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ARtone
Hi all check this for unusual

http://www.rednova.com/news/stories/1/2004...7/story003.html

Anyone want to offer and explanation of this effect small download video on the site showing what happened when the solder was heated in space.

AR
Neutron
I'm sure there is a simple explanation like air blowing from air conditioner (or what they use on the station for air circulation), etc.
dirak
Yes, I agree with Neuton.
It is very clear from that movie: (a) the smoke goes away, so there is some airflow; (b ) the soldering iron is not fixed, the hand is shaking a bit. So, I nether been in space biggrin.gif, but I believe in weightless enviroment such thing can cause that effect.
ARtone
Hi

They use a device to prevent floating spillage which draws of anything floating hence the sideways smoke. But you will see if you download one of the clips that the rotational speed increases as the temperature does.

This would not be consistant with such an explanation.

I wouldnt minimse this effect one of their top people was amazed.

I would also think that such an explanation would have the resin floating away. There is clearly some effect holding the resin to the solder and making it spin.

AR
Neutron
QUOTE (ARtone+Sep 15 2004, 05:10 PM)
They use a device to prevent floating spillage which draws of anything floating hence the sideways smoke. But you will see if you download one of the clips that the rotational speed increases as the temperature does.

It's still consistent with my explanation.

When temperature is low, resin just sticks to the soldering iron. The higher temperature is, the lower sticking force becomes, which makes it easer to move.
z
HI All,

I would tend to agree with AR until more information is forthcoming. Air circulation might tend to cause motion, but the air circulation pattern would have to be just right to cause the circular rotation. The probability of this seems rather low, but it is possible.

Other possibilities for causality are a gravitational interaction between the solder and the resin, or some type of coriolis force.

z
Neutron
QUOTE (z+Sep 15 2004, 07:03 PM)
Other possibilities for causality are a gravitational interaction between the solder and the resin, or some type of coriolis force.

Gravitational interactions would never cause rotation. Besides in this case they are TOO small. The Corilis force is an inertial force, acting to the right of the direction of body motion for counterclockwise rotation of the reference frame or to the left for clockwise rotation, so it is also not applicable in this situation.
z
Hi Neutron,

Although it may not be applicable to this situation due to magnitude, gravitational forces are implicit in the rotation of the earth and other planits about the sun. No gravity, no rotation.

The same for coriolis forces. They may be too small to make a difference, however the space station is a rotating reference frame, so coriolis forces exist.

z
ARtone
Hi all

Surely we have a situation here simular to any satalite around a body there is some force holding the solder to the surface otherwise in no gravity it would have been thrown off in a straight line.

Also notice the the orbit path changes. It is obvious that the heat is causing the rotation as it speeds up and slows down as the wire is heated.

Remember theres no gravity and theres a slight pull to the left by the collection device.

AR
ARtone
Hi all
as resin vapour is emitted when in normal use it is possible that the resin is emmited via small holes thus providing a driving force. which could explain the heat/speed relationship

why is the orbit path changing? this could be explained by escaping gas

I would have liked to see the exp run longer as all the fluids would have eventually be driven off.

AR

Weary_scientist
My explanation is this:
First the solder heats up, and due to surface tension it draws itself into a ball. Next through slight movement, either from air or a from the hand of the astronaut there is a slight movement of the ball of rosin. There is no convection in a microgravity environment, so the rosin starts to vapourize at the hottest part. The hottest part is the area which has been in contact with the soldering iron the longest. Since there is slight movement in the solder already there will be a leading edge which has just contacted the soldering iron and a trailing edge which has been in contact with the soldering iron the longest. Since the trailing edge is the hottest it will vapourize and give the ball of rosin a small amount of thrust. It would look like burning a tire on pavement, the tire surface rubs over the ground but only smokes when it has nearly left the ground.

That's my best guess anyway,
dtwiddy@uoguelph.ca
heat'
Yes - I've seen this before. However, it didn't require the environment of a space station. Many years ago, as an intern, I had to tin the leads of a couple hundred leaded resistors. I dipped the leads of the resistors into a dish of liquid rosin flux and then poked the leads into a crucible of molten solder. The rosin sizzled and rolled up into little spheres which then whizzed across the surface of the solder. The paths of the spheres varied - some would dart across the solder and bounce off the walls of the solder-pot while others spun around in circles or spirals. Needless to say - the experimental set-up is pretty easy if one actually wants to experiment and truly figure out the underlying mechanisms. And you don't even need to be an astronaut.
ARtone
Hi weary

I dont agree that convection has anyting to do with gravity also if you download the longer clip it can be clarly seen that the resin speeds up as it gets hotter indicating that the amount of heat is important.

hi heat

I will try that experiment later.

AR

Guest_carl
QUOTE (ARtone+Sep 18 2004, 01:36 AM)
Hi weary

I dont agree that convection has anyting to do with gravity

AR: please define "convection" without referring to gravity.

weary scientist hit the nail on the head, nothing more needs to be said.
colby
Somebody needs to try and repro this effect on a vomet comet. Also, it would be nice to have the experiment tried with a fixed soldering iron.


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