SpaceX Dragon 2 Updates and Discussion - Thread 3

[gemmy0I]

Crew-3 - C210

Do we know for sure they're using a new capsule for Crew-3? I recall that at the time of the IFA test, SpaceX confirmed that they intended to refurbish and refly that capsule (C205) on a crew mission. At the time it was assumed that it would be used for a non-NASA crew mission (Axiom-1 perhaps), since NASA hadn't yet approved reuse for themselves, but now that they have, C205 seems like a good candidate for Crew-3.

That said, Crew-3 and Axiom-1 are scheduled to happen in fairly short succession (~Q3/Q4 2021), so if they already earmarked C205 for the first private mission, it wouldn't be available for Crew-3. But given they've stated the refurbishment turnaround time for Crew Dragon is only a couple (~2-4 IIRC) months, they still wouldn't need to introduce a new capsule to meet demand. They should have plenty of time to turn around Resilience (C207) for either Crew-3 or Axiom-1.

Of course, all of that's moot if they've decided that they simply want to add another new capsule to the fleet, which could make sense given the expected cadence of future private missions in addition to ISS expedition flights. In that case they'd have four crew capsules in rotation (C205, C206/Endeavour, C207/Resilience, and C210), which is probably a good number to settle out at unless private demand explodes further. Alternatively, perhaps on further inspection of the IFA capsule they decided it was in some way undesirable for further use, invalidating their earlier public statement which was made before they really had a chance to tear it apart.

[cohberg]

The user has since deleted their message so take it with a grain of salt.

I'm with you on both the possible reuse of C205 + wanting the expand the fleet with C210. I would actually take it a bit further and suggest a 3rd option that SpaceX might mothball C203-C205.

SpaceX rapidly iterates through hardware and there are likely manufacturing improvements that they have made with more recent vehicles. C208 has a new anti corrosion coating on both the pressure vessel and the service section bulkhead supports. What other improvements are there under the paint? What changes in brackets / plumbing were required post burst disk? At what point is it more economical to create a new pressure vessel vs getting NASA to sign off on cutting off a bracket and welding on a new one?

[Alexphysics]

Benji Reed mentioned just last month Crew-3 would most likely be a new capsule.

[cohberg]

Benji Reed mentioned just last month Crew-3 would most likely be a new capsule.

For reference (index 52:45)

[FutureSpaceTourist]

twitter.com/thesheetztweetz/status/1328169622382796801

SpaceX president Gwynne Shotwell says that beyond Endeavour and Resilience, "we will have three additional Crew Dragon capsules, and they're all in some extent of production right now."

https://twitter.com/thesheetztweetz/status/1328170044833079298

SpaceX also plans to have 3 second-generation Cargo Dragon capsule, the first of which is set to launch on the CRS-21 mission on Dec. 2.

[Ben the Space Brit]

Completely hypothetical question:

Would the docking ports allow two Dragon-2s to dock nose-to-nose? I know that there is no planned 'twin dragon' missions but could it be done?

[kevinof]

Didn't I read somewhere (probably NSF) that the ports are not androgynous so it can't be done.

Completely hypothetical question:

Would the docking ports allow two Dragon-2s to dock nose-to-nose? I know that there is no planned 'twin dragon' missions but could it be done?

[Robotbeat]

The ports are hypothetically androgynous, but it depends on if both sides have both active and passive. Also, I think there’s some difficulty with obtaining a seal if both sides are identical, but I’m not sure that would stop a mere mechanical latching.

[eriblo]

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

[Robotbeat]

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

[Nomadd]

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?
 

[MDMoery]

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?

Heck, a more basic question would be, "Is it even possible to stage an EVA from a Crew Dragon capsule when it is in standard configured for ISS ferry flights?"  Are the pressure suits they wear now robust enough to space walk over the another spacecraft?

[kevinof]

They are not EVA suits - just pressure suits for use inside the cabin only. So no, EVA not possible from a Dragon.

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?

Heck, a more basic question would be, "Is it even possible to stage an EVA from a Crew Dragon capsule when it is in standard configured for ISS ferry flights?"  Are the pressure suits they wear now robust enough to space walk over the another spacecraft?

[Robotbeat]

They are not EVA suits - just pressure suits for use inside the cabin only. So no, EVA not possible from a Dragon.

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?

Heck, a more basic question would be, "Is it even possible to stage an EVA from a Crew Dragon capsule when it is in standard configured for ISS ferry flights?"  Are the pressure suits they wear now robust enough to space walk over the another spacecraft?

Early spacewalks were done with basically equally crappy pressure suits. I wouldn't use that as proof of *impossibility* without knowing more specifics.

[kevinof]

Yeah I was going to add - they don't have any portable life support for an EVA and the current connections wouldn't reach. But that could be changed/fixed I suppose. There is also limited cooling/heating so being in direct sunlight or shadow for long would also be problematic.

They are not EVA suits - just pressure suits for use inside the cabin only. So no, EVA not possible from a Dragon.

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?

Heck, a more basic question would be, "Is it even possible to stage an EVA from a Crew Dragon capsule when it is in standard configured for ISS ferry flights?"  Are the pressure suits they wear now robust enough to space walk over the another spacecraft?

