CCDev to CCiCAP to CCtCAP Discussion Thread

[yg1968]

If NASA are buying seats in Dragon do they buy 2 seats for passengers or 4 ie crew + passengers. If they are leasing whole why not use all 7 seats,  transport is biggest cost of placing somebody in ISS.

NASA only needs 4 astronauts on each flight. Each astronaut stays for at least 6 months.  There is only the budget for 6 or 7 astronauts on ISS. Gerst said that they weren't sure if they had the budget for a 7th astronaut.

Since the retirement of Shuttle, there is no longer any short term visits to the ISS. What makes short term visits difficult is that the arriving US spacecraft will also serve as a lifeboat for six months. So once you get to the ISS, the next U.S. ride down is 6 months later.

[ChrisWilson68]

If NASA are buying seats in Dragon do they buy 2 seats for passengers or 4 ie crew + passengers. If they are leasing whole why not use all 7 seats,  transport is biggest cost of placing somebody in ISS.

NASA only needs 4 astronauts on each flight. Each astronaut stays for at least 6 months.  There is only the budget for 6 or 7 astronauts on ISS. Gerst said that they weren't sure if they had the budget for a 7th astronaut.

Since the retirement of Shuttle, there is no longer any short term visits to the ISS. What makes short term visits difficult is that the arriving US spacecraft will also serve as a lifeboat for six months. So once you get to the ISS, the next U.S. ride down is 6 months later.

But the replacement crew arrives before the old crew departs.  The overlap time is the time short-term visitors can stay.  They arrive on the new vehicle and go back on the vehicle that has been there for six months.

[TrevorMonty]

If NASA are buying seats in Dragon do they buy 2 seats for passengers or 4 ie crew + passengers. If they are leasing whole why not use all 7 seats,  transport is biggest cost of placing somebody in ISS.

NASA only needs 4 astronauts on each flight. Each astronaut stays for at least 6 months.  There is only the budget for 6 or 7 astronauts on ISS. Gerst said that they weren't sure if they had the budget for a 7th astronaut.

Since the retirement of Shuttle, there is no longer any short term visits to the ISS. What makes short term visits difficult is that the arriving US spacecraft will also serve as a lifeboat for six months. So once you get to the ISS, the next U.S. ride down is 6 months later.

But the replacement crew arrives before the old crew departs.  The overlap time is the time short-term visitors can stay.  They arrive on the new vehicle and go back on the vehicle that has been there for six months.

Thanks yg1968 for update.

So the issue is more of how many astronauts the ISS can support. If there is a Soyuz(3) and Dragon(7) present at one time then 10 maybe to much for the station.  If the overlap was 2 Dragons then we a looking at 14 (7+7) which is definitely too many for the station.  The only situation where spares seats could be used for short-term visitors(tourists) is if there is Dragon crew of 4 present with no Soyuz. Even then we are looking at 4+4+ upto 3 visitors. 11 maybe OK for a few days assuming everything goes to plan and return Dragon's flight is not delayed.

I'm now starting to see the reason for limiting seats to 4 per flight.

[Robotbeat]

10 or whatever is fine for short durations. It does increase consumables use, though.

[pathfinder_01]

Thanks yg1968 for update.

So the issue is more of how many astronauts the ISS can support. If there is a Soyuz(3) and Dragon(7) present at one time then 10 maybe to much for the station.  If the overlap was 2 Dragons then we a looking at 14 (7+7) which is definitely too many for the station.  The only situation where spares seats could be used for short-term visitors(tourists) is if there is Dragon crew of 4 present with no Soyuz. Even then we are looking at 4+4+ upto 3 visitors. 11 maybe OK for a few days assuming everything goes to plan and return Dragon's flight is not delayed.

I'm now starting to see the reason for limiting seats to 4 per flight.

13 People have stayed at the station short term but it takes extra consumables and they rode on the Shuttle. The commercail crew craft and Soyuz don't use the same docking ports and they are planning to have 2 for CCREW craft. The bigger problem is that they are planning to rotate the whole NASA crew at once(i.e. Arrive with 4, depart with 4 on the same spacecraft that launched arrive with 4 more crew).

