Since in the wake of the failure of Soyuz MS-10, "humanity is effectively trapped on Earth" (this of course ignores Chinese launchers), one might try to fly one of the remaining Space Shuttle orbiters again. How hard would it be to get them into space and safely back again (assuming they don't have to be man-rated against current criteria)?
I see some problems:
- The orbiters are all in some kind of museum, but important parts (e.g. computers, engines) may have been removed or modified for display, so they might need replacement. And the orbiters probably need at least a C check.
- One would need a new external tank, since I don't think one is in storage. I somehow doubt that tools, etc. needed were safely stored away.
- The boosters might be the easiest part since SLS uses improved versions.
- The infrastructure at Cape Canaveral (Orbiter Processing Facility, Vehicle Assembly Building, Mobile Launcher Platform, Launch Pads, ...) would need to be adapted.
- The Shuttle Carriers have been retired; maybe N905NA could fly again.
- Astronauts and ground crews would need to be trained.
So how many years would it be before e.g. Atlantis would fly again?