 one would get it from the H2O that Europa has plenty of.
True, but Jupiter could turn out to be a convenient place for harvesting H2 fuel if tanking up doesn't require landing and re-launch.
It might be easier than finding an Earth-like planet, no?
It might be easier than finding an Earth-like planet, no?
If we ever have that level of technology then any discussions we are now having about how to go about it will likely seem very silly.
How would such technologies ever be developed if they weren't first established as realistic prospects?
You really don't see any contradiction, do you?
Earth is a small, rocky planet. Gas-giants are large, high gravity, balls of gases in various states.
How are gas-giants Earth-like?
You really don't see any contradiction, do you?
Earth is a small, rocky planet. Gas-giants are large, high gravity, balls of gases in various states.
How are gas-giants Earth-like?
If the core of the gas-giant resembles Earth, that would make the gas-giant an Earth-type planet with a giant gaseous atmosphere, wouldn't it?
If you would approach Jupiter at a significant speed anyway, would it be that difficult to establish an eliptical orbit that would make it possible to skim the upper atmosphere for H2 or whatever other gas is present?
QUOTE
That and the fact that Jupiter is a very unfriendly place, for humans or robots.
You could also establish a space-station at an orbit very close to the atmosphere, no? How strong is the gravity at that altitude?
QUOTE (->
| QUOTE |
| That and the fact that Jupiter is a very unfriendly place, for humans or robots. |
You could also establish a space-station at an orbit very close to the atmosphere, no? How strong is the gravity at that altitude?
I suspect that if one wanted H2 one would get it from the H2O that Europa has plenty of.
True, but Jupiter could turn out to be a convenient place for harvesting H2 fuel if tanking up doesn't require landing and re-launch.
QUOTE
That said, any thoughts of Terraforming another planet are a tad premature.
It might be easier than finding an Earth-like planet, no?
QUOTE (->
| QUOTE |
| That said, any thoughts of Terraforming another planet are a tad premature. |
It might be easier than finding an Earth-like planet, no?
If we ever have that level of technology then any discussions we are now having about how to go about it will likely seem very silly.
How would such technologies ever be developed if they weren't first established as realistic prospects?
QUOTE (light in the tunnel+May 12 2010, 09:40 AM)
If you would approach Jupiter at a significant speed anyway, would it be that difficult to establish an eliptical orbit that would make it possible to skim the upper atmosphere for H2 or whatever other gas is present?
You could also establish a space-station at an orbit very close to the atmosphere, no? How strong is the gravity at that altitude?
True, but Jupiter could turn out to be a convenient place for harvesting H2 fuel if tanking up doesn't require landing and re-launch.
It might be easier than finding an Earth-like planet, no?
How would such technologies ever be developed if they weren't first established as realistic prospects?
Everything is possible, doesn't make it probable though.
As far as I know, no one is contemplating colonizing Europa, so all these questions are meaningless.
Why not focus on something that we are actually contemplating, like what it would take to put an outpost on Mars?.
Oh, and quit hijacking threads, this one is about Kepler's production. If you want to discuss teraforming planets, start a thread on it.
Arthur
You could also establish a space-station at an orbit very close to the atmosphere, no? How strong is the gravity at that altitude?
True, but Jupiter could turn out to be a convenient place for harvesting H2 fuel if tanking up doesn't require landing and re-launch.
It might be easier than finding an Earth-like planet, no?
How would such technologies ever be developed if they weren't first established as realistic prospects?
Everything is possible, doesn't make it probable though.
As far as I know, no one is contemplating colonizing Europa, so all these questions are meaningless.
Why not focus on something that we are actually contemplating, like what it would take to put an outpost on Mars?.
Oh, and quit hijacking threads, this one is about Kepler's production. If you want to discuss teraforming planets, start a thread on it.
Arthur
QUOTE (adoucette+May 12 2010, 04:58 PM)
Everything is possible, doesn't make it probable though.
As far as I know, no one is contemplating colonizing Europa, so all these questions are meaningless.
Why not focus on something that we are actually contemplating, like what it would take to put an outpost on Mars?.
Oh, and quit hijacking threads, this one is about Kepler's production. If you want to discuss teraforming planets, start a thread on it.
