Author Topic: Crew Dragon Mission Life Extension: Free-Flying, Uncrewed Duration  (Read 14102 times)

Online TheRadicalModerate

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A late thought. Station keeping propellant shouldn't be a problem. Even at VLEO the orbit decay shouldn't be all that much and there should be plenty of propellant for a small boost or two. That's strictly a gut estimate.

What would be a problem would be attitude control - especially at VLEO. I'd classify modifying the current tanks as non-trivial. Adding in a tapoff from extra tanks in the trunk? Again not trivial, but trivial enough?

Good point on the attitude control, especially since you're getting power from the trunk PV.

We could run out the per-orbit delta-v loss with a decent drag equation, assuming the nadir point remains constant.  But figuring out the torques on that nadir point probably requires CFD.

My main takeaway from this (incomplete) exercise is that the depot may be expensive to store in VLEO for months/years at a time.  But VLEO is probably the only place the depot is safe from MMOD--and other birds are safe from the depot, should it become MMOD.

If the power budget can cover it, maybe small reaction wheels in the trunk?

Might work.  D2's pretty big, though, and the bulk of the mass is above the trunk. 

You'd need the reaction wheels completely powered down and unloaded when the crew was on board.  Otherwise, crew-cert would be a nightmare.

If you're maintaining a constant nadir in orbit, do you come back to the same true anomaly with the reaction wheels approximately unloaded?

Online TheRadicalModerate

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Installed a few Starlink Argon thrusters in the trunk as RCS for fine attitude control. As long as you don't need quick attitude adjustments.

Bonus of some orbit change capability.

Seems like a big change, especially with the plumbing.  And D2 is gonna be about 12t, which is at least a factor of 6 more than a Starlink v2 maxi.

Online TheRadicalModerate

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There is one consumable in the ECLSS not yet discussed. The activated carbon filters.


I expect that there's a lot of plastic in the D2 interior. Plastic outgasses just the stuff that the carbon filter traps. Should be an easy fix. More filters.

Bear in mind that there are no crew to swap the extra filters, so you need a larger capacity manifold if LiOH really gets significantly depleted by non-CO2 organics.

Might be kinda shades of Apollo 13.  I wonder if SpaceX would insist on producing their own socks.

Worth thinking about.
« Last Edit: 10/12/2023 09:47 pm by TheRadicalModerate »

Offline OTV Booster

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Does anybody have a clue how the trunk radiator and the D2 are connected? I seriously doubt that it's through the heat shield. That leaves a connection somewhere on the side of the craft.


The connection can't be too close to the bottom or there will be thermal problems during EDL. Even if the materials can take it there would be unnecessary thermal transmission to the interior that would call for increased nitrox flow for cooling. What I picture is QD connectors up high and the connection lines staying with the trunk when it disconnects.


From the conversation to date it doesn't look like there are any insurmountable problems in extending D2 loiter time (except maybe MMOD) but the trunk is there 'just in case'.


A hunch: The loiter limits are self imposed because they are what was planned for and qualified.

There's a side clamp doohickey on the edge of the heatshield that provides connectivity.

A late thought. Station keeping propellant shouldn't be a problem. Even at VLEO the orbit decay shouldn't be all that much and there should be plenty of propellant for a small boost or two. That's strictly a gut estimate.


What would be a problem would be attitude control - especially at VLEO. I'd classify modifying the current tanks as non-trivial. Adding in a tapoff from extra tanks in the trunk? Again not trivial, but trivial enough?

If the power budget can cover it, maybe small reaction wheels in the trunk?
If the power budget is too tight and trunk space allows, a deployable PV would be a solution. It adds system complexity but not directly to D2 and it admittedly increases the cost of the throw away part.
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Offline OTV Booster

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There is one consumable in the ECLSS not yet discussed. The activated carbon filters.


I expect that there's a lot of plastic in the D2 interior. Plastic outgasses just the stuff that the carbon filter traps. Should be an easy fix. More filters.

Bear in mind that there are no crew to swap the extra filters, so you need a larger capacity manifold if LiOH really gets significantly depleted by non-CO2 organics.

