Seven crew members

[Pipcard]

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

[guckyfan]

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

I think the seven crew is just to say they can do the same number of passengers as the Space Shuttle did. Bragging rights.

[Burninate]

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

The ISS program is intended to support a crew of seven.

Six has been the interim guideline while the station's lifeboat count minimum is two Soyuz capsules (with three crew each).  With a 4-person commercial crew capsule attached, and one Soyuz attached, the station can support seven safely.  NASA suggested a bonus capability in decisionmaking would be a 7-person capsule to evacuate the whole station, in order to provide contingency lifeboat access if zero Soyuz capsules are operational for some reason connected to the evacuation.  In routine operation, that extra space will be filled with non-human downmass, and I doubt Russia would voluntarily go without a single Soyuz capsule attached for any length of time.

[mheney]

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

I think the seven crew is just to say they can do the same number of passengers as the Space Shuttle did. Bragging rights.

Actually, the shuttle flew 8 on STS-61A (Challenger, 1985); and STS-71 (a Mir mission) was 7up/8 down.
So a crew size of 7 falls short of demonstrated shutle capabilites...

[pathfinder_01]

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

The commercial crew program for the ISS only needs to be able to produce an craft able to support 4( the number of U.S.  crew). Anything beyond that is just gravy and the companies have set the max. goal for each. Right now in regards to space tourism the only destination is the ISS and so an small commercial hotel is going to have to make do  with 6-7 person crafts.

In time perhaps crew capacity will grow as it did with passenger travel by air and just about every means of transit invented but it is an start.  The ISS can support an crew of 7 with surge capacity(i.e. short time and need extra cargo) of 14 and the US needs only 4. That leaves 2-3 seats that could be used for tourist or cargo at the ISS. If an totally commercial destination occurs that would leave an crew of 5-6 for an small hotel.

[Herb Schaltegger]

While we're picking nits, the ECLSS in the USOS is, almost to a "T," the very same ECLSS designed for Space Station Freedom, which was baselined for a crew of 8 - two independent ARS racks and two independent WRM system racks, each planned to support a nominal 4-person metabolic load, with capacity to handle 8 if necessary (during repairs, contingencies, etc). While the module locations for some of the racks and support equipment have changed, the basic guts of the systems haven't.

That said, the crew sizes for commercial vehicles are based on the general consensus of what's the best overall compromise between mass, cost and capability.

[baldusi]

While we're picking nits, the ECLSS in the USOS is, almost to a "T," the very same ECLSS designed for Space Station Freedom, which was baselined for a crew of 8 - two independent ARS racks and two independent WRM system racks, each planned to support a nominal 4-person metabolic load, with capacity to handle 8 if necessary (during repairs, contingencies, etc). While the module locations for some of the racks and support equipment have changed, the basic guts of the systems haven't.

That said, the crew sizes for commercial vehicles are based on the general consensus of what's the best overall compromise between mass, cost and capability.

Volume and evacuation concerns may play a part in it, too. But I guess the real issue is market. There's barely market for 8pax/yr from NASA, what's the point of carrying 10 non-existing passengers to a non existing commercial space station, if you're not going to get your money back. If there was a sudden demand, I wouldn't be surprised to see a 5m Dragon, or even an HL42 DreamChaser (at 16 passengers on a reusable Falcon Heavy, it would significantly lower the transport cost per passenger).

[sdsds]

two independent ARS racks and two independent WRM system racks

On that topic, I wonder whether you could comment any on the wikipedia coverage:
http://en.wikipedia.org/wiki/ISS_ECLSS#Air_revitalisation_system

It seems to imply (by using the singular) the ISS has only one ARS rack. Is it ... simply wrong?

Thanks in advance for any insight you can provide.... Is there a good place to read about what's really up there?

[Herb Schaltegger]

two independent ARS racks and two independent WRM system racks

On that topic, I wonder whether you could comment any on the wikipedia coverage:
http://en.wikipedia.org/wiki/ISS_ECLSS#Air_revitalisation_system

It seems to imply (by using the singular) the ISS has only one ARS rack. Is it ... simply wrong?

Thanks in advance for any insight you can provide.... Is there a good place to read about what's really up there?

Yeah, that article seems pretty out of date. I believe there are two ARS racks now, one in Node 3 ("Tranquility" I guess they're calling it now in Touchy-Feely SpaceSpeech ... ) and one in the U.S. Lab. I don't know what, exactly, they have packaged into each one but the racks were each originally intended to hold one CDRA, one TCCS, one MCA, one TCM (Trace Contaminant Monitor - basically a GC mass spectrometer), and scarred to hold a Carbon Dioxide Reduction Assembly - either a Bosch or Sabatier reactor. A Sabatier is indeed installed and operating in one of the ARS racks now, but I don't recall its location.

