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According to the lists of spacewalks (1965-1999, 2000-2014), spacewalks have all consisted of only two people. The only exceptions are the very early space missions, where only one person went out, and one spacewalk on STS-49 which had 3 people. It makes sense that you would want more than one person to go out, in case something happens to one of them, and you would still want people inside in case something goes wrong.

Is there a written protocol for spacewalks which determines how many people must go out and how many must stay inside? Or do the various space agencies just play it by ear and try to minimize the number of people who go out?

Phiteros
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  • Airlock capacity will be a limiting factor. In an emergency, you don't want people to have to wait outside for the airlock to cycle. – Hobbes Mar 14 '17 at 07:11

1 Answers1

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"Is there a written protocol for spacewalks which determines how many people must go out and how many must stay inside? "

There was for Shuttle. It's in the book that laid down the law for shuttle operations, the Flight Rules. (Warning, giant pdf)

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Organic Marble
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  • Very interesting. Does there happen to be a similar document available for the ISS? – Phiteros Mar 13 '17 at 22:45
  • There is a flight rules book for ISS, but I've never seen it posted online. The shuttle rules only got posted because of the Columbia accident. – Organic Marble Mar 13 '17 at 22:52
  • Hm, you'd think that there wouldn't be a strong reason for something like that to be kept confidential. Your answer is very good, but I think I'm going to keep it open for a few days to see if anyone else has something more recent to add. – Phiteros Mar 13 '17 at 23:47
  • It made no sense to me either. There used to be a warning in the shuttle book something like "Posting this document on any public electronic forum is expressly forbidden" – Organic Marble Mar 14 '17 at 00:03
  • @OrganicMarble I can imagine there might be one or two extreme-case rules that someone decided should not see the light of day, and faced with the notion of splitting it into a big public plus a small secret rule book, they just decided not to. Things like nuclear war, space-murder, astro-cannibalism if there is no supply ship, etc. – uhoh Mar 14 '17 at 04:00
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    The nuclear war rule is in the linked document, it's rule A14-1. The classified missions had a separate volume for the classified rules. – Organic Marble Mar 14 '17 at 04:02
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    The launch will be held if the nuclear war happens prior to T-31 seconds. Otherwise the count will proceed. (Rule A14-1001 note [2]) – Organic Marble Mar 14 '17 at 04:04
  • Do the flight rules actually explicitly say "Self-explanatory"? (Page 2-120, point C.) – user Mar 14 '17 at 10:10
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    @MichaelKjörling I didn't find that page, but yeah, the rules contain rationale in italics. If the writer did not think an actual rationale explanation was necessary, you will see that notation. – Organic Marble Mar 14 '17 at 12:58
  • It's about half way down on the middle page included in your answer. – user Mar 14 '17 at 13:09
  • Since ISS is usually crewed with 3 people and one must stay on board, 2 people on EVA is the usual maximum. During crew exchange, while 6 people are on board, they could utilize all EVA suits (2 NASA and 2 Orlan) for a 4-person EVA, but they usually have far more urgent work on hands, and no reasons for such an EVA. – SF. Mar 14 '17 at 13:20
  • The normal ISS crew complement is 6. http://www.howmanypeopleareinspacerightnow.com/ – Organic Marble Mar 14 '17 at 13:22