Referencing this CNN article:
in which it is mentioned that the Starliner can remain at the ISS for up to 45 days if needed.
What limits its stay to 45 days?
I’m not seeing any articles that expand on the “45 days” part beyond that same sentence. If youtuber Scott Manley covers this, I’m sure he’ll explain it.
But the ship can only stay docked on the ISS for a total of 45 days due to limited fuel on the orbit laboratory
From this Daily Mail article Boeing Starliner return date delayed again as NASA races to fix thrusters and plug leaks amid fears its astronauts will be 'stranded in space' | Daily Mail Online which may be cribbed from this paywalled WSJ article https://www.wsj.com/science/space-astronomy/boeing-sent-two-astronauts-into-space-now-it-needs-to-get-them-home-99d96633?mod=hp_lead_pos8
Nvm, dumb joke
This is surprising since many other capsules stay there for a long time (Soyuz IIRC has one sitting there for several months or more). Possibly that’s how long before the thruster fuel leak becomes a problem?
Just speculation but it is probably a combination of qualification limits, battery self-discharge rates, and any consumables that the vehicle may use while docked, possibly further limited by the anomalous helium gas leak rates they’ve been experiencing. Starliner is not intended to be a long duration spacecraft or to ever fly beyond Low Earth Orbit (LEO); it basically flies crew up to the ISS and after a stay of no more than a couple of weeks flies down other crew.
By comparison, the Space Transportation System had about a 10-11 day standard duration, and those shuttles equipped with the Extended Duration Orbiter (EDO0 pallet (Columbia and Endeavor) were rated for mission duration extended to 16 days (longest Shuttle mission was actually 17 days and change); with a dual EDO pallet mission duration could have been potentially extended to 28 days but this was never done because of a lack of mission need and physiological concerns with the ability of the pilot to perform the terminal landing procedures after that duration in freefall. The EDO pallet was removed from Endeavor when it started to be used for ISS assembly for weight reasons.
The Soyuz but it was developed from the start as a long duration spacecraft to support the Salyut program (and the secret Almaz space platforms) back when both the Soviet Union and the United States were regarding crewed space stations and rapid orbital flights as critical from both a surveillance and strategic warfare perspective. The US Air Force did considerable studies on a “Blue Gemini” system that would be capable of extended duration spaceflight beyond LEO as well as the Manned Orbiting Laboratory (MOL) before determining that neither was particularly advantageous compared to uncrewed capabilities in surveillance satellites, and so there was little focus on developing extended duration flight for military Earth orbit missions.
Stranger
Both Crew Dragon and Starliner are designed to remain docked at the ISS for up to 210 days, as per the requirements of the Commercial Crew program:
A nominal stay at the station is 180 days, which Crew Dragon has already demonstrated. Presumably, the 210 days gives them a bit of margin in case of delays.
The 45 days appears to be a function of the current mission, which is still considered a test flight (like the Crew Dragon test flight, it carried only two astronauts instead of the nominal four). I’m sure this will be uprated to the 210 day requirement once they work out some of the bugs.
And if I’m Elon, I would publicly announce that I have Crew Dragon prepped and ready to go.* 1 astronaut takes it up, 3 hitch a ride home.
I actually called my SEP IRA manager today to make sure I didn’t have anything invested in Boeing. I didn’t. He dumped my holdings months ago.
* Probably I wouldn’t announce it. Just quietly make it ready and let NASA know on the down-low.
I suspect that in a real “evacuate or die” scenario, one Crew Dragon could easily handle several more passengers strapped in where the cargo return bags would be. Might not be super comfortable but it would work.
Crew Dragon Endeavor has already spent more time in space than any Space Shuttle (nearly 600 days, and including one stay of 199 days). Granted, that was over multiple flights and so consumables are a problem, but the capsule is certainly qualified for long durations. Endeavor is actually docked at the ISS now and could serve as a lifeboat.
Not sure if any capsules are ready to go, though they have 4 total so it wouldn’t surprise me if at least one has finished refurbishment. And they certainly have the rockets to spare. I think they can handle delaying a Starlink mission by couple of days.
They have Crew Dragon launches planned for mid-July (private flight on Resilience) and sometime in August (ISS mission on Endurance). I would imagine one or both of these is either already flight-capable or could be on short notice in case of emergency.
To heck with Starliner, I want to see a crewed Dreamchaser traveling to and from the ISS.
More delays:
Do they have any capability to fix anything up there?
Probably not a lot astronauts can do to fix a propulsion pressurization system. They do have tools and spares for the ISS itself, but for a new vehicle?
So is there another way for them to return? Hopefully without having to ask Putin for a Soyuz?
Definitely no need for Soyuz. There’s a Crew Dragon already up there. And as Zakalwe said, two others that are in various stages of prep for other missions that could probably be repurposed.
One issue is that the flight suits are different between Dragon and Starliner, and aren’t compatible. They could make the trip without suits, but that leaves them without a backup for depressurization or some other event. They could probably send up a capsule with some empty suits, though they’d have to figure out the sizing. Seems like NASA must have some contingency plans for this kind of thing, but I don’t know what those are.
“Well, I suggest you gentleman invent a way to put a square peg in a round hole…rapidly.”
- Gene Kranz (according to the documentary Apollo 13)
Upon reflection, the Polaris Dawn craft is probably a non-starter. It has no docking adapter–SpaceX swapped that with an EVA hatch. If anyone is capable of swapping that back with a docking adapter in record time, SpaceX is, but it’s not a trivial process and I suspect moving the Crew-9 mission forward would be faster.
All that said, I think there’s a pretty low probability of anything like that happening. I get the impression that NASA is delaying the Starliner return because they can, and not because there’s an actual significant safety issue. There are some bugs that they want to gather info on while they have the chance, but they don’t seem to be critical ones.
Good catch. I had forgotten that Polaris Dawn Reliance was the EVA one. It appears not to have had a docking hatch since it’s first flight. Before the EVA hatch, it just had a big-ass window.
Crew-9 Endurance is probably a little over halfway ready. Typical turnaround is 5 months and it landed back in early March. Freedom landed in February and so theoretically should be almost done, and is typically used for short-duration missions, which this would most likely be. Endeavor is, of course, already docked at the ISS and couldn’t be used unless it was replaced.
The fifth Crew Dragon is still being built with no completion date announced as of yet that I can find.
Interesting article I read today (unfortunately I can’t find the damn thing again since I read it on a news aggregator app):
Boeing, per it’s Commercial Crew Program contract - a contract it received at 60% MORE funding than SpaceX) must complete 8 crew flights to ISS to get their final $4.2B payment. NASA flies around 2 missions a year to ISS and ISS is only expected to be operational for another 5.5 to 6 years. So Boeing will HAVE to certify Starliner by the end of the year and then fly 8 of the 12 remaining missions to ISS (2/yr through 2030). BUT! NASA also has extended SpaceX’s contract for an additional 5 flights AFTER Crew-9 (total of 14). 12-5 = 7. I assume that IF they get Starliner working, and fly some percentage of their contracted missions, they’ll get something, but it looks like Boeing’s human spaceflight program is pretty much toast, just from a financial perspective.