I'd want some LOX or LH to really find out if the foam's compressibility is affected by extreme cold. Liquid nitrogen is more easily obtainable (and safer) but might not be cold enough to prove my hypothesis.

While my gut reaction is that the foam would become quite hard at cyrogenic temperatures, there's no substitute for actual data. It could be a lot more complicated than a simple dunk test, though. The Shuttle was going about Mach 2 when the foam fell off. There's the possibility that aerodynamic heating might've warmed one side of the foam. Still, superchilling some identical foam and performing compressibility tests seems like a reasonable thing to do.

I sent the following letter to the man behind InstaPundit. He's active in the space community and may be able to get the idea out. I thought of sending it to NASA but they're probably being overwhelmed by messages, theories, and such at the moment.

Thaw the Chicken



There's an urban legend/joke about a chicken cannon used to test aircraft cockpit windshields. The joke goes that another country saw one demonstrated and was so impressed; they went back and built one of their own. However, every time they fired it, it went right through the cockpit glass. When they asked for help, the reply was "thaw the chicken."

I can't help but wonder if the NASA engineers modeling the foam impact on the wing are doing the exact opposite. According to diagrams I've seen, the foam was attached to the External Tank either near the top of the liquid hydrogen tank or near the bottom of the liquid oxygen tank. Those cryogenic propellants are hundreds of degrees below zero. Have they taken into account the effects of the cold on the foam? I'm willing to bet that super cold foam would be hard as a rock. That would affect the dynamics of the collision between the foam and the tiles considerably. Instead of being a soft and fragile piece of foam that would shatter on impact, we could have a 2.5-pound projectile. Have they frozen the chicken?

Do you remember the hearings during the Challenger investigation when the late great physicist Richard Feynman illustrated his point about how cold affects rubber using ice water? Have we forgotten his lesson that day about how temperature affects the properties of materials? I hope not.

Larry Jacks
Colorado Springs
SSAIO