Might be kinda shades of Apollo 13.  I wonder if SpaceX would insist on producing their own socks.

Worth thinking about.
Move one Nitrox COPV cluster from the service bay to the trunk along with as many more clusters as are necessary. Use the space opened up in the service bay for larger filter packs. This assumes that the one cluster still in the service bay stays untapped throughout the flight and one cluster is sufficient for EDL cooling. SpaceX, can we have your raw engineering data? Please? Pretty please? :D


There would be some rearranging in the service bay but in my mind that shouldn't be a complexity beyond what we're discussing.


What might be an issue is moving mass around might call for a recertification of LES. Counter to this is each current D2 launch carries different unpressurized cargo masses in the trunk, so maybe it's not a problem.


Socks? Naw. They might make their own duct tape though.
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Offline OTV Booster

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Does anybody have a clue how the trunk radiator and the D2 are connected? I seriously doubt that it's through the heat shield. That leaves a connection somewhere on the side of the craft.

Here is a good shot of trunk jettison on the in-flight abort test (2:54 video, 2:24 MET).  You can see the umbilical "claw" at the bottom of the trunk as it falls away from the spacecraft.


You can see the umbilical attached to the spacecraft below and to the right of the hatch.  https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=41016.0;attach=1492554;image

Here you can see all the connection ports without the trunk attached.  https://www.aerospacemanufacturinganddesign.com/remote/aHR0cHM6Ly9jZG4uZ2llLm5ldC9maWxldXBsb2Fkcy9pbWFnZS9zcGFjZXgtdjItdW52ZWlsMDUyOTE0LXNwYWNleF82MjB4LmpwZw.lstuMblkq6I.jpg?w=948&h=533&mode=pad&anchor=middlecenter&scale=both&bgcolor=F0F1F2
Thanks. That's just what I was looking for.


So if they add services delivered from the trunk they'd add a superset of connectors on the claw. Any D2/trunk used for long duration would need minor connector modifications. Shouldn't be a big issue.



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Offline Zed_Noir

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Installed a few Starlink Argon thrusters in the trunk as RCS for fine attitude control. As long as you don't need quick attitude adjustments.

Bonus of some orbit change capability.

Seems like a big change, especially with the plumbing.  And D2 is gonna be about 12t, which is at least a factor of 6 more than a Starlink v2 maxi.
There will power conduit cables, no plumbing. Local Argon reservoir tanks inside the trunk for each thruster.

The proposed add-on Argon thrusters takes longer burns to get results. But the Dragon capsule got plenty of time for extended thruster burns.

Online TheRadicalModerate

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Move one Nitrox COPV cluster from the service bay to the trunk along with as many more clusters as are necessary. Use the space opened up in the service bay for larger filter packs.

I'm pretty sure the LiOH system is inside the pressure vessel.  But they could trade a bit of pressurized cargo space for another pack.

Even what you described above is enough to make the D2/LSS kludge less palatable.  Absolute minimum modifications are the way to go.

Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.

Offline DanClemmensen

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Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
Apparently the pressurized volume of D2 is about 9.3 m3, while the pressurized volume of the HLS OTV is about 1000 m3.  Just open the hatch and set up a blower to dilute the volatiles by a factor of 100. And change the filters also, of course.

Online TheRadicalModerate

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Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
Apparently the pressurized volume of D2 is about 9.3 m3, while the pressurized volume of the HLS OTV is about 1000 m3.  Just open the hatch and set up a blower to dilute the volatiles by a factor of 100. And change the filters also, of course.

It can't be the full 1000m, because you need some unpressurized volume for the airlocks and the rest of the "garage".  And there's nothing to say that SpaceX has to build out as much volume as possible in the rest of the payload bay.  Volume requires more ECLSS:  More fans, more dehumidification, more thermal control, etc.

I've been assuming that the pressurized crew module, with all of its consumables and the meatware, is about 15t.  That's probably at least twice the mass of the D2's pressurized system.  At a guess, that could allow many tens of times the volume of the D2.  But we obviously don't know how pressurized volume and system mass scale with each other.

