Notes and Reflections on Books and Media
by Hannah Leitheiser
Accessory to War: The Unspoken Alliance Between Astrophysics and the Military
Neil deGrasse Tyson
"As an...officer saw fit to inform him...'The Hubble was a Keyhole Class Satellite, not the other way around.'" - Neil deGrasse Tyson, Accessory to War: The Unspoken Alliance Between Astrophysics and the Military (2018SEP)
Twenty Keyhole spy satellites were launched starting in 1971. Hubble launched in 1990. Temperature related shuttering of metal was a known issue but couldn't be discussed with the Hubble crew.
BTW, a little back-of-the-envelope math: if you turn Hubble to earth, 13 cm (max) resolution. Used to think without Adaptive Optics, earth objects would twinkle like stars, limiting resolution, but exposure times are fast enough to overcome the problem.