ISS question regarding soyuz

[Umlüx]

so, those soyuz spacecraft are practically lifeboats for the crew, right? do they just stay docked up there or are they rotated somehow with the expeditions?

[Lukaszenko]

Well they have bring back crew just as much as they have to bring them up there.

Plus I hear they have a 6-month or so shelf-life due to their fuel deteriorating.

[sgt_flyer]

A soyuz TMA-M spacecraft is designed to be able to remain docked to ISS for 6 months.

When a part of the iss crew comes back to earth, they take the oldest of the soyuz to get back to earth (usually the one they came with) , and the new crew members coming to replace the departing ones comes with a new one.

(Basically, iss crews usually rotate 3 by 3 (unless there's a space tourist) and a soyuz stays for two rotations. (Crew rotation are of course staggered )

Anyway, there's always enough soyuz spacecraft docked to iss to bring back everyone on board in case of emergency (if there 's up to 3 people on board, they have 1 soyuz - 3 to 6 - two soyuz)

[Streetwind]

People have speculated about possibly increasing the amount of people on the station once a commercial crew vehicle becomes available. Something like the Dragon V2 can carry seven people, so it would be able to be a lifeboat for as many. Unless, of course, it cannot stay up there for that amount of time, but well... no info is available on that so far.

The need to have lifeboats and the limitations of available spacecraft to fill this need are actually what limits the number of people on the station. Its life support can handle more than six, and there are enough sleeping quarters too. There are proposals to increase the permanent crew size to at least seven, maybe more, once a larger capacity vehicle becomes available to replace one of the two Soyuz on lifeboat duty. As it is, the astronauts on the ISS work 65-hour weeks and would very much welcome additional manpower. Not to mention that there's room for more science experiments too, provided you could find someone with time in their schedule to do them...

[Umlüx]

thanks. especially sgt_flyer, exactly the answer i was looking for.

[Sky_walker]

People have speculated about possibly increasing the amount of people on the station once a commercial crew vehicle becomes available. Something like the Dragon V2 can carry seven people, so it would be able to be a lifeboat for as many.

That won't happen, not when ATV is retired.

Ability to bring more people up and down from ISS isn't a deciding factor to the amount of crew onboard. Ability to bring life support and experiments (work) for them is.

Not to mention that there's room for more science experiments too

None of the commercial resupply vessels come close to the capabilities of ATV or H-II.

[Kryten]

They do plan to increase crew size, but only by one.

[Nibb31]

Note that everyone who flies on Soyuz has their own personal thermoformed seat cushion adapted to their morphology. So when they rotate the Soyuz, the crew needs to transfer their cushion to the spacecraft they will be travelling down in.

[Streetwind]

That won't happen, not when ATV is retired.

(...)

None of the commercial resupply vessels come close to the capabilities of ATV or H-II.

The ATV flew what, five times in seven years? And even with 7 tons of useful payload in the recent flight, that's less total than what Dragon alone will bring to the ISS this year, not counting Cygnus, Progress and H-II. And considering it's getting retired simply because the other options are cheaper per kg, they clearly have an idea of how to keep up the supply chain using those other options. I wouldn't worry so much about it.

They do plan to increase crew size, but only by one.

Are they actually commited to that now? That would be awesome.

[dharak1]

An increase of crew to 7? Would that make a new record for number of people in orbit at once? That is the current record? It must be something like 14 from when the shuttle flew right? I don't know but anything that slightly increases my chances to get on a spacecraft

[Streetwind]

IIRC the record was 13 during a shuttle docking, yes. Six on the ISS and seven on the shuttle. The shuttle's life support systems helped the station, though, and it was only for a couple days.

[Sky_walker]

An increase of crew to 7? Would that make a new record for number of people in orbit at once?

Not even close

[Mr Shifty]

IIRC the record was 13 during a shuttle docking, yes. Six on the ISS and seven on the shuttle. The shuttle's life support systems helped the station, though, and it was only for a couple days.

I believe there were 13 people on orbit in the same spacecraft during STS-127/Expedition 20, STS-128/Expedition 20, and STS-131/Expedition 23. STS-127 was on-orbit for 15 days, 16 hours and was docked to the ISS for nearly 11 days.

The first time 13 people were on orbit was during the launch of Souyz TM-21 to Mir in 1995. There were 7 astronauts on board Endeavour for STS-67 (the Astro-2 Spacelab mission), 1 astronaut and 2 cosmonauts on-board Soyuz TM-21 bound for Mir, and another 3 cosmonauts waiting on Mir.

And during STS-119's return from the ISS, Soyuz TMA-14 was launched, bringing the total number of people on orbit to 13 again (3 in ISS, 7 in Discovery, and 3 in Soyuz TMA-14)

Edited August 13, 2014 by Mr Shifty

[Kryten]

And with this expanded crew, we may again see 13 people in space for a brief period, depending on Chinese plans.

[Javster]

Note that everyone who flies on Soyuz has their own personal thermoformed seat cushion adapted to their morphology. So when they rotate the Soyuz, the crew needs to transfer their cushion to the spacecraft they will be travelling down in.

Although in a bad emergency, they could probably survive with someone else's?

[Nibb31]

Although in a bad emergency, they could probably survive with someone else's?

I don't see why not. It's probably more a matter of comfort.

[xenomorph555]

I don't see why not. It's probably more a matter of comfort.

Basically to lower g force stress but perfectly fine for someone else to use.

[dharak1]

Does that mean a new record of 14? 7 in the station and 7 coming up during the transfer? Or does the other crew deorbit before the next one gets to orbit? Could we get to 16 or 17 if China has people in orbit too?

[Nibb31]

The CCDev vehicles can all carry 6 to 7 crewmembers, but in practice, they won't be ferrying more than 4 people up and down. The extra seats will be either for cargo or maybe tourists.

[dharak1]

Aw, I was hoping we would see a new record. I'm not very up to date on China's plans but how much crew is supposed to be on Tiangong 2 at once?

[Agamemnon]

usually no tourists because of indirect handovers (just in exception cases, like the one year stay in 2015... with sarah brightman as a tourist)

[dharak1]

A one year stay on the ISS? How much did that cost her? If it was something I could get in a reasonable amount of time I am going to make it my life goal to get a ticket to stay on the ISS. Not much time left though, isn't it supposed to be deorbited in 2024? Pretty sad.

[Agamemnon]

she wont stay one year on the iss... she just uses the fact that soyuz will be changed in the middle of the one year stay of kornienko/kelly for a new one and there will be one week window for a tourist (because of the direct handover)... and she pays 50 mil. for the week

[dharak1]

50 million a week? Seems like a reasonable rate compared to some hotels today. If I had the money I would for sure do it.

[Kryten]

Aw, I was hoping we would see a new record. I'm not very up to date on China's plans but how much crew is supposed to be on Tiangong 2 at once?

3. They may or may not do a very short-term six person period as a stunt, and the full station will have six during handovers (like Mir).