I'd be a little surprised if the LSS pressurized crew module volume, excluding the airlocks, was more than 300-400m.  Still, that's huge.  So yeah, any outgassing that couldn't get scrubbed from the D2 in free-flight probably wouldn't hurt the crew when diluted by the larger LSS volume.

There are probably contingencies where you'd want to minimize the time between LSS-D2 RPOD and when the D2 deorbited.  It's probably faster to let the D2 clean itself with new filters than to wait for the LSS to dilute things.

Offline Barley

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Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
Apparently the pressurized volume of D2 is about 9.3 m3, while the pressurized volume of the HLS OTV is about 1000 m3.  Just open the hatch and set up a blower to dilute the volatiles by a factor of 100. And change the filters also, of course.
This assumes the air in the OTV is "good".  It's probably worse in at least some ways.  (Higher humidity and CO2 for a start).  Mixing the air might dilute volatiles from the D2 but it could overwhelm parts of the D2 filters.  At the least you probably want to be able to change the filters after the transfer is complete and the hatch sealed.

For contingencies it would be interesting to know if the transfer could be done in spacesuits and the decent completed before the crew expire from heat exhaustion.  This could accommodate "bad" air or even a leak that leaves the D2 unpressurized.

Offline DanClemmensen

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Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
Apparently the pressurized volume of D2 is about 9.3 m3, while the pressurized volume of the HLS OTV is about 1000 m3.  Just open the hatch and set up a blower to dilute the volatiles by a factor of 100. And change the filters also, of course.
This assumes the air in the OTV is "good".  It's probably worse in at least some ways.  (Higher humidity and CO2 for a start).  Mixing the air might dilute volatiles from the D2 but it could overwhelm parts of the D2 filters.  At the least you probably want to be able to change the filters after the transfer is complete and the hatch sealed.

For contingencies it would be interesting to know if the transfer could be done in spacesuits and the decent completed before the crew expire from heat exhaustion.  This could accommodate "bad" air or even a leak that leaves the D2 unpressurized.
9.3 M3 of air at 1.2 kg/M3 has a mass of 11.16 kg. Just carry an extra reload of air. Vent the D2 to space and refill. Presumably D2 already has at least one refill, so an increase of the size of the refill tank should not be  big deal. For a mission that includes HLS OTV or any other large companion, the companion can carry this refill.

Online TheRadicalModerate

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Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
Apparently the pressurized volume of D2 is about 9.3 m3, while the pressurized volume of the HLS OTV is about 1000 m3.  Just open the hatch and set up a blower to dilute the volatiles by a factor of 100. And change the filters also, of course.
This assumes the air in the OTV is "good".  It's probably worse in at least some ways.  (Higher humidity and CO2 for a start).  Mixing the air might dilute volatiles from the D2 but it could overwhelm parts of the D2 filters.  At the least you probably want to be able to change the filters after the transfer is complete and the hatch sealed.

There are people in the OTV, so I'd hope the air is good.  If there are differences in the humidity specs for HLS and D2, that sounds like a "Doctor, Doctor, it hurts when I do this" kind of problem:  don't do that.

Quote
For contingencies it would be interesting to know if the transfer could be done in spacesuits and the decent completed before the crew expire from heat exhaustion.  This could accommodate "bad" air or even a leak that leaves the D2 unpressurized.

As long as you can briefly unplug the suit umbilical, this is easy, as long as the OTV-LSS umbilicals are long enough to get into the D2 seats:

1) Plug into OTV-LSS suit air system with long umbilicals.
2) Depressurize the OTV-LSS.
3) Open hatch to depressurized D2.
4) Crew goes down tunnel, climbs into D2 seats.
5) Crew unplugs OTV-LSS umbilicals and plugs into D2 umbilicals.
6) Stupid problem:  You need a way to retract the OTV umbilicals back into the OTV so you can close the hatch.
7) Undock and get thee to EDL, quickly.

This is kinda why I was suggesting that the kludge conops might mandate a D2 on warm-standby.  It could be for the next crew mission to ISS or CLD.  It doesn't need to be mounted on an F9 yet, but it would have have the hypergolics provisioned, and any cargo would either have to be removable or in such a state that it's launchable in a day or two.