Arthur
I didn't hijack it. I was responding to posts about the problem of finding gas-giant stars instead of rocky ones. My point was that there's no reason why any given gas-giant can't have a rocky core. I only mentioned terraforming insofar as that would be the logical reason for processing the atmosphere of a gas-giant planet to reveal the rocky center, if it had one.
As far as I know, no one is contemplating colonizing Europa, so all these questions are meaningless.
Why not focus on something that we are actually contemplating, like what it would take to put an outpost on Mars?.
Oh, and quit hijacking threads, this one is about Kepler's production. If you want to discuss teraforming planets, start a thread on it.
Arthur
I didn't hijack it. I was responding to posts about the problem of finding gas-giant stars instead of rocky ones. My point was that there's no reason why any given gas-giant can't have a rocky core. I only mentioned terraforming insofar as that would be the logical reason for processing the atmosphere of a gas-giant planet to reveal the rocky center, if it had one.
QUOTE (light in the tunnel+May 12 2010, 02:32 PM)
I didn't hijack it. I was responding to posts about the problem of finding gas-giant stars instead of rocky ones. My point was that there's no reason why any given gas-giant can't have a rocky core. I only mentioned terraforming insofar as that would be the logical reason for processing the atmosphere of a gas-giant planet to reveal the rocky center, if it had one.
The "rocky" core is probably composed of metallic hydrogen. As soon as you remove the atmosphere (which composes most of Jupiter's mass), the rocky core would simply revert to its gaseous state.
You're much better off trying to colonize one of Jupiter's moons.
The "rocky" core is probably composed of metallic hydrogen. As soon as you remove the atmosphere (which composes most of Jupiter's mass), the rocky core would simply revert to its gaseous state.
You're much better off trying to colonize one of Jupiter's moons.
QUOTE (flyingbuttressman+May 12 2010, 06:36 PM)
The "rocky" core is probably composed of metallic hydrogen. As soon as you remove the atmosphere (which composes most of Jupiter's mass), the rocky core would simply revert to its gaseous state.
You're much better off trying to colonize one of Jupiter's moons.
(sigh) I wasn't talking specifically about Jupiter, which I said in an earlier post would be a possible source of hydrogen without having to land and relaunch on Europa.
I was talking about all these other prospective planets that are expected to be gas giants instead of small rocky ones like Earth. My point was that some of those planets may be rocky terrestrial-type planets at their core, which just happen to have massive atmospheres.
In other words, you don't have to assume an either-or dichotomy between terrestrial planets and gas-giants.
You're much better off trying to colonize one of Jupiter's moons.
(sigh) I wasn't talking specifically about Jupiter, which I said in an earlier post would be a possible source of hydrogen without having to land and relaunch on Europa.
I was talking about all these other prospective planets that are expected to be gas giants instead of small rocky ones like Earth. My point was that some of those planets may be rocky terrestrial-type planets at their core, which just happen to have massive atmospheres.
In other words, you don't have to assume an either-or dichotomy between terrestrial planets and gas-giants.
QUOTE (light in the tunnel+May 12 2010, 02:46 PM)
In other words, you don't have to assume an either-or dichotomy between terrestrial planets and gas-giants.
Find some intermediates then.
Find some intermediates then.
QUOTE (flyingbuttressman+May 12 2010, 06:48 PM)
Find some intermediates then.
What, do you immediately assume that for either-or dichotomies to be challenged, things have to be classifiable according to a continuum?
I don't know what all the possible core-configurations of gas-giant planets are, but I don't see why some couldn't be comparable to the composition of Earth. How could you have an intermediary form? The atmosphere of a planet is either transparent or not. Technically wouldn't cloud-cover on Earth make it intermediate? Would we have been able to figure out that Venus was not just a ball of CO2 if no probe had been sent to investigate?
Another thing I've wondered about regarding this topic, actually, is to what extent position in solar gravity is responsible for the form of planets. Could it be that gas giants tend to form in the outer solar system as a result of reduced solar gravity there? Or do you think it's just a coincidence?
What, do you immediately assume that for either-or dichotomies to be challenged, things have to be classifiable according to a continuum?