There's almost certainly L2 documentation on the current state - what's installed and where, but I'm too lazy to go look for it right now. It's like looking for a needle in a haystack sometimes, given the almost 20 years' worth of planning, contingency and operational documents available to dig through.

[Ben the Space Brit]

I've always thought it was a case of one pilot + a full ISS crew in the event of a total swap-out or an emergency evacuation. It's the theoretical maximum of the design, not an anticipated baseline capability.

[sdsds]

A Sabatier is indeed installed and operating in one of the ARS racks now

Very cool! Apparently it is in Node 3, unless I'm misreading this article (with pretty photos) from 2013:

http://www.nasaspaceflight.com/2013/10/iss-hardware-providing-lessons-learned-deep-space-missions/

[erioladastra]

I've always thought it was a case of one pilot + a full ISS crew in the event of a total swap-out or an emergency evacuation. It's the theoretical maximum of the design, not an anticipated baseline capability.

Nope - 4 is the baseline for commercial crew to bring the total up to 7.  That is a full USOS crew.  Pilot will be part of  the crew.

[Nomadd]

 I'm sure there are contingency plans to support Russian crew if Soyuz has to stand down for some reason.

[Moe Grills]

  The title here is? Seven Crew Members.
I assumed it referred to the capacity of the SpaceX Dragon v2.
But you mention Soyuz??? Why??
Maybe the moderator could clear things up here.

But since Seven Crew Members is the title, and Soyuz only carries one space tourist at a time, why couldn't a Dragon v2 carry two crew and five space tourists aloft?
Advantages?
1) You don't need to learn Russian.
2) You don't need to spend 6-12 months training in Russia.
3) 20-40 million dollars divided by five. And in fact, since Elon Musk pushes the economic virtues of his boosters and space business, that 4-8 million per space tourist can be reduced to perhaps only 2 million dollars per space tourist to orbit the Earth and a short visit to an inflatable Bigelow orbital facility/hotel.

[arachnitect]

  The title here is? Seven Crew Members.
I assumed it referred to the capacity of the SpaceX Dragon v2.
But you mention Soyuz??? Why??
Maybe the moderator could clear things up here.

But since Seven Crew Members is the title, and Soyuz only carries one space tourist at a time, why couldn't a Dragon v2 carry two crew and five space tourists aloft?
Advantages?
1) You don't need to learn Russian.
2) You don't need to spend 6-12 months training in Russia.
3) 20-40 million dollars divided by five. And in fact, since Elon Musk pushes the economic virtues of his boosters and space business, that 4-8 million per space tourist can be reduced to perhaps only 2 million dollars per space tourist to orbit the Earth and a short visit to an inflatable Bigelow orbital facility/hotel.

I think the question OP is asking, is something to the effect of "If our $150 Billion space station can only support 7 crew, how will commercial space stations make any money?"

If I understand the intent correctly, maybe the thread should be in commercial spaceflight general? I think placement in this topic is throwing people off.

[The Amazing Catstronaut]

I think the question OP is asking, is something to the effect of "If our $150 Billion space station can only support 7 crew, how will commercial space stations make any money?"

Bigelow modules. Cost less, higher crew.

And agreed, if this is the true topic, it needs to move.

[Pipcard]

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

[erioladastra]

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

Because they are all trying to market tourists for the ISS and possible vehicles for trips like bigelow.

[RonM]

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

Because they are all trying to market tourists for the ISS and possible vehicles for trips like bigelow.

Before Commercial Crew, when the ISS was a destination for Orion, the max crew for an Orion was seven. That capacity is probably a holdover from Orion because NASA wanted the same capacity. The actual number of crew will be four and the rest of the capacity will be cargo.

Just because you can put seven seats in a capsule doesn't mean you have to. Look at Apollo. It had a crew of three, but could carry five.

http://en.wikipedia.org/wiki/Skylab_Rescue

[arachnitect]

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

Because they are all trying to market tourists for the ISS and possible vehicles for trips like bigelow.

Not a holdover from lifeboat/acrv days?

[Herb Schaltegger]

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

Because they are all trying to market tourists for the ISS and possible vehicles for trips like bigelow.

Not a holdover from lifeboat/acrv days?

The "ACRV" dates back to Space Station Freedom designs and operational plans, and was never more than notional. There were to be two of them, each with a capacity for 4 in ordinary configurations. I don't recall whether the notional spec was to have more seats than that or not for contingencies.