Offline OTV Booster

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<snip>
A late thought. Station keeping propellant shouldn't be a problem. Even at VLEO the orbit decay shouldn't be all that much and there should be plenty of propellant for a small boost or two. That's strictly a gut estimate.


What would be a problem would be attitude control - especially at VLEO. I'd classify modifying the current tanks as non-trivial. Adding in a tapoff from extra tanks in the trunk? Again not trivial, but trivial enough?

If the power budget can cover it, maybe small reaction wheels in the trunk?
Installed a few Starlink Argon thrusters in the trunk as RCS for fine attitude control. As long as you don't need quick attitude adjustments.

Bonus of some orbit change capability.
I noodled the problem of a dumbbell mass distribution on LEO a while back (30 years?), and mascons could set it tumbling. The problem is cumulative. Thrusters would have to counter the input of each mascon on every orbit. IIRC, the mass distribution is critical. If it's evenly distributed the problem is minimized - I think.


Not really sure how this impacts Dragon specifically. The starlinks are quite a bit lighter so I'm dubious. There's also the energy budget to look at. Reaction wheels or Control Moment Gyros might be more power efficient. It calls for a closer look than I'm capable of.
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Offline DanClemmensen

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This assumes the air in the OTV is "good".  It's probably worse in at least some ways.  (Higher humidity and CO2 for a start).  Mixing the air might dilute volatiles from the D2 but it could overwhelm parts of the D2 filters.  At the least you probably want to be able to change the filters after the transfer is complete and the hatch sealed.
CCP Dragons are currently sustained for six months by being connected to the ISS. The ISS has been in space and continuously occupied for about 23 years, with occupancy of seven or more for much of that time. I've never seen any comments on the subject, but I suspect it's fairly funky by now. An HLS acting as an OTV will be a new spacecraft with a pressurized volume about the same as the ISS. it will have been occupied by a crew of four for a month or less. I doubt its air will be worse than ISS air.

Offline OTV Booster

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A late thought. Station keeping propellant shouldn't be a problem. Even at VLEO the orbit decay shouldn't be all that much and there should be plenty of propellant for a small boost or two. That's strictly a gut estimate.

What would be a problem would be attitude control - especially at VLEO. I'd classify modifying the current tanks as non-trivial. Adding in a tapoff from extra tanks in the trunk? Again not trivial, but trivial enough?

Good point on the attitude control, especially since you're getting power from the trunk PV.

We could run out the per-orbit delta-v loss with a decent drag equation, assuming the nadir point remains constant.  But figuring out the torques on that nadir point probably requires CFD.

My main takeaway from this (incomplete) exercise is that the depot may be expensive to store in VLEO for months/years at a time.  But VLEO is probably the only place the depot is safe from MMOD--and other birds are safe from the depot, should it become MMOD.

If the power budget can cover it, maybe small reaction wheels in the trunk?

Might work.  D2's pretty big, though, and the bulk of the mass is above the trunk. 

You'd need the reaction wheels completely powered down and unloaded when the crew was on board.  Otherwise, crew-cert would be a nightmare.

If you're maintaining a constant nadir in orbit, do you come back to the same true anomaly with the reaction wheels approximately unloaded?
I don't think atmospherics is the problem for attitude control. It's mascons, especially down low.


Mascons cause pitch up/down, depending on vehicle mass distribution, with yaw added if the capsule is not passing over dead center. The problem is intermittent, so starting with stopped reaction wheels, spin one up for for pitch and another for yaw control as needed. When they eventually approach saturation, use the roll wheel to go nadir down temporarily, or spin 180 in either pitch or yaw to temporarily point the other way. In the new position pitch and yaw corrections desaturate the wheels.


One possible problem with this is that moving to the new temporary position will have to fight some gyroscopic procession that might in turn further saturate the saturated gyros. Got to thimnk on this.


The ISS uses CMG's and to desaturate they have to fire thrusters. That's what we're trying to avoid.
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Offline OTV Booster

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Move one Nitrox COPV cluster from the service bay to the trunk along with as many more clusters as are necessary. Use the space opened up in the service bay for larger filter packs.