The station's normal capcaity is 7 but it has a surge capacity of 14(i.e. need extra supplies).

[joek]

But the replacement crew arrives before the old crew departs.  The overlap time is the time short-term visitors can stay.  They arrive on the new vehicle and go back on the vehicle that has been there for six months.

That would be direct handover (new crew arrives before old crew leaves).  Last public information shows indirect handover (old crew leaves before new crew arrives).  Indirect handover would not allow for short term visitors without additional flights.  From NASA planning ISS module relocations to support future crew vehicles, NASASpaceFlight.com, July 2013:

However, the FPIP chart shows that, under current planning, only one commercial crew vehicle will ever be docked to the ISS at any one time, since one crew vehicle will return home at the end of its 6-month ISS stay prior to the launch of another crew vehicle, in what is known as an “indirect handover”.

Note that would also implies at least one US crew continuing to ride on Soyuz in order to ensure the US segment always has at least one US crew present, and in turn one Russian crew riding on the US crew vehicle.

So the issue is more of how many astronauts the ISS can support. If there is a Soyuz(3) and Dragon(7) present at one time then 10 maybe to much for the station.  If the overlap was 2 Dragons then we a looking at 14 (7+7) which is definitely too many for the station.  The only situation where spares seats could be used for short-term visitors(tourists) is if there is Dragon crew of 4 present with no Soyuz. Even then we are looking at 4+4+ upto 3 visitors. 11 maybe OK for a few days assuming everything goes to plan and return Dragon's flight is not delayed.

See above.  Less a matter of how many people ISS can support and more dependent on transportation and direct vs. indirect handover.  Until something changes, the only people flying will be ISS crew increments; no short term visitors.

[MP99]

Thanks yg1968 for update.

So the issue is more of how many astronauts the ISS can support. If there is a Soyuz(3) and Dragon(7) present at one time then 10 maybe to much for the station.  If the overlap was 2 Dragons then we a looking at 14 (7+7) which is definitely too many for the station.  The only situation where spares seats could be used for short-term visitors(tourists) is if there is Dragon crew of 4 present with no Soyuz. Even then we are looking at 4+4+ upto 3 visitors. 11 maybe OK for a few days assuming everything goes to plan and return Dragon's flight is not delayed.

I'm now starting to see the reason for limiting seats to 4 per flight.

13 People have stayed at the station short term but it takes extra consumables and they rode on the Shuttle.

Didn't they also use the Shuttle's accommodation, eg for sleeping?

Cheers, Martin

[clongton]

10 or whatever is fine for short durations. It does increase consumables use, though.

Shuttle routinely arrived with 7 crew. For the duration of Shuttle's visit, ISS hosted 10.

[yg1968]

But the replacement crew arrives before the old crew departs.  The overlap time is the time short-term visitors can stay.  They arrive on the new vehicle and go back on the vehicle that has been there for six months.

That would be direct handover (new crew arrives before old crew leaves).  Last public information shows indirect handover (old crew leaves before new crew arrives).  Indirect handover would not allow for short term visitors without additional flights.  From NASA planning ISS module relocations to support future crew vehicles, NASASpaceFlight.com, July 2013:

However, the FPIP chart shows that, under current planning, only one commercial crew vehicle will ever be docked to the ISS at any one time, since one crew vehicle will return home at the end of its 6-month ISS stay prior to the launch of another crew vehicle, in what is known as an “indirect handover”.

Note that would also implies at least one US crew continuing to ride on Soyuz in order to ensure the US segment always has at least one US crew present, and in turn one Russian crew riding on the US crew vehicle.

So the issue is more of how many astronauts the ISS can support. If there is a Soyuz(3) and Dragon(7) present at one time then 10 maybe to much for the station.  If the overlap was 2 Dragons then we a looking at 14 (7+7) which is definitely too many for the station.  The only situation where spares seats could be used for short-term visitors(tourists) is if there is Dragon crew of 4 present with no Soyuz. Even then we are looking at 4+4+ upto 3 visitors. 11 maybe OK for a few days assuming everything goes to plan and return Dragon's flight is not delayed.

See above.  Less a matter of how many people ISS can support and more dependent on transportation and direct vs. indirect handover.  Until something changes, the only people flying will be ISS crew increments; no short term visitors.

