SpaceX Dragon 2 Updates and Discussion - Thread 3

[joek]

More than unlikely; none of the scenarios for non-NASA personnel transport to the ISS on CCP is credible.

NASA has stated they will not fly "tourists".  In any event the ISS does not have the capability to support additional personnel beyond 4 in the USOS (US Operating Segment) and 3 in the RUOS f(Russian Operating Segment) for an extended period (more than a few days).

These travelers would also need to bring all their supplies, ECLSS, and camp in their capsule for the duration.  Unless they could arrange to stay in the RUOS and negotiate transit rights through the USOS to the RUOS and use of RUOS facilities, and arrange for supply of such with either additional NASA flights or Russian flights.  Assuming the RUOS had the required additional space and ECLSS capabilities, which it does not.

In short, not going to happen with NASA/CCP.  If anyone not NASA crew or operating on behalf of NASA or a sanctioned NASA partner wants to visit ISS they'll need to do it through Russia.  So let's put a fork in it please?

Time to get back to Dragon 2 Updates and Discussion.

[John Alan]

Anyone consider the number 7 MAY have come about from talks with OTHER companies or groups who are looking to someday purchase LEO human transport services to a destination not yet in orbit?

Just a thought... 

[deruch]

Remember, both chosen CCP providers offered to NASA solutions that could in fact do more than NASA requirements demanded. The "evacuate the entire ISS crew" option was such an extra, offered by both Boeing and SpaceX.

Getting a bit far afield here, but...

Also remember that any bonus points based on those "extra" capabilities in the evaluation and award process ended with CCDev2 (last SAA).  With CCiCap (and move to FAR) capabilities beyond NASA's specific requirements could not be considered in the evaluation and award process, nor could providers be held to any other requirements (see CCT-REQ-1130).

Given the trials and tribulations of the program meeting basic requirements, I would not be surprised if the originally envisioned seven-seat capability was demoted to maybe-aspirational some time ago.

It couldn't be considered under the evaluation and award process for the original CCtCap contracts.  But the providers might have felt it was worth "future proofing" the design from the outset to enable full station evacuation if they thought it might be something that had a chance of being added after the fact.  Especially if they felt the same design was equally applicable to making their capsule more capable of servicing any purely commercial spaceflight endeavors that developed in the future.

[Roy_H]

SNC's Dream Chaser space plane was also designed to carry 7.

[woods170]

Remember, both chosen CCP providers offered to NASA solutions that could in fact do more than NASA requirements demanded. The "evacuate the entire ISS crew" option was such an extra, offered by both Boeing and SpaceX.

Getting a bit far afield here, but...

Also remember that any bonus points based on those "extra" capabilities in the evaluation and award process ended with CCDev2 (last SAA).  With CCiCap (and move to FAR) capabilities beyond NASA's specific requirements could not be considered in the evaluation and award process, nor could providers be held to any other requirements (see CCT-REQ-1130).

Given the trials and tribulations of the program meeting basic requirements, I would not be surprised if the originally envisioned seven-seat capability was demoted to maybe-aspirational some time ago.

Part of your post is incorrect.

For CCiCAP the use of FAR was considered and even prepared, but ultimately the CCiCAP contracts were awarded as funded SAAs, because of Congressional funding restrictions.

For example, see here:
- http://spaceref.biz/2013/08/nasa-announces-additional-commercial-crew-development-milestones.html
- https://web.archive.org/web/20120910072408/http://commercialcrew.nasa.gov/document_file_get.cfm?docID=645


The ONLY phase of CCP to see FAR-based contracts is CCtCAP, the current phase.

Also: the initial reveals of both Starliner and Crew Dragon crew -capacity was done in 2010, long before CCiCAP (let alone CCtCAP) contracts were awarded. In the earlier phases of CCP nearly all the involved contractors offered vehicles capable of transporting the entire ISS crew, which at that time was envisioned to be a seven-person crew.