I don't know what all the possible core-configurations of gas-giant planets are, but I don't see why some couldn't be comparable to the composition of Earth. How could you have an intermediary form? The atmosphere of a planet is either transparent or not. Technically wouldn't cloud-cover on Earth make it intermediate? Would we have been able to figure out that Venus was not just a ball of CO2 if no probe had been sent to investigate?
Another thing I've wondered about regarding this topic, actually, is to what extent position in solar gravity is responsible for the form of planets. Could it be that gas giants tend to form in the outer solar system as a result of reduced solar gravity there? Or do you think it's just a coincidence?
QUOTE (light in the tunnel+May 12 2010, 01:32 PM)
I didn't hijack it.
You did.
Nothing in your posts has anything to do with the Kepler mission.
We all go off on tangents now and again, but with you it seems to ALWAYS be about what you want to discuss, regardless of the thread topic.
Arthur
You did.
Nothing in your posts has anything to do with the Kepler mission.
We all go off on tangents now and again, but with you it seems to ALWAYS be about what you want to discuss, regardless of the thread topic.
Arthur
QUOTE (adoucette+May 12 2010, 07:07 PM)
You did.
Nothing in your posts has anything to do with the Kepler mission.
We all go off on tangents now and again, but with you it seems to ALWAYS be about what you want to discuss, regardless of the thread topic.
Arthur
The thread topic is "how many Earth-like exoplanets . . . " There was talk of gas-giants being more prevalent than Earth-like planets. My point was that some of the gas-giants could be Earth-like. What's off topic about that?
Nothing in your posts has anything to do with the Kepler mission.
We all go off on tangents now and again, but with you it seems to ALWAYS be about what you want to discuss, regardless of the thread topic.
Arthur
The thread topic is "how many Earth-like exoplanets . . . " There was talk of gas-giants being more prevalent than Earth-like planets. My point was that some of the gas-giants could be Earth-like. What's off topic about that?
QUOTE
My point was that some of the gas-giants could be Earth-like.
You really don't see any contradiction, do you?
Earth is a small, rocky planet. Gas-giants are large, high gravity, balls of gases in various states.
How are gas-giants Earth-like?
QUOTE (AlexG+May 12 2010, 07:23 PM)
You really don't see any contradiction, do you?
Earth is a small, rocky planet. Gas-giants are large, high gravity, balls of gases in various states.
How are gas-giants Earth-like?
If the core of the gas-giant resembles Earth, that would make the gas-giant an Earth-type planet with a giant gaseous atmosphere, wouldn't it?
QUOTE (light in the tunnel+May 12 2010, 04:07 PM)
If the core of the gas-giant resembles Earth, that would make the gas-giant an Earth-type planet with a giant gaseous atmosphere, wouldn't it?
You don't seem to get the fact that gas giants are different because of their elemental composition. I'm sure that Jupiter has more than 100 times the amount of silicon on Earth. The difference is that silicon is a tiny fraction of the total mass of Jupiter. Because of this, Jupiter's core is mostly composed of Hydrogen and Helium.
If you took away Hydrogen and Helium from all the planets in the Solar System, they might all be similar in relative size and composition.
What you said is akin to saying "If I took all the water out of my soda, it would be kind-of like a cheeseburger." If you took all the Hydrogen and Helium out of jupiter, you would be left with planetary sludge, not a well-formed silicon core.
You don't seem to get the fact that gas giants are different because of their elemental composition. I'm sure that Jupiter has more than 100 times the amount of silicon on Earth. The difference is that silicon is a tiny fraction of the total mass of Jupiter. Because of this, Jupiter's core is mostly composed of Hydrogen and Helium.
If you took away Hydrogen and Helium from all the planets in the Solar System, they might all be similar in relative size and composition.
What you said is akin to saying "If I took all the water out of my soda, it would be kind-of like a cheeseburger." If you took all the Hydrogen and Helium out of jupiter, you would be left with planetary sludge, not a well-formed silicon core.
QUOTE (flyingbuttressman+May 12 2010, 08:15 PM)
You don't seem to get the fact that gas giants are different because of their elemental composition. I'm sure that Jupiter has more than 100 times the amount of silicon on Earth. The difference is that silicon is a tiny fraction of the total mass of Jupiter. Because of this, Jupiter's core is mostly composed of Hydrogen and Helium.
