The opening paragraph of this article caught my eye*:

Three space station crew members put on spacesuits and boarded their Soyuz spacecraft Friday for a short trip to relocate the capsule to a new docking port on the orbiting outpost, clearing the way for the arrival of three new residents next week.

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It seems to indicate that three cosmonauts are required to move a Soyuz - is this true?

If so, why?

*Well, it caught Tildal's eye.

  • 9
    $\begingroup$ Two to hold the ladder, and one to.. No, wait, that's changing a light bulb. $\endgroup$
    – DJohnM
    Nov 3 '13 at 3:12

There are usually 6 crew members, and 2 Soyuz spacecraft on station. Each Soyuz carries 3 astronauts.

If there is an issue redocking during the move procedure, the backup plan is to return to earth. If they cannot redock and someone is left on the station, they would be stranded and cause all sorts of downstream issues.

So no, you do not need 3 to move a Soyuz, but because it is the ride home for 3 they need to be in it, in case they need to use it. For safety during launch and landing, each astronaut has a custom made seat liner, and they usually leave it in the Soyuz they intend to use.

This will get more interesting when they start using the commercial vendors, which are designed for 7 passengers (CST-100, DragonRider, Dream Chaser) but NASA is only planning on launching with 4 passengers (For a crew size of 7).

  • 1
    $\begingroup$ Custom made seat liners? Interesting. Any references about that for further reading? Seems odd that an average type seat form wouldn't work just as adequately. $\endgroup$
    – Carl
    Nov 5 '13 at 5:18
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    $\begingroup$ The official site of NPP Zvezda the producer of the seats (as well as space suites and many other manned exploration stuff ) has a page dedicated to the Kazbek seats. The site seems to be down temporary, so use the wayback machine copy $\endgroup$
    – horsh
    Nov 5 '13 at 7:48
  • $\begingroup$ @Carl One of the 'actions' for a crew transfer (direct as was mostly done on Mir) was to change your seat liners from the old Soyuz to the new Soyuz. $\endgroup$
    – geoffc
    Nov 5 '13 at 12:07
  • $\begingroup$ This answer should maybe point out that docking operations are always a high-risk situation. A simple pilot mistake can crash the capsule into the station and cause serious damage. That's why it is important to be able to evacuate the station immediately during a docking operation. $\endgroup$
    – Philipp
    Nov 20 '13 at 23:04
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    $\begingroup$ @ChrisR The station is only really able to supply lifesupport for 7 people for sustained time periods. When the shuttle was docked, it generated power, provided oxygen, co2 scrubbing etc, sized for the 7 people it would bring with it. If Russia delivers three by Soyuz, and the station can only handle 4 more, not much point in launching 7 then. $\endgroup$
    – geoffc
    Feb 7 '14 at 17:28

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