I read the story (along with photos) of the test done on the replica of shuttle wing that they feel puts to rest the question of what happened to Columbia.
What I don’t understand is why they fired the foam at the wing at 500 MPH? The damage was worse than one might expect considering it was foam vs. a carbon reinforced wing but at 500 MPH I’d expect some damage. I would think that the foam, riding along with the shuttle (thus moving at the same speed as the shuttle) would in no way have enough time to accelerate to 500 MPH from breaking off to hitting the wing (a matter of a few tens of feet?).
I trust the NASA engineers know what they are doing and it’s me that is missing something…I’m just curious what that something is.
[sub]I find it strange that the Columbia was doomed just over a minute into its flight yet the disaster took place days later. I understand the hows and whys of it…just seems strange is all.[/sub]
The shuttle was moving upwards at about 2000 mph when the foam broke off. (I think that’s what I read.)
The foam, at separation time, was also moving upward at 2000 mph, but began rapid deceleration.
The difference in their velocities was the 500 mph impact, I suspect. It had *slown down a lot in that short distance because of a) no longer having an engine powering it, and b) being foam, it was big and poofy, and had a lot of drag.
Plus, knowing the dimensions of everything in the video made it easy to calculate the velocity of the foam relative to the shuttle wing. Which is exactly how they determined the test velocity to use.
Even in the now notorious 21st January Boeing report that minimised the risk during the flight, the initial assessment of the impact velocity was roughly 700 ft/s, which equates to roughly 500 mile/hr. This has since been much refined from all the additional video analysis; I presume there’s a summary of this somewhere on the STS-107 Investigation Reference Page, though I can’t quite see where.
I guess it is just amazing to me that a piece of foam could accelerate (or deccelerate as it were) to 500 MPH in the space of several feet. I’m not saying it didn’t happen…clearly it did…it just boggles the mind a bit. It was pretty stunning what that foam did to the wing replica!
Well, foam has a pretty low terminal velocity, so it’s not all that surprising. What I found surprising was the damage a piece of foam could do. I remember when the media was focusing on the video of the foam breaking off and hitting the wing, thinking “It’s foam. How much damage could it do to the space shuttle??” I was sure there was more to it than that, but no. The foam did it.
I thought the same thing briefly, then they mentioned that it was a substantial piece (I don’t remember the exact weight - 10 pounds?) of foam and the speed of impact being as high as it was…
Then I though about what it would feel like if someone threw a 10 pound chunk of styrofoam at me from a fast-moving vehicle and realized it would probably hospitalize me. Suddenly the foam theory made a lot more sense.