[Darren_Hensley]

My research says "SSF" and "ISS" versions of the current station were manned based on CRV (old designation ACRV) lifeboats, period! The X-38 was the precursor project to the lifeboat implementation. The ISS panel decided that two docked Soyuz craft would make up for the scrapped CRV program giving tremendous returns in real dollars. Enough even to save money buying seats on the Soyuz. Thus the Full scale CRV was never built.

STS capacity had nothing to do with Commercial Crew Designs. Pure coincidence. STS could do more than 8 in an emergency if absolutely necessary based on available space in the flight decks.

So the most often sighted reasons are...
Reason 1: The cost of the CRV fleet was additional to the ferry fleet of manned capsules already scheduled to visit the ISS. Which, in congress and ESAs eyes, would be double or more to operate both systems.
Reason 2: 7 Crew members aboard the ISS vs. Six Crew members is also a large cost expenditure in terms of consumables, sleeping quarters, waste disposal, atmosphere processing and myriad of other notable mass savings. Enough to justify reduction vs meeting planned capacity.

Now to address the 7 seats of the Commercial Crew programs. The capsules 7 "Seats" were seen as a design feature that theoretically could replace a CRV for down mass in terms of bodies. The up mass of any combination of crew and pressurized cargo could be accommodated on a as needed basis. The CRV and/or capsules would go 6 months on-orbit, but no up mass (other than the ship itself) was ever intended with CRV. The 7th seat in either ship could be replaced with valuable down mass.

All return capabilities were based on a 6 month on-orbit shelf life, factored on battery cold (standby) state, Thruster fuel storage, and Docking seal longevity.
~ all sources are international partners web sites and proposal documentation from NRTS.

The bottom line is simple. Economics, not capability, drove the current policy, and design trends for both ISS manning and all CC programs. This conclusion excludes future uses of the capsules for other non-ISS LEO missions and BEO. Obviously the crew number would vary based on mission requirements.

If a docked Capsule and Soyuz(s) were at station together, choice is given rather than excluded for evacuation. Risk is present in any scenario. And if single capsule failure were an exclusion factor 6 members minimum could still return in any combination of two ships, or in the singular Commercial Crew capsule. Having no more than 6 members aboard ISS is an optimal number for any docked capsule configuration, over capacity for down mass is a happystance, under capacity planning is never intentionally allowed. A 3 seat CC ship would still allow for 6 crew to return in an emergency, a single Soyuz return for 6 crew members is out of the question.

I'm sure there are other opinions out there, but this one is mine based on extensive research into the CRV program and the recent program changes in commercial crew, and ISS manning history.

[Herb Schaltegger]

My research says "SSF" and "ISS" versions of the current station were manned based on CRV (old designation ACRV) lifeboats, period! The X-38 was the precursor project to the lifeboat implementation.

Well, you can reach whatever conclusions you want based on your extensive research. I can tell you from personal experience that the "ACRV" (Assured Crew Return Vehicle) was always depicted in Space Station Freedom system diagrams, module layouts and design planning documents as a gumdrop-shaped capsule line drawing. As far as Space Station design and operational planning people were concerned, that was it: a notional way to get 4 people down the ground no matter what (hence the "Assured" part ).  That's it. Nothing else ever mattered to the people working Space Station.

[manboy]

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

No, my question is about commercial crew vehicles, asking why all of the CCtCap candidates have a 7 crew member capacity when the ISS already has 6 crew members and is already being serviced by at least one Soyuz.

Because they are all trying to market tourists for the ISS and possible vehicles for trips like bigelow.

Before Commercial Crew, when the ISS was a destination for Orion, the max crew for an Orion was seven.

Nope, it was six.

http://www.nasa.gov/pdf/306407main_orion_crew%20_expl_vehicle.pdf

[Pipcard]

Is the ISS capable of supporting more than six crewmembers, probably with more resupply missions?

[Burninate]

Is the ISS capable of supporting more than six crewmembers, probably with more resupply missions?

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

The ISS program is intended to support a crew of seven.

Six has been the interim guideline while the station's lifeboat count minimum is two Soyuz capsules (with three crew each).  With a 4-person commercial crew capsule attached, and one Soyuz attached, the station can support seven safely.  NASA suggested a bonus capability in decisionmaking would be a 7-person capsule to evacuate the whole station, in order to provide contingency lifeboat access if zero Soyuz capsules are operational for some reason connected to the evacuation.  In routine operation, that extra space will be filled with non-human downmass, and I doubt Russia would voluntarily go without a single Soyuz capsule attached for any length of time.

While we're picking nits, the ECLSS in the USOS is, almost to a "T," the very same ECLSS designed for Space Station Freedom, which was baselined for a crew of 8 - two independent ARS racks and two independent WRM system racks, each planned to support a nominal 4-person metabolic load, with capacity to handle 8 if necessary (during repairs, contingencies, etc). While the module locations for some of the racks and support equipment have changed, the basic guts of the systems haven't.