If you took away Hydrogen and Helium from all the planets in the Solar System, they might all be similar in relative size and composition.
What you said is akin to saying "If I took all the water out of my soda, it would be kind-of like a cheeseburger." If you took all the Hydrogen and Helium out of jupiter, you would be left with planetary sludge, not a well-formed silicon core.
Does that also mean that no gas-giant planet in any solar system could have a core that resembles a terrestrial planet? If it does, then I was wrong.
If you took away Hydrogen and Helium from all the planets in the Solar System, they might all be similar in relative size and composition.
What you said is akin to saying "If I took all the water out of my soda, it would be kind-of like a cheeseburger." If you took all the Hydrogen and Helium out of jupiter, you would be left with planetary sludge, not a well-formed silicon core.
Does that also mean that no gas-giant planet in any solar system could have a core that resembles a terrestrial planet? If it does, then I was wrong.
QUOTE (light in the tunnel+May 12 2010, 04:19 PM)
Does that also mean that no gas-giant planet in any solar system could have a core that resembles a terrestrial planet? If it does, then I was wrong.
That would be my guess. You might as well ask if there are any stars that have a core that resembles a terrestrial planet.
That would be my guess. You might as well ask if there are any stars that have a core that resembles a terrestrial planet.
Here's the latest update from Kepler. This announcement covers observations from the first 43 days. That's right. Only the first 43 days. In that time, Kepler has identified 706 potential extrasolar planets.
This is the Space dot come story on Yahoo.
And here is the referenced release on the Kepler Website.
I'll continue to update this as they make announcements. Do not forget that all these candidates are yet to be confirmed by ground or other observations. Also, that "goldilocks zone" candidates will take 2 or 3 years to confirm since Kepler is using the transit method to detect them.
This is the Space dot come story on Yahoo.
And here is the referenced release on the Kepler Website.
I'll continue to update this as they make announcements. Do not forget that all these candidates are yet to be confirmed by ground or other observations. Also, that "goldilocks zone" candidates will take 2 or 3 years to confirm since Kepler is using the transit method to detect them.
QUOTE (uaafanblog+Jun 19 2010, 10:14 PM)
Here's the latest update from Kepler. This announcement covers observations from the first 43 days. That's right. Only the first 43 days. In that time, Kepler has identified 706 potential extrasolar planets.
This is the Space dot come story on Yahoo.
And here is the referenced release on the Kepler Website.
I'll continue to update this as they make announcements. Do not forget that all these candidates are yet to be confirmed by ground or other observations. Also, that "goldilocks zone" candidates will take 2 or 3 years to confirm since Kepler is using the transit method to detect them.
It would be interesting if there was a list of each potential planet with its distance and the time it would take to travel there and return under constant 1g acceleration both ways. It would also be interesting to know how many years would pass on Earth compared to how many would be experienced by the crew. I realize it would probably be several generations, but it would contextualize what it would be like to be born on a spacecraft 20 years before arriving on Earth to compare what you had learned about it with what it became. This could provide lots of fuel for mediocre sci-fi stories.
This is the Space dot come story on Yahoo.
And here is the referenced release on the Kepler Website.
I'll continue to update this as they make announcements. Do not forget that all these candidates are yet to be confirmed by ground or other observations. Also, that "goldilocks zone" candidates will take 2 or 3 years to confirm since Kepler is using the transit method to detect them.
It would be interesting if there was a list of each potential planet with its distance and the time it would take to travel there and return under constant 1g acceleration both ways. It would also be interesting to know how many years would pass on Earth compared to how many would be experienced by the crew. I realize it would probably be several generations, but it would contextualize what it would be like to be born on a spacecraft 20 years before arriving on Earth to compare what you had learned about it with what it became. This could provide lots of fuel for mediocre sci-fi stories.
QUOTE (light in the tunnel+Jun 19 2010, 04:06 PM)
It would be interesting if there was a list of each potential planet with its distance and the time it would take to travel there and return under constant 1g acceleration both ways.
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