NASA suggests crew was doomed at shuttle’s liftoff
By Martin Merzer, Phil Long and Sumana Chatterjee ,
Knight Ridder Newspapers
02/03/2003 10:30 PM
That piece of foam that fell off and struck the wing is currently the most likely culprit for the shuttle disaster.
I suppose this is a silly question, but if I don’t ask, I won’t know. Does the shuttle (or any space bound craft) experience similar friction on the way out of our atmoshpere as it does on the way back in? (I’m guessing not) Why or why not? Aren’t the velocities similar?
Good question actually. I expect someone will corect me on the details but I don’t think the velocity profile is the same going up as it is coming down. They may be higher at the same velocity on the return path. Also the atmophere is thinning during the trip rather than getting heavier. When they are returning they are at nearly full velocity until the atmosphere begins to slow them. They are also in a high angle of attack that has high drag. This helps convert the kinetic energy of the shuttle into thermal energy.
When the shuttle comes down through the atmosphere the velocity is very high and it meets thicker and thicker air which builds up the friction slowing it down at the same time as the heat builds up. When lifting from ground it starts from sea level, where the air is thickest, with zero velocity. As the speed builds up the air gets thinner and thinner, so the friction against the air gets less and less.