However, if the jetpack's of fuel runs out, and if there is no other astronaut in close proximity to help, or if the air lock is irreparably damaged, the outcome would certainly be fatal. At this time, there is no spacecraft to save an astronaut floating in space, as the only one with a rescue-ready air-locked compartment — the Space Shuttle — retired years ago. There is approximately a litre of water available via straw in an astronaut's helmet. The astronaut would wait roughly 7.5 hours for breathable air to run out before dying of suffocation.