The Dragon v2 has 7 seats whereas the Soyuz only has 3. But the Soyuz uses all 3 seats for astronauts/cosmonauts to bring to the ISS.

I suspect that Dragon v2 will bring 3-4 people to the ISS in one go but would it ever be seated with 7 people and brought up to the station? If yes, what would be the reason? And wouldn't the ISS then be too crowded?

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    $\begingroup$ I think it will get quite a bit cheaper to go to ISS as a tourist once Dragon V2 starts to make regular trips $\endgroup$
    – neelsg
    Aug 7 '15 at 14:01
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    $\begingroup$ @neelsg, Dennis Tito is I believe the only tourist to visit ISS, and NASA was not happy about it. The Russians let him come, over NASA's strong objections. NASA would not let him in American capsules without escort, if I'm not mistaken, so he was otherwise limited to Russian portions of the station. I know I'm probably taking your comment too seriously though. Dragon v2 could definitely bring down the cost of space tourism in general! $\endgroup$
    – Dan
    Aug 7 '15 at 17:52
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    $\begingroup$ @Dan: In fact, per Wikipedia there were 7 tourists who visited the ISS, one visiting twice: en.wikipedia.org/wiki/… $\endgroup$
    – jamesqf
    Aug 7 '15 at 23:46
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    $\begingroup$ @jamesqf Looks like you're quite right. I still get the impression that NASA is not enthusiastic about it though. They must have loosened up a little, but notice that all 7 went via the Russians, and the page you linked mentions that the Russkies aren't planning on sending anyone else up as a tourist for the foreseeable future. I wouldn't be surprised if they change that tune for more foreign currency though, given their economic situation. $\endgroup$
    – Dan
    Aug 8 '15 at 0:25
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    $\begingroup$ @Dan: Do we really need the offensive epithet "Russkies" on an international website? Or, for that matter, at all? Also, by that economic logic NASA would be begging for tourists too. $\endgroup$ Aug 8 '15 at 13:31

NASA has only contracted for flights with 4 astronauts, since the complement of the station is a maximum of 7 in the long term. The limit of 7 has many reasons, but some are for sleeping accommodations and life support systems capacity.

Soyuz can carry 3. Thus the current complement of ISS is limited to 6 (two Soyuz craft) at the moment.

Bringing 7 to the station would work in one flight of Dragon (or CST-100), if there were no Soyuz on station, but that is not a planned configuration. Could it happen? Sure. Anything could happen, but that is not the plan as currently set.

One possible case would be the direct hand-off. Lately, Soyuz flights have been doing indirect hand-off between missions. That is, a crew of 6 sends three home in a Soyuz, a week or three later another Soyuz launches with 3 more crew. On Mir, they would sometimes do it that way, but sometimes do it as a direct hand-off, where the new crew would launch on a Soyuz, the previous crew of 3 would be there, they would share the station for a few days to a week, then the old crew would depart. Sometimes they would change out the Soyuz, and the new Soyuz crew would leave on the old Soyuz to keep the on-station Sotyuz within its usage date. (Soyuz's in-space lifespan is 280-odd days.)

As a consequence, when shifting only 2 of the 3 crew members, there was room for a tourist.

With commercial crew (Dragon V2 or CST-100) there are more options.

With the current plan of 2 long-term stay (1 year) astronauts there are seats available for tourists on rotation flights.


When the space shuttle was in operation, it could carry as many as seven extra people, bringing the total population of the ISS up to ten. Three crew members is the standard permanent capacity of the space station, but the ISS can actually hold more. Ten is the working limit.

In practice, the maximum number of people the shuttle carried was eight, and that was on a return trip from Mir.

Given that the shuttle only once carried greater than seven crew members, the seven person capacity of the Dragon v2 makes sense.


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    $\begingroup$ But IIRC 10 wasn't the station population, but station + Shuttle. That is, some people were using the Shuttle for life support, sleeping space, &c. It's like if your out-of-town relatives come visit you for a week, and sleep in their RV parked in your driveway :-) $\endgroup$
    – jamesqf
    Aug 7 '15 at 17:51
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    $\begingroup$ @jamesqf According to my NASA source: "so there's either three, five or ten people on the station." They may not have ever actually done it this way in practice, but it was sort of designed for the capacity. Technically the space station only has two sleeping spaces but: "If it's okay with the commander, the astronaut can sleep anywhere in the space station so long as they attach themselves to something." (Ref) $\endgroup$
    – called2voyage
    Aug 7 '15 at 18:35
  • $\begingroup$ "Three crew members is the standard permanent capacity of the space station" ??? When six crewmembers stay there for six months? $\endgroup$ Aug 8 '15 at 16:32
  • $\begingroup$ @OrganicMarble Yes, notice that before Expedition 16 the standard was a three person crew: link $\endgroup$
    – called2voyage
    Aug 8 '15 at 19:40

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