It is correct that the requirements for both CCiCAP and CCtCAP contain a crew capacity of four (4) per vehicle, but assuming that the - earlier offered - seven-seat capability was demoted to a "maybe-aspirational" status is exactly that: an assumption.

[docmordrid]

Sounds like a crew of seven was on their minds in 2014,

NASA...

>
Right now, the lifeboat function on the space station is served by requiring a pair of Russian Soyuz spacecraft to be docked at all times. Each Soyuz holds three people. So with two docked, there can be six people working on the station at any one time. The crew drops to three when one Soyuz leaves and before another arrives during a procedure called an indirect handover.

There are fundamentally two capabilities a spacecraft must perform to be called a lifeboat, said NASA engineers who are working with companies developing spacecraft in the agency's Commercial Crew Program (CCP).
>
With a new American spacecraft also offering another four to seven seats, the station can host more astronauts than its current complement of six. That means more science on the station since more people would be available for research duties.
>

[clongton]

Sounds like a crew of seven was on their minds in 2014, NASA...

I'm getting the impression that early on NASA was conceptualizing replacing the full crew capacity of Shuttle so that ISS work could be more efficiently done or increased. There were times when there were 13 crew aboard the station during handovers and science took advantage of that during that week to do things that were otherwise difficult to do. That was during STS-127 and STS-131. While those 2 Shuttle crews of 7 plus the ISS crew of six (6) were the exception, a total crew complement of 11-12 during a handover were not uncommon.

All crewed spacecraft, while docked to the ISS, also serve as lifeboats. Getting back to both American spacecraft, if one of those carried a standard crew of 4 then the fully staffed ISS compliment could be increased from 6 to 7, which IIRC was the original target for an ISS crew complement. More science and less station maintenance could be done by each crew member. When required, either spacecraft could also carry 7 crew, replicating Shuttle's crew capacity. Once Dragon 2 and Starliner become operational I expect to see the ISS crew complement increase to 7 because with both a Soyuz and either American spacecraft docked the entire crew compliment could be evacuated. And when there is a Soyuz handoff the ISS crew would be increased to 10 for those 3 days, and when there was an American handoff the crew complement would be 11.

[Zed_Noir]

@Clongton

So in theory with maximum number of visiting crewed vehicles docked at the ISS, there could be as many as 20 persons onboard, at least temporarily.

Wacky idea. Have 2 commercial crew vehicles each bringing up 6 short stay "tourist/experiment specialist" and 1 replacement crew for the regular ISS crew. With the commercial vehicles staying at the ISS for about a week.

[FutureSpaceTourist]

Cross-posting, follow-ups better in original thread:

Gerst says NASA has margin on ISS for commercial crew to accommodate delays until January, 2020.

https://twitter.com/sciguyspace/status/1034134063161008133

He also mentioned that NASA is in discussions with @SpaceX about possibly making their second test flight into an operational mission as well.

https://twitter.com/sciguyspace/status/1034134232459816961

[whitelancer64]

@Clongton

So in theory with maximum number of visiting crewed vehicles docked at the ISS, there could be as many as 20 persons onboard, at least temporarily.

Wacky idea. Have 2 commercial crew vehicles each bringing up 6 short stay "tourist/experiment specialist" and 1 replacement crew for the regular ISS crew. With the commercial vehicles staying at the ISS for about a week.

I don't think the life support systems on the ISS would be able to handle that, as I'm pretty sure they were designed for a crew of up to 7. The Shuttle provided additional life support and crew accommodations when it was docked with its extra 7. The commercial crew vehicles would have to serve as makeshift bunkhouses and would their life support systems would have to be kept on and connected up to the ISS somehow. Might be plausible for a short stay.

[clongton]

@Clongton

So in theory with maximum number of visiting crewed vehicles docked at the ISS, there could be as many as 20 persons onboard, at least temporarily.

Wacky idea. Have 2 commercial crew vehicles each bringing up 6 short stay "tourist/experiment specialist" and 1 replacement crew for the regular ISS crew. With the commercial vehicles staying at the ISS for about a week.