I'm pretty sure the LiOH system is inside the pressure vessel.  But they could trade a bit of pressurized cargo space for another pack.

Even what you described above is enough to make the D2/LSS kludge less palatable.  Absolute minimum modifications are the way to go.

Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
All the filters and COPV's are in the service bay under the floor which, IIUC, is pressurized.


I think plastic out gassing is organics which would be filtered out by the charcoal filters. I don't think it would be all that much of a problem but it's the type of thing NASA pays attention to. The "new car smell" is an extreme example of what I'm talking about. Get a capsule with a few miles on the odometer and it's not a big problem unless it been parked in the sun all day.


I agree that it's better to not rearrange things if at all possible, but ya gotta do what ya gotta do. It's an option, if necessary.
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Offline OTV Booster

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Hopefully, outgassing during uncrewed free flight just results in a little extra New Spacecraft Smell when the crew gets back.  Another possibility:  when they open the hatch, somebody zips in with an oxygen mask, swaps out the last dirty cannister, retreats back into the LSS, and closes the hatch for an hour or two.
Apparently the pressurized volume of D2 is about 9.3 m3, while the pressurized volume of the HLS OTV is about 1000 m3.  Just open the hatch and set up a blower to dilute the volatiles by a factor of 100. And change the filters also, of course.
This assumes the air in the OTV is "good".  It's probably worse in at least some ways.  (Higher humidity and CO2 for a start).  Mixing the air might dilute volatiles from the D2 but it could overwhelm parts of the D2 filters.  At the least you probably want to be able to change the filters after the transfer is complete and the hatch sealed.

There are people in the OTV, so I'd hope the air is good.  If there are differences in the humidity specs for HLS and D2, that sounds like a "Doctor, Doctor, it hurts when I do this" kind of problem:  don't do that.

Quote
For contingencies it would be interesting to know if the transfer could be done in spacesuits and the decent completed before the crew expire from heat exhaustion.  This could accommodate "bad" air or even a leak that leaves the D2 unpressurized.

As long as you can briefly unplug the suit umbilical, this is easy, as long as the OTV-LSS umbilicals are long enough to get into the D2 seats:

1) Plug into OTV-LSS suit air system with long umbilicals.
2) Depressurize the OTV-LSS.
3) Open hatch to depressurized D2.
4) Crew goes down tunnel, climbs into D2 seats.
5) Crew unplugs OTV-LSS umbilicals and plugs into D2 umbilicals.
6) Stupid problem:  You need a way to retract the OTV umbilicals back into the OTV so you can close the hatch.
7) Undock and get thee to EDL, quickly.

This is kinda why I was suggesting that the kludge conops might mandate a D2 on warm-standby.  It could be for the next crew mission to ISS or CLD.  It doesn't need to be mounted on an F9 yet, but it would have have the hypergolics provisioned, and any cargo would either have to be removable or in such a state that it's launchable in a day or two.
Have a short umbilical extension of a few feet that reaches from the D2 seats to the hatch, plus a bit. Have a bracket just inside the hatch that holds the suit end of the extension with the other end already plugged into the seat. Have a corresponding bracket inside the OTV to hold the OTV side umbilical.


First through third crew entering the dragon takes an umbilical off the dragon side bracket that corresponds to their seat, disconnects the OTV umbilical and connects the Dragon umbilical, then passes the OTV umbilical to a crew member waiting to enter who stows the umbilical in the OTV side bracket. The last to enter goes in only far enough that another crew member can swap the connections, then they rise up back into the OTV far enough to allow stowing of the umbilical which has been placed in their hand by a cooperative crew mate. Last one in, close the doors.


Once in their seat each crew member disconnects the short extension and plugs into their normal receptacle, then they put the extension in the glove box. Don't all spacecraft have a glove box? Or maybe they can use a velcro cable wrap to snub up the extension and keep it on.
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Online TheRadicalModerate

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Or instead of all this extra unneeded "engineering", lets just use what SpaceX has already designed for and provided if there is an emergency.