Early spacewalks were done with basically equally crappy pressure suits. I wouldn't use that as proof of *impossibility* without knowing more specifics.

[Robotbeat]

Yeah. A rescue craft could bring up some hacked together portable life support systems. After docking, have the crew all put on their spacesuits (plugged into Dragon), open a hatch and shove the portable life support systems in the crippled Dragon, repressurize it, detach suit life support from the crippled Dragon and attach suit life support to the portable life support systems, and then depress again and have each crew member EVA over to the rescue craft. (the portable life support systems could handle thermal management by open-loop method... i.e. just ensure sufficient flow of air into and out of the suit at the right temperatures)

Dumb, but I can't prove it'd be impossible.

[AS-503]

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?

Heck, a more basic question would be, "Is it even possible to stage an EVA from a Crew Dragon capsule when it is in standard configured for ISS ferry flights?"  Are the pressure suits they wear now robust enough to space walk over the another spacecraft?

There is also the issue of whether or not the cabin electronics and life support have the capability to being subjected to the vac and temp. of space (and back to pressure again too).
The 1960s era soviet space vehicles could not, that is why Leonov's space walk was only possible with an airlock.

[Robotbeat]

Previous discussion:
https://forum.nasaspaceflight.com/index.php?topic=50541.msg2064904#msg2064904

Ah, yes. Dragon Crew is purely active, without passive hooks.

Doesn’t mean SpaceX couldn’t make a variant with passive hooks. That change might not be that hard. (But you’d still need a proper target, etc.)

The more I think about a rescue Dragon docking to another Dragon, the more I realize how difficult it would be.
 Has there been any serious discussion about going after a crew in a disabled Dragon?

Heck, a more basic question would be, "Is it even possible to stage an EVA from a Crew Dragon capsule when it is in standard configured for ISS ferry flights?"  Are the pressure suits they wear now robust enough to space walk over the another spacecraft?

There is also the issue of whether or not the cabin electronics and life support have the capability to being subjected to the vac and temp. of space (and back to pressure again too).
The 1960s era soviet space vehicles could not, that is why Leonov's space walk was only possible with an airlock.

Keep in mind that only a small subset of the systems need to still work after being exposed to vacuum, i.e. mainly the repressurization systems (etc). The same sort of critical subset that SpaceX already has to qualify for vacuum exposure.

If Dragon becomes a deathtrap after even a brief exposure to vacuum, there'd hardly be any point in bothering with even an IVA suit, then, would there? Don't forget that they wear their IVA suits during docking attempts, not just for launch and entry. That means Dragon's systems have to be somewhat hardened to vacuum.

[woods170]

Yeah. A rescue craft could bring up some hacked together portable life support systems. After docking, have the crew all put on their spacesuits (plugged into Dragon), open a hatch and shove the portable life support systems in the crippled Dragon, repressurize it, detach suit life support from the crippled Dragon and attach suit life support to the portable life support systems, and then depress again and have each crew member EVA over to the rescue craft. (the portable life support systems could handle thermal management by open-loop method... i.e. just ensure sufficient flow of air into and out of the suit at the right temperatures)

Dumb, but I can't prove it'd be impossible.

This scenario is completely moot once you recognize the fact that a CCP vehicle (in perfect working order) can only sustain a crew of 4 for just 4-5 days.

How the heck do you launch your rescue craft in just 4 days?

Answer: you can only do so when that rescue craft is sitting ready on the pad when the in-orbit CCP vehicle gets stranded after undocking from ISS.

The reason why CCP vehicles are thoroughly checked-out, while still docked to ISS, is to make sure they don't get disabled after undocking.

The only scenario where a CCP vehicle is disabled after undocking, which does NOT involve a massive catastrophic systems failure (despite all the inbuilt redundancies), is a scenario involving a catastrophic MMOD collision. Such catastrophic MMOD collision requires a substantial piece of MMOD, and those are tracked from the ground. Their orbits are predictable and both the ISS and CCP vehicles can be steered around them.

Summarizing: a scenario where a CCP vehicle becomes disabled (stranded) in orbit after undocking from ISS, but prior to reentry burn, is extremely unlikely. Which explains perfectly why no credible mitigation scenarios exist.

[Robotbeat]

Yeah. A rescue craft could bring up some hacked together portable life support systems. After docking, have the crew all put on their spacesuits (plugged into Dragon), open a hatch and shove the portable life support systems in the crippled Dragon, repressurize it, detach suit life support from the crippled Dragon and attach suit life support to the portable life support systems, and then depress again and have each crew member EVA over to the rescue craft. (the portable life support systems could handle thermal management by open-loop method... i.e. just ensure sufficient flow of air into and out of the suit at the right temperatures)

Dumb, but I can't prove it'd be impossible.

This scenario is completely moot once you recognize the fact that a CCP vehicle (in perfect working order) can only sustain a crew of 4 for just 4-5 days.

How the heck do you launch your rescue craft in just 4 days?
...

SpaceX plausibly can do this if they happen to have a cargo dragon in processing at LC40. They launch so many Falcon 9s, they might just have some near enough to ready to attempt it. I can't prove it's impossible.


Also possible in some scenarios if there's a cargo Dragon attached to ISS. (but only if the portable life support is already on ISS and if that cargo Dragon is properly modified)