From Fallout 3, we learned there had been manned moon missions until the mid-21st century, and in the Van Buren design docs (as questionably canon as they might be), there were plans for Mars missions. There was also some kind of work to flee nuclear apocalypse by launching an ark spacecraft by the Enclave, though we'll likely never know how far along that was, just that Project Safehouse was part of the experimenting in that.
So my question is, just how much of a space presence was there before the world ended? Maybe there were survivors on the Moon, before the lack of supplies did them in? Maybe a pre-War variant of the ISS is floating up there, full of corpses? Maybe the B.O.M.B.-001 is up there, waiting for a guy like Presper to set it off?