No. Maximum possible crew aboard the ISS, *IF* ISS crew size is increased to 7, would be 14 (7 aboard ISS and 7 aboard an  American spacecraft). There will never be a time when there is a full ISS crew plus 2 maxed out American spacecraft docked at the same time. Just like those (2) 13-crew missions, the spacecraft crew would spend a lot of time aboard their own spacecraft so as to not over-tax the ISS ECLAS.

[Nate_Trost]

Is the ECLSS in the Dragon 2 even capable of supporting more than 4 astronauts? If SpaceX is all-in on BFS for the future, I kind of doubt there are plans to extend Dragon 2 beyond what is required to fulfill the Commercial Crew contract.

[Lar]

Can ISS ECLSS support 20 people even for a short time?

Is that question on topic?

Answers I have no idea and probably not in that specific order.

[Herb Schaltegger]

@Clongton

So in theory with maximum number of visiting crewed vehicles docked at the ISS, there could be as many as 20 persons onboard, at least temporarily.

Wacky idea. Have 2 commercial crew vehicles each bringing up 6 short stay "tourist/experiment specialist" and 1 replacement crew for the regular ISS crew. With the commercial vehicles staying at the ISS for about a week.

I don't think the life support systems on the ISS would be able to handle that, as I'm pretty sure they were designed for a crew of up to 7.

Originallly everything for the US side was spec'd for nomimal operations for 4-crew for each of two fully-independent ECLSS ARS racks. Each rack and all the ARS equipment inside was also specified for independent 8-crew operation for up to 30 days if necessary in the event of a failure in the other rack that could not be repaired, ameliorated or worked around in some other manner.

All that went out the window in terms of specs and qualification requirements during the SSF --> ISS morph, but by then the main hardware had been designed and qual testing for most or all of it was well underway.

Whether any of that vestigial capability remains part of the operating software and hardware limits these days, however, is open to question.

[clongton]

Is the ECLSS in the Dragon 2 even capable of supporting more than 4 astronauts? If SpaceX is all-in on BFS for the future, I kind of doubt there are plans to extend Dragon 2 beyond what is required to fulfill the Commercial Crew contract.

Dragon ECLAS was designed from the beginning for 7 crew.

[jbenton]

@Clongton

So in theory with maximum number of visiting crewed vehicles docked at the ISS, there could be as many as 20 persons onboard, at least temporarily.

Wacky idea. Have 2 commercial crew vehicles each bringing up 6 short stay "tourist/experiment specialist" and 1 replacement crew for the regular ISS crew. With the commercial vehicles staying at the ISS for about a week.

No. Maximum possible crew aboard the ISS, *IF* ISS crew size is increased to 7, would be 14 (7 aboard ISS and 7 aboard an  American spacecraft). There will never be a time when there is a full ISS crew plus 2 maxed out American spacecraft docked at the same time. Just like those (2) 13-crew missions, the spacecraft crew would spend a lot of time aboard their own spacecraft so as to not over-tax the ISS ECLAS.

Is the ECLSS in the Dragon 2 even capable of supporting more than 4 astronauts? If SpaceX is all-in on BFS for the future, I kind of doubt there are plans to extend Dragon 2 beyond what is required to fulfill the Commercial Crew contract.

Dragon ECLAS was designed from the beginning for 7 crew.

So both Dragon and Starliner could dock with the ISS for a fortnight (typical length of a Shuttle mission IIRC) to provide sort of a "surge capacity" of a temporary 14 member crew to the ISS? (assuming a 7-person crew on ISS at any given time)

Dragon and Starliner could both fly twice a year that way.

I'm asking from a technical standpoint, not a funding one.

[jpo234]

Can someone explain this detail from the DM1 presentation? Landing Legs???

[lucspace]

@ jpo234, could you please link the complete presentation?

[jpo234]

@ jpo234, could you please link the complete presentation?

It's in the CCtCAP thread: https://forum.nasaspaceflight.com/index.php?topic=35717.msg1850880#msg1850880

[lucspace]

Thanks!