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Prompted by Scott Manley's recent video on escape vehicles I wondered:

Has there ever been a moment where someone was on board a space station but without access to a vehicle that could return them back to earth?

Maybe I should also think about what I'd even consider a "Space station": I'd consider any spacecraft/vessel where the occupants used a different vehicle to get there/return. This would technically also include the lunar modules, but I'm interested in all examples you can think of!

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    $\begingroup$ @OrganicMarble No, the question you linked is exclusively about the ISS, but I'm asking a more general question that includes all space stations. $\endgroup$
    – flawr
    Commented Dec 1, 2021 at 20:44
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    $\begingroup$ Ok, for future answerers, the ISS is covered here: space.stackexchange.com/q/27793/6944 The answer for other space stations is "yes" (question in the title of your post) "no" (question in the body of your post) but I won't be writing that answer. Because space agencies are not crazy, at least not in that regard. $\endgroup$ Commented Dec 1, 2021 at 20:45
  • $\begingroup$ Related: youtube.com/watch?v=82YHM12n2JI $\endgroup$
    – Criggie
    Commented Dec 3, 2021 at 0:52

2 Answers 2

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Yes, all human occupied space stations to date have had a return vehicle for every crew member.

To my knowledge (and general consensus), that includes Skylab, Salyut, Mir, Almaz and China's Tiangong.

For the ISS there was talk of a dedicated return vehicle (Crew Return Vehicle (or Assured Return Vehicle)) that would mean the Shuttle could drop off crew, who could rely on the ARV for emergency return if needed. But it was dropped and never happened. But even then, they would have a return seat, just not on the vehicle they launched on.

Otherwise, every occupant on any of the space stations had a seat to return in at all times.

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    $\begingroup$ Additionally, if a return-vehicle had to be moved and re-docked elsewhere, the crew scheduled to return on that would have to board it for the re-arranging maneuver. (recent scott manley mentioned in youtube.com/watch?v=82YHM12n2JI ) $\endgroup$
    – Criggie
    Commented Dec 3, 2021 at 0:52
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    $\begingroup$ Although spacewalkers could be in a decidedly dodgy situation if an on-station emergency- fire or impact- developed. $\endgroup$ Commented Dec 3, 2021 at 19:20
  • $\begingroup$ @MarkMorganLloyd now you're thinking like a spaceflight training instructor! $\endgroup$ Commented Dec 4, 2021 at 0:05
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As it happens, yes, but it wasn't always considered a necessity -- the Skylab and Freedom mission rules were "happy" that another return vehicle could be launched to bring them back at the end of the mission. Skylab never got as far as that, and ISS didn't have the capacity for to support more than a Soyuz worth of crew while that policy was in place. The premise was found wanting following the lengthy return-to-flight following the Challenger failure.

Following Columbia, Orbiters were no longer considered to be guaranteed to be capable of returning their crew, so the Contingency Shuttle Crew Support missions were devised, whereby a stand-by STS had to be ready for launch within 64 days of an ISS mission launch (14 days for the original mission, 10 days for a decision to launch and 40 days to prepare)

In the event of the final shuttle mission to the ISS not being able to return its crew there would not have been enough on orbit return capacity, and the Soyuz missions would have operated on a two up three down basis at their normal cadence until the capability was restored.

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    $\begingroup$ Do you have a reference for this: "Following Columbia, Orbiters were no longer considered to be guaranteed to be capable of returning their crew, so a stand-by STS had to be ready for launch for the duration of a STS mission to the ISS"? Are you talking about the STS-4XX rescue missions? Because if you mean an STS stack was sitting on the pad ready to launch the whole time...no. $\endgroup$ Commented Dec 2, 2021 at 3:04
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    $\begingroup$ @OrganicMarble the STS-3XX missions, and while the LON missions didn't have to be ready to launch, had to be ready to be ready to launch within the 80 day window and were often stacked ready to launch $\endgroup$
    – user44124
    Commented Dec 2, 2021 at 3:31
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    $\begingroup$ @OrganicMarble better? $\endgroup$
    – user44124
    Commented Dec 2, 2021 at 4:05
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    $\begingroup$ my failing memory did merge the STS-4xx "can't reach ISS had to be stacked" missions (Hubble) with the 64 day STS-3xx "ISS or could reach ISS" missions; so thanks for pointing it out. The 80 day window is the time the ISS LSS could support the additional crew. (not enough priv to upvote your comments) $\endgroup$
    – user44124
    Commented Dec 2, 2021 at 4:13
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    $\begingroup$ Edit looks great! Welcome to space stack exchange. $\endgroup$ Commented Dec 2, 2021 at 14:15

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