The foam strike was confirmed through video analysis. I myself saw the foam chunk break off the external tank and strike the leading edge of the left leading edge RCC on the wing. If you actually read the Columbia Accident Investigation Board's report, the evidence for the foam strike causing the hole which destroyed the shuttle on re-entry... the evidence is absolutely overwhelming.
Yes, I've seen the same video too. You see a piece of foam come off the tank and clearly strike the wing. There is also footage of nasa doing tests on a wing section with dramatic damage done to the wing. When I saw the video of the launch I noticed something about the impact. The foam chunk seemed to turn to powder after striking the wing.
This suggests that the blow was not a direct one. But, was in fact offset above center of the wing. Also the fact that it was deflected and reduced to powder suggests that a great deal of the energy was diffused in the reaction.
The fact is that something bad happened during re-entry and the problem obviously started in the left wing. I think that the damage to the tiles was not as severe as previously thought but was enough to doom the craft.
As we know the tiles are made of a material similar to glass, and provides a great insulator to heat, and would in fact prove a great insulator to electrical discharge.
I think it's perfectly feesible to think that the damage damaged the insulation enough to allow the plasma to get to the internal members but not been comprimised to the point of total failure. Evidence during re-entry shows increasing temperatures in the left wing region of the craft. But it wasnt rapid.
I think this suggests that the "leak" wasnt very large at the beginning of the incident. Though the closing of the circuit between the plasma and internal members as well as the ion trail was enough to induce a discharge.
The damage would have been massive. The temperature of the strike would have far excessed the 3000 degrees of normal re-entry and the evident spark erosion on tiles found would have worsened the already damaged tiles. As well as the sudden cut-out of communications and of the documentry video on board, shows power failure.
It maybe that the craft would have been lost anyway, but i think explaining it as outright tile failure, and something we have control of and can fix, is far more soothing to the American public then atmospheric phenomina we know little to nothing about.
The leading edge of the wings on the shuttle are not made from the silicon glass tiles, they are made from a carbon-carbon composit material, which is more brittle but can take a higher temperature then the tiles. That is what was damaged by the foam strike not tiles. Airplanes are struck by lightning all the time. Most of the time the damage is minimal (holes burned in the skin, electrical components burned out). Sometimes the damage can be catastrophic, but that is very rare.
Krreagan
infohound
20th February 2006 - 04:00 AM
NASA's testing showed that a foam strike CAN cause damage severe enough to compromise shuttle integrity, but this IS NOT hard evidence that foam strike(s) caused the destruction of Columbia.
In the National Geographic video documentary titled MEGA LIGHTNING, in which the purple streak photo is featured, Dr Umran Inan, of Stanford University, heading NASA's "lightning hunters" states that there was NO ELECTRICAL ACTIVITY in the area of Columbia's descent.
Re the "purple streak": there is no substitute for seeing the photo; perhaps that's why the the documentary is so mysteriously unavaliable. The streak emerges from black sky far above Columbia, corksrcews 3 revolutions then makes a straight track toward Columbia, passes behind it and makes an instant RIGHT-ANGLE course correction, again corkscrews 3 revoluions and again streaks straight toward Columbia, making contact at the exact time that NASA's telemetry showed a big spike in temperature readings and contact with Columbia was lost; 6 minutes before Columbia broke up.
Is this the behavior of a natural phenomenon?
It IS the behavior of a self-guided weapon. As I said, there's no substitute for seeing the photo, but the above description of it is accurate. And no, I'm not implying that it was some kind of alien attack. Draw your own conclusions.
Ixion
22nd February 2006 - 04:46 AM
Thank you for the correction on the material composition.
Mega-lightning isnt the same kind of lightning that you see coming out of clouds and striking the ground. It's positively charged and at much greater voltage as well as much hotter. Unlike negative cloud lightning which discharges multiple times, mega-lightning disharges all at once. As I said it would have been much like a cutting torch... burning a path to the nearest metallic internal member. My guess would be inward since the plasma jet seemed to be directed at the wheel well. Where temperature readings began spiking.
Vast majority of lower atmosphere lightning is negative. The catastrophic damage could be attributed to the much rarer mega-lightning strikes.
They are two different beasts.
Unfortunatly whatever the case may be the crew was probably doomed. Space travel is dangerous.
However, the possibility alone demands study. There is a whole electrical system in our atmosphere we know little about, and with talk of space elevators there are many questions that still need to be answered.