1. Reach behind your seat for the SpaceX provided emergency breathing air bottle. Complimentary for any SpaceX flights from the Cape.
2. Attach the bottle via the standard quick attach suit umbilical port
3. Deal with contaminated atmosphere, perform any filter changes or relocate vehicle / seat with ease.

Depends on the contingency.  If you're trying to deal with the "bad air" problem, what you're suggesting probably works fine.  If you're trying to deal with a depressurized D2, the failure tree gets kinda bushy.  Three possibilities:

1) If the depressurization occurs early in the mission, or the OTV-LSS's ECLSS will handle a multi-day extension, have the crew wait for a replacement D2.

2) If a replacement D2 is unavailable, or the D2 depressurized close to or during RPOD, and the problem is fixable, the crew would need extensive time on the suit umbilicals.  Maybe the portable bottles let them get from the OTV-LSS to the D2 or vice-versa, but they'll need umbilicals long enough to do some difficult tasks.  The inside suits obviously aren't made for this kind of work, but one would think that it might be possible to do simple patching?

3) If the problem isn't fixable and the crew must use the bad D2, then the problem is fairly straightforward, albeit terrifying:  Unhook from the OTV-LSS system, use the portable bottles to transfer and seal the hatch, then plug into the D2's system, and hope that the air holds out long enough to get through EDL.

If the D2 is unpressurized, the OTV-LSS needs to be depressurized, because it's highly unlikely that there will be an airlock on the docking system.  How is that accomplished?  Does it just vent and replenish from storage, or does it have to pump down and save the cabin nitrox?  Is this new work for the OTV-LSS? 

There certainly isn't a happy ending if the HLS crew returns to find the Orion and/or Gateway depressurized.  That might militate toward NASA not caring very much about dealing with the problem, which in turn might create a problem porting the HLS-LSS's system over to the OTV-LSS.
« Last Edit: 10/16/2023 10:03 pm by TheRadicalModerate »

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Or instead of all this extra unneeded "engineering", lets just use what SpaceX has already designed for and provided if there is an emergency.

1. Reach behind your seat for the SpaceX provided emergency breathing air bottle. Complimentary for any SpaceX flights from the Cape.
2. Attach the bottle via the standard quick attach suit umbilical port
3. Deal with contaminated atmosphere, perform any filter changes or relocate vehicle / seat with ease.

Depends on the contingency.  If you're trying to deal with the "bad air" problem, what you're suggesting probably works fine.  If you're trying to deal with a depressurized D2, the failure tree gets kinda bushy.  Three possibilities:

1) If the depressurization occurs early in the mission, or the OTV-LSS's ECLSS will handle a multi-day extension, have the crew wait for a replacement D2.

2) If a replacement D2 is unavailable, or the D2 depressurized close to or during RPOD, and the problem is fixable, the crew would need extensive time on the suit umbilicals.  Maybe the portable bottles let them get from the OTV-LSS to the D2 or vice-versa, but they'll need umbilicals long enough to do some difficult tasks.  The inside suits obviously aren't made for this kind of work, but one would think that it might be possible to do simple patching?

3) If the problem isn't fixable and the crew must use the bad D2, then the problem is fairly straightforward, albeit terrifying:  Unhook from the OTV-LSS system, use the portable bottles to transfer and seal the hatch, then plug into the D2's system, and hope that the air holds out long enough to get through EDL.

If the D2 is unpressurized, the OTV-LSS needs to be depressurized, because it's highly unlikely that there will be an airlock on the docking system.  How is that accomplished?  Does it just vent and replenish from storage, or does it have to pump down and save the cabin nitrox?  Is this new work for the OTV-LSS? 

There certainly isn't a happy ending if the HLS crew returns to find the Orion and/or Gateway depressurized.  That might militate toward NASA not caring very much about dealing with the problem, which in turn might create a problem porting the HLS-LSS's system over to the OTV-LSS.
AIUI, the suits are definitely not meant for EVA. They got no heat or cooling.


If a patch can be put on from the inside that's a plus. D2 pressure holds it in place. On the outside the pressure wants to blow it off.


Of course the hole will be inaccessible from the inside. Kinda like dropped toast always hits butter side down.
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

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