Could Dragon V1 be a lifeboat if need be?

[FishInferno]

So, what if there was a problem on the ISS, and the crew needed to evacuate. But for whatever reason, the Soyuz wasn't working. Could they scramble on board the Dragon (V1, not V2), undock, and reenter and land? Dragon has a pressurized cabin, but could mission control keep radio contact with the astronauts? Just a question I had.

[Tommygun]

It doesn't have life support, but maybe they could wear their space suits?

[Kryten]

Dragon v1 doesn't dock, it berths. It might sound nitpicky, but that means it takes a considerable amount of time for it to actually separate, and it requires use of Canadarm to do so. Not something you want to have to arrange in a hurry.

[FishInferno]

Dragon v1 doesn't dock, it berths. It might sound nitpicky, but that means it takes a considerable amount of time for it to actually separate, and it requires use of Canadarm to do so. Not something you want to have to arrange in a hurry.

If you had to, couldnt you detach from the ISS and then just RCS away? I never actually understood why it needs the arm to berth if it has rcs

[magnemoe]

If you had to, couldnt you detach from the ISS and then just RCS away? I never actually understood why it needs the arm to berth if it has rcs

I think it might be able to disconnect with RCS, they use the arm as its more controlled and safer and you have it where anyway.

You need the arm to berth, the tolerances is far narrower than during docking, docking clamps has guides who gives an error margins so you can be off by some cm.

Berthing don't have this guides and tolerance, main benefit is that its lighter.

[Umlüx]

in a real emergency, you wouldn't have to care about blasting the iss with rcs exhaust gasses. maybe you can even manually unlock the berthing mechanism? so i am not so sure that it would take that long.

the other question is, would the life support in the space suits last long enough? and can Dragon v1 simply initiate a reentry/landing on the fly?

[Sky_walker]

In a real emergency you'd use Soyuz, period.

[Streetwind]

The real issue is that you need someone on the ISS to close the hatch from the outside, lock it, and disengage the station's hold on the vehicle (which, as mentioned, is no trivial process).

Once Dragon is free, then yes, it could fly away by itself and perform an emergency reentry maneuver in time before astronauts riding within its pressurized section would suffocate. It would be a fairly rough landing that might cause an injury or two, and they'd probably have to wait a good while before they'd get picked up, but nothing fatal. They'd probably bed themselves on hastily piled up mounds of clothing and other soft articles, and try to buckle themselves down using the cargo mounts and straps while the Dragon is already drifting away from the station.

The fatal part would apply to the person required to stay behind... unless there's a Soyuz (or future US commercial crew vehicle) available. And if there is, why are you trying to use a cargo Dragon as a lifeboat? The station is required to always, 24/7, 365 days of the year, have as much lifeboat capacity available as there is crew. A team of 3 astronauts flies up, their Soyuz vehicle remains on the station for as long as they do, and then they return back to Earth together. At no point is there an astronaut without a vehicle.

The only scenario I can possibly imagine this happening in is if the station needs to be completely evacuated and one out of two Soyuz lifeboats somehow turns out to be inoperable (perhaps as part of the disaster that makes it necessary to evacuate, such as a major debris/meteoroid strike). Also, a cargo Dragon has to be present at the time this happens, and remain undamaged. It's an exceedingly unlikely scenario, but I'd imagine that yes, if it came down to it, it might theoretically be possible.

[sal_vager]

This thread sounds like a really good/cheesy space action movie...

you need someone on the ISS to close the hatch from the outside, lock it, and disengage the station's hold on the vehicle (which, as mentioned, is no trivial process)

I can't imagine the Dragon being ever used this way, it's too big a risk, it'd be safer to make a part of the ISS safe and await rescue.

But as Streetwind says, the Soyuz are there

[Streetwind]

An interesting additional thought regarding commercial crew vehicles... both the CST-100 and the Dragon V2 are specced for up to 7 people, but will fly only 4 (bringing the total number of astronauts on the station to 7). The rest of the space will be used for cargo. Depending on how modular the interiors of these craft will be, it might be possible to retrofit them into 7-seat configuration while in space, and evacuate the entire crew in one vehicle if the also-present Soyuz is somehow destroyed.

[FishInferno]

I know that the Soyuz stays docked to the ISS, but in this scenario, the Soyuz is rendered unusable for whatever reason.

[sal_vager]

Human life is more important than the hardware, so if it came to it and there was no better option then why wouldn't Nasa consider it?

[Nibb31]

If you had to, couldnt you detach from the ISS and then just RCS away? I never actually understood why it needs the arm to berth if it has rcs

No because the CBM needs to be manually closed and all connections cut off from inside the station. It also requires power to unlock the berthing mechanism, which makes it unsuitable in case of emergency, and that also has to be done from inside the station.

Human life is more important than the hardware, so if it came to it and there was no better option then why wouldn't Nasa consider it?