That said, the crew sizes for commercial vehicles are based on the general consensus of what's the best overall compromise between mass, cost and capability.

Didn't these answer your question?

The ISS life support could handle 8 long-term with redundancy without changing out the life support system, or 16 if you exhaust the redundancy, but 7 is the intended crew.  Expanding the life support system with new racks is an idea, but I have no idea whether it would be effective, or whether there are upstream bottlenecks.  Additional modules which supplement the life support system in the abstract could hypothetically expand these numbers, but it may end up being more profitable if you're going to substantially increase station size, to just start over with a fresh, more scalable design, something intended to take crew numbers from 10^1 to 10^3 as it expands rather than to be the intensely political first Western attempt at a long-term modular outpost in space, with a minimal crew.  Things like the airflow topology or the control moment gyros or the solar array wing don't really permit painless growth to the point that it could sustain 20 or 30 people, so significant growth would require significant replacement of existing station functions with new modules.

One BA-2100 would be two and a half times the size of the current station.  An array of seven BA-2100's in a figure eight configuration would be seventeen times the size of the current station, and could be plumbed for much better airflow, could permit more security against MMOD strikes, could be designed with larger angular momentum exchange capacity, could be designed from the start for SEP stationkeeping, would have better thermal inertia and insulation, with more docking and berthing ports... the list goes on.

Even tin can MPLM-derived modules look pretty damn nice at, say, a 7 meter diameter standard, in the right configuration, with an emphasis on expandability and inexpensive operation, and with the lessons we have learned in the design and operation of the ISS.

[Patchouli]

Most of the commercial crew vehicles seem to have a normal capability of three to  four passengers with seven is mostly for emergencies.

[manboy]

Most of the commercial crew vehicles seem to have a normal capability of three to  four passengers with seven is mostly for emergencies.

I believe you are incorrect. The CCVs would have four seats for ISS missions, but seven seats for possible commercial spaceflights to a Bigelow space station.

[Ben the Space Brit]

Since the ISS only supports a crew of six, are they really anticipating the availability of destinations such as small commercial space hotels?

My guess is that, somewhere in the early bowels of the Commercial Crew program was a requirement to be compatible with a Launch On Need (LON) evacuation mission to the ISS - One pilot and the ability to carry all six members of the station crew. As far as I can tell, this is no longer an active mission parameter but it had its impact on all the commercial crew designs.

[FishInferno]

If my knowledge is correct, a single Bigelow module can support seven crew, while it takes all of the ISS modules combined to support seven crew.  So joining multiple Bigelow modules can produce some serious crew capacity.

[rayleighscatter]

If my knowledge is correct, a single Bigelow module can support seven crew, while it takes all of the ISS modules combined to support seven crew.  So joining multiple Bigelow modules can produce some serious crew capacity.

It's oversimplifying a bit. You can cram a lot of sardines into a small can if they don't have to do anything.

To take ISS beyond its 7 person crew would require more frequent resupply and if those extra people want to do any meaningful science I believe it would exceed the station's power.

[llanitedave]

Yep, it's not just the size of the modules.  It's the size of the solar panels you'd need.  And the heat radiators.

[baldusi]

Yep, it's not just the size of the modules.  It's the size of the solar panels you'd need.  And the heat radiators.

And the ECLSS, and the supply runs, and the rack space for experiments, and then you have experiments that affect other experiments, and tourists jumping around ruin the microgravity environment of the crystallization experiments, etc.

[A_M_Swallow]

Yep, it's not just the size of the modules.  It's the size of the solar panels you'd need.  And the heat radiators.

And the ECLSS, and the supply runs, and the rack space for experiments, and then you have experiments that affect other experiments, and tourists jumping around ruin the microgravity environment of the crystallization experiments, etc.

I suspect that the tourist spacestation and the microgravity labratory will be separate spacestations. A long term lease of a BA-330 is not that expensive.

[baldusi]

Yep, it's not just the size of the modules.  It's the size of the solar panels you'd need.  And the heat radiators.

And the ECLSS, and the supply runs, and the rack space for experiments, and then you have experiments that affect other experiments, and tourists jumping around ruin the microgravity environment of the crystallization experiments, etc.

I suspect that the tourist spacestation and the microgravity labratory will be separate spacestations. A long term lease of a BA-330 is not that expensive.

We are learning about living and working in LEO with the ISS. Once you know what is actually worth to do, and how to do it for cheap and standardized, I'm suspecting that the next batch of stations won't be a jack of all trades, but a series of cheap, highly automated smaller and standardized modules with each dedicated to a niche.