The story of why the NASA bureaucracy failed the space shuttle Columbia is an interesting one (full CAIB report here), but I’d never heard this before:
[T]he Shuttle was specced out as NASA’s next big thing after Apollo. But Congress was cutting NASA’s budget, massively. So to keep the Shuttle, NASA had to get the USAF to buy into it. USAF needed a mission — so they decided to spec out the Shuttle payload bay as large enough to hold a Big Bird or equivalent spysat, the Shuttle launch profile as including a polar orbit option from Vandenburg AFB. This then mandated a requirement that the Shuttle be able to execute its re-entry without passing over Communist territory (i.e. Russia and China) because the Shuttle was military kit.
Upshot: it had a h-u-g-e payload bay (of little use to NASA — they only really filled it with Hubble, itself built to roughly the same specs as the NRO’s big eyes, albeit with different optics). It had to have a big airframe to hold the payload bay, and it had to re-enter quickly, over the Pacific, rather than taking half the Earth’s circumference to slow down. This increased its weight, and thus the thermal loading on the TPS. Needless to say, the USAF never actually used the Shuttle as a spysat launcher … but the design compromises really contributed to the thermal environment in which the Columbia’s wing burned through on re-entry.