Because there is no need to. There is Soyuz.

[Guest]

Well, in theory, if both Soyuzes were damaged beyond recovery, and the station was really uninhabitable, I suppose they'd jury-rig it to work. The problem is with that it has to be released from the inside. Either they find a way around this, or someone would have to stay behind... I can see a movie, or at least a book somewhere in there (yes, I know about Gravity). They'd really need to have their backs against the wall for this to happen, though, and given the history of Soyuz, I'd bet it'd be the last thing on the station to fail. Those things are ridiculously though.

[FishInferno]

ok, so from what I gather, the Dragon connects as if it were a station module, and that is why it is harder to undock, correct?

[Kryten]

ok, so from what I gather, the Dragon connects as if it were a station module, and that is why it is harder to undock, correct?

Correct, it's the exact same mechanism (the CBM) as used to connect the US modules together.

[Damien_The_Unbeliever]

To ignore everything else - why do you assume that the Dragon-1 has a re-entry profile that is friendly to human bodies? It's a cargo vessel - it may experience acceleration forces that people, generally, shouldn't.

[hugix]

To ignore everything else - why do you assume that the Dragon-1 has a re-entry profile that is friendly to human bodies? It's a cargo vessel - it may experience acceleration forces that people, generally, shouldn't.

I could run some "simulations" in Orbiter. I have a SpaceX Add on that is quite realistic. I could run some scenarios with different entry angles.

[kStrout]

This thread sounds like a really good/cheesy space action movie...

But if it was, it would be more realistic than Gravity.

[hazarada]

Personally, I would use a fire extinguisher and a jumpsuit to make my way to an imaginary chinese space station which I would then crash on a nice beach and walk away without a scratch.

[xenomorph555]

From my perspective here are several things that make the D1 unusable for a life boat:

No supply of air, just a little circulatory fan, it takes over an hour to return to Earth, if the thing has 7 people in it they will suffocate before landing.

Nothing to sit/lay back on, it's gonna be a very dangerous ride back home.

Other reasons posted.

[xenomorph555]

I would then crash on a nice beach and walk away without a scratch.

Gravity 2: Escape for North Korea!

[EzinX]

To ignore everything else - why do you assume that the Dragon-1 has a re-entry profile that is friendly to human bodies? It's a cargo vessel - it may experience acceleration forces that people, generally, shouldn't.

Why would you assume the opposite? Higher acceleration forces are harder on the structure, even a reentry vessel intended solely for cargo it still makes sense to choose reentry angles and shielding that would be suitable for astronauts as well.

As for hatch closing, well, if everyone were in suits you could just evacuate the capsule, undock with the help of a suited astronaut inside the station, and then have that astronaut board via EVA. Assuming it's even possible to perform that maneuver inside the crowded interior of the station.

[Guest]

From my perspective here are several things that make the D1 unusable for a life boat:

No supply of air, just a little circulatory fan, it takes over an hour to return to Earth, if the thing has 7 people in it they will suffocate before landing.

Nothing to sit/lay back on, it's gonna be a very dangerous ride back home.

Other reasons posted.

High Gs on entry will probably result in some harm to the crew, but shouldn't kill them. They'd probably use everything they can to cushion the spacecraft before reentering. Oh, and there wouldn't be 7 people, but rather 6 or 5 (depending if they manage to find a way of getting it undocked with everyone inside). They've got air supplies intended for EVA and chemical CO2 scrubbers. Besides, cabin air in the Soyuz reentry capsule lasts for 48 hours (granted, there's a scrubber). They would not suffocate, at least, though they might end up permanently grounded after landing due to an incredibly rough ride.

Geez, someone really has to write up a story about this. A sudden accident (say, some sort of debris hit, maybe an exploding upper stage) damaging the Soyuzes, likely along with most of the ROS (would have to be one heck of an accident, I know), the crew scrambling to somehow find a way down, ending with the captain's heroic sacrifice and the rest escaping in a Dragon. That's a movie plot right here! And who says realistic situations don't lend themselves to writing?

Also, Dragon has no airlock, so EVAing into it like this would not be possible. This isn't KSP. Also, EVA takes a lot of preparation (well, OK, they could forgo that, but the bends would hurt like hell) and is unlikely to possible at all in this scenario. The astronaut inside would likely be doomed, unless they managed to jury-rig the ship to close the hatch from inside (astronauts are good at jury-rigging).

Edited November 22, 2014 by Guest
Merging sequential posts.

[Kryten]

As for hatch closing, well, if everyone were in suits you could just evacuate the capsule, undock with the help of a suited astronaut inside the station, and then have that astronaut board via EVA. Assuming it's even possible to perform that maneuver inside the crowded interior of the station.

You've then switched the problem with a worse one-manually opening an closing the hatch while everyone is wearing suits and one person isn't even attached to the craft. I'm not even sure if the hatch on the Dragon is big enough to fit a suited person.