This article on testing satellite shielding against space debris is a good reminder that even if NASA solves the foam problem, or someone comes up with a new reusable vehicle concept that isn’t subject to debris during ascent, that space vehicles will always be vulnerable to orbital debris:

An object less than 0.05 inch across blew a hole through a section near the payload door of the shuttle Atlantis during its mission last September, according to the July edition of NASA’s Orbital Debris Quarterly News journal.

The damaged section was replaced.

Had the object, which investigators think was a piece of a circuit board, hit the thinnest part of the wing edge, “There is a question whether the vehicle would have survived re-entry,” said Eric Christiansen, a NASA engineer specializing in debris shielding.

A spacefaring nation will have the capability to do repairs on orbit to mitigate the hazard of such events, but to do that requires the development of a orbital infrastructure, something that NASA’s current plans strenuously avoid.