SpaceInMyBrain t1_j22srrx wrote
For those interested in a serious answer: The two issues are spacesuits and seating. Both are custom fitted. This will apply to the two solutions: A) Sending another Crew Dragon to return the 2 cosmonauts & 1 NASA astronaut and B) Adding these 3 to the return of the Dragon currently attached, making a total of 7.
This answer addresses the article. Of course if Russia launches a replacement Soyuz this will be moot. But we don't know if a Soyuz is near readiness.
Option B seems extremely unlikely even though the article makes it sound like it's under consideration. Option A is much safer and much easier to implement. Crew 6 is scheduled to launch in mid-February. That Dragon has had plenty of time to be refurbished and is probably just waiting for loading the consumables. It could be launched with 1 pilot, with 3 empty seats. Could be launched empty but NASA does like manual back-up to autonomy. Plus, the other 3 aren't familiar with Dragon's systems, something they'll need even for their brief flight. Another Dragon is due to launch the Polaris Dawn mission and may be physically available, and I've no doubt Jared Isaacman would agree to postpone the mission if NASA requested it.
Dragon seats and IVA suits are all custom fitted. However, afaik the sizing for the seats is done with various bolt-on pieces. Among the 8 crew on the 2 upcoming launches there are probably 3 seats close enough in size to the 3 unscheduled crew members. The suits will be more difficult. But again, there are a number of suits made for several upcoming flights - and ones from old flights, afaik. The crews didn't get to keep them as souvenirs. Among all these there may be some that are a "close-enough" fit for this unusual circumstance. But the SpaceX suits are a snug fit, that may not work.
IVA suits are very much desired but a descent can be made without one. It's needed in case of sudden depressurization or a fire (in which case the cabin is depressurized to starve the flames). But no American spacecraft has had a problem like this in space. The risk of making a descent in shirtsleeves is very low - definitely lower than in a Soyuz with possibly fried avionics and no way to regulate cabin temperatures. (Yes, the risk isn't zero and it did happen to a Soyuz decades ago, but that hardly applies. And geez, if anyone brings up Apollo 1, I swear you haven't paid attention to spacecraft designs since the 70s.)
Option B involves a longish answer of its own, available on request. I can only see it occurring if there's a drastic emergency requiring evacuating the ISS entirely.
TheBaenAddict t1_j23m006 wrote
I would be surprised if the Dragon planned for Polaris Dawn still has its IDA. With the planned spacewalk for Dawn there has been a lot of talk about how the docking adapter makes the entrance quite small-too small to even fit a NASA EVA suit. I've no doubt that Jared would give NASA his Dragon if asked, but it may not be possible.
SpaceInMyBrain t1_j244cxl wrote
Good point. The question we don't know the answer to is how quickly the IDA can be reinstalled but NASA is loath to accept anything quickly. Fortunately we have the Crew 6 option.
WindierGnu t1_j23obaa wrote
I hate to be that guy... But can I hear option B please? Thank you for taking the time to write this out. I found your explanation above very interesting.
SpaceInMyBrain t1_j24aclm wrote
No problem. This is actually just a copy/paste from my answer in the SpaceX Lounge.
When Crew Dragon launches it carries a small amount of cargo strapped to the floor in the standard NASA/ISS stowage bags. This also implies there are attachment points for these bags. Stuff these with soft materials and the g-forces are taken care of. Splashdown will be a bit intense but I'd rather risk small injuries vs dying in a spacecraft with fried electronics and potentially deadly internal temperatures. The space station has plenty of soft stuff like empty equipment stowage bags and especially bags and bags of dirty laundry. Doubtless there are a variety of additional straps to improvise with. IIRC some of the ubiquitous storage bags are held to the walls by a cargo netting made with flat straps.
In this scenario descending in shirtsleeves is the only option, there won't be enough umbilical ports for 7 SpaceX suits even if they were available on the station. The Russian Sokol IVA suits have a very different design to supply air to the suit for breathing and cooling.
SkillYourself t1_j248ze8 wrote
Option B is putting 7 people in a capsule with 4 seats. 3 people ride strapped down with the cargo.
It's not the safest option, but if the ISS has to be evacuated it's certainly better than being stranded in orbit and probably better than gambling on a possibly crippled Soyuz
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