[Investment Biker]

The one thing I do not understand about all this is that there must have been estimates of the RELATIVE velocity of the foam with respect to the shuttle. These estimates could be formed from the timing on the videos that show the impact. But the relative velocity is never discussed in any of these articles. Do you or anyone else have the information?

[Procyon]

From www.space.com:

81 seconds into the flight, a 20-inch, 2 1/2-pound piece of the foam fell off and struck Columbia's left wing. The shuttle Columbia was moving more than at twice the speed of sound. The impact is thought to have involved a relative speed of no more than 500 mph.

I'd have to research more to determine the airspeed 81 seconds into flight, but the relative speed was about 500 mph -- so the tests are on spot.

[Sloth]

I find it hard to believe that the foam slowed down enough to go from a delta-V of zero to 500 MPH in the short distance involved. Then again, it's hard to say without knowing the air density, shape of the chunk, and so forth.

[Atchafalaya]

I seem to remember very early after the disaster that a relative velocity of something like 80 mph was mentioned. I don't know for sure if that is true, but I seem to recall that was what the engineers were tossing out.

[eno_]

I recall a Freeper making an estimate it was around 500mph relative velocity, based on frame-rate of the high speed film.