On this issue, McAlister said that it was up to the commercial crew provider to decide whether they wanted to use a rental or taxi system. A taxi system implies a short term visit for the pilot. McAlister admitted that a taxi system would be difficult to implement if the commercial crew provider also provides the lifeboat function. 

http://www.nasaspaceflight.com/2013/05/mcalister-discusses-commercial-crew-certification/

[clongton]

On this issue, McAlister said that it was up to crew providers whether they wanted to use a rental or taxi system. A taxi system implies a short term visit for the pilot. McAlister admitted that a taxi system would be difficult if the commercial crew providers also provides the lifeboat function. 

Originally there was to be an X-38 CRV docked at all times to the ISS to provide on-demand safe haven or emergency crew return for a full ISS crew compliment. This was in addition to the visiting Soyuz and Shuttle spacecraft. If the CRV had come to full fruition short term visits to ISS could have been the norm. It had sufficient cross range capability that if necessary the crew could abandon station at any point in its orbit and return to almost any runway in the world within a wide swath under the ISS orbital path. It would be forward thinking (perhaps wishful thinking?) if NASA were to contract an SN DreamChaser spacecraft to fill this roll.
http://en.wikipedia.org/wiki/Crew_Return_Vehicle

[Jim]

It had sufficient cross range capability that if necessary the crew could abandon station at any point in its orbit and return to almost any runway in the world

X-38 didn't use a runway

[clongton]

It had sufficient cross range capability that if necessary the crew could abandon station at any point in its orbit and return to almost any runway in the world

X-38 didn't use a runway

COULD HAVE, I said. I know it didn't need a runway. It could have set down on almost any sufficiently large open space, using its parafoil landing system. I said what I did specifically to lead into the DreamChaser comment, which does need a runway.

An operational CRV would have targeted a runway as its first choice, simply because of the emergency services available there. Lacking one, any large open space would have sufficed.

[joek]

On this issue, McAlister said that it was up to the commercial crew provider to decide whether they wanted to use a rental or taxi system. A taxi system implies a short term visit for the pilot. McAlister admitted that a taxi system would be difficult to implement if the commercial crew provider also provides the lifeboat function. 

Understood, but I think it's safe to say that the taxi model is dead without direct handover or additional flights beyond those required for normal ISS crew rotation.  Given the current path, I also question whether the taxi model will ever be needed or justified for normal ISS crew rotation, as the spacecraft crew is essentially dead weight.  Maybe in the future if there are additional flights to ferry short term ISS crew, or where the spacecraft crew are also seconded as station crew, the taxi model may make sense.

That IMHO obtains in part from current FAA regulations, which require that spacecraft crew be employees or contractors of the licensee* (the provider, such as Boeing, SpaceX, or SNC).  However, non-crew may perform crew tasks in an emergency; the FAA has stated they have made provisions for such.  In a CTS rental car model, all ISS crew would thus be considered non-crew (spaceflight participants).  The exception would be if the spacecraft crew is also seconded as ISS crew.  E.g., Boeing, SpaceX or SNC employee or contractor as spacecraft crew are also contracted by NASA as ISS crew.

In short, it appears that the need for spacecraft crew is being displaced by remote operation, on-board autonomous systems, or a combination.  The benefit of a taxi model would presumably be reduced emergency training requirements for non-crew.


* FAA definitions:

Crew means any employee or independent contractor of a licensee, transferee, or permittee, or of a contractor or subcontractor of a licensee, transferee, or permittee, who performs activities in the courseof that employment or contract directly relating to the launch, reentry, or other operation of or in a launch vehicle or reentry vehicle that carries human beings. A crew consists of flight crew and any remote operator.
...
Space flight participant means an individual, who is not crew, carried aboard a launch vehicle or reentry vehicle.

[manboy]

10 or whatever is fine for short durations. It does increase consumables use, though.

Shuttle routinely arrived with 7 crew. For the duration of Shuttle's visit, ISS hosted 10.

For three missions there were even thirteen aboard.

