Last month, six astronauts convened at the Intrepid Sea, Air & Space Museum in New York City to discuss the 2009 mission to service the Hubble Space Telescope. As it approached its 20th birthday, the telescope was in desperate need of an upgrade; the orbital optics, batteries, and other equipment had slowly deteriorated due to sun exposure and age.

NASA deployed Space Shuttle mission STS-125, the last Hubble servicing mission, to renovate the telescope in a series of space walks. "For a lot of missions, they say don't worry about things, we can always get that done next time, you don't have to try and rush," Scott Altman, the former mission commander, tells Popular Science. "But we knew this was the last time anyone was going, so anything we didn't get done, wasn't going to get done."