[ChrisWilson68]

On this issue, McAlister said that it was up to crew providers whether they wanted to use a rental or taxi system. A taxi system implies a short term visit for the pilot. McAlister admitted that a taxi system would be difficult if the commercial crew providers also provides the lifeboat function. 

Originally there was to be an X-38 CRV docked at all times to the ISS to provide on-demand safe haven or emergency crew return for a full ISS crew compliment. This was in addition to the visiting Soyuz and Shuttle spacecraft. If the CRV had come to full fruition short term visits to ISS could have been the norm. It had sufficient cross range capability that if necessary the crew could abandon station at any point in its orbit and return to almost any runway in the world within a wide swath under the ISS orbital path. It would be forward thinking (perhaps wishful thinking?) if NASA were to contract an SN DreamChaser spacecraft to fill this roll.
http://en.wikipedia.org/wiki/Crew_Return_Vehicle

If NASA were to have a crew return vehicle at this point, it would only make sense if it were one of the CCtCap vehicles.  So, if DreamChaser is one of the CCtCap vehicles, another copy could serve as a dedicated lifeboat.  Dragon and CST-100 could do it equally well if they were a CCtCap vehicle.  What would not make sense would be to use a different vehicle for a lifeboat than one of the CCtCap vehicles.  They were only contemplating that with X-38 because a shuttle orbiter was far too big and expensive to leave up there as a lifeboat.

Anyway, there's no indication they plan to have a dedicated lifeboat instead of just continuing with the plan to have the vehicle that brought the crew up stay there as their lifeboat.

[Jcc]

Isn't there also the concern about the longevity on orbit of a "lifeboat"? If they rotate out the crew vehicles that is not an issue, but leaving a vehicle there for several years and expecting it to work is risky.

[ChrisWilson68]

Isn't there also the concern about the longevity on orbit of a "lifeboat"? If they rotate out the crew vehicles that is not an issue, but leaving a vehicle there for several years and expecting it to work is risky.

Yes, absolutely, and I assume that's why the current plan is to have the crew use the vehicle they took up as a lifeboat during their stay, then bring it back down.

[joek]

Isn't there also the concern about the longevity on orbit of a "lifeboat"? If they rotate out the crew vehicles that is not an issue, but leaving a vehicle there for several years and expecting it to work is risky.

Yes, absolutely, and I assume that's why the current plan is to have the crew use the vehicle they took up as a lifeboat during their stay, then bring it back down.

Yes; CTS requirement is minimum life of 210 days on-station.  Not to mention something like a CRV would occupy a docking port.  Only two will be available for the foreseeable future on the USOS side, and IIRC nominal rule is one remain unoccupied in case there is a problem with the other.

[clongton]

Isn't there also the concern about the longevity on orbit of a "lifeboat"? If they rotate out the crew vehicles that is not an issue, but leaving a vehicle there for several years and expecting it to work is risky.

Yes, absolutely, and I assume that's why the current plan is to have the crew use the vehicle they took up as a lifeboat during their stay, then bring it back down.

Yes; CTS requirement is minimum life of 210 days on-station.  Not to mention something like a CRV would occupy a docking port.  Only two will be available for the foreseeable future on the USOS side, and IIRC nominal rule is one remain unoccupied in case there is a problem with the other.

There would be no need to leave a lifeboat docked there for "years". Just have that vehicle in the rotation schedule. That way there is always a "new" lifeboat docked.

[yg1968]

Isn't there also the concern about the longevity on orbit of a "lifeboat"? If they rotate out the crew vehicles that is not an issue, but leaving a vehicle there for several years and expecting it to work is risky.

Yes, absolutely, and I assume that's why the current plan is to have the crew use the vehicle they took up as a lifeboat during their stay, then bring it back down.

Yes; CTS requirement is minimum life of 210 days on-station.  Not to mention something like a CRV would occupy a docking port.  Only two will be available for the foreseeable future on the USOS side, and IIRC nominal rule is one remain unoccupied in case there is a problem with the other.

There would be no need to leave a lifeboat docked there for "years". Just have that vehicle in the rotation schedule. That way there is always a "new" lifeboat docked.

NASA only wants one CTS contractor starting in 2017. So SNC would have to have edge out SpaceX for the CTS contract.