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.
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.
Quote from: OTV Booster on 10/11/2023 11:56 pmDoes 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.Quote from: OTV Booster on 10/12/2023 12:10 amA 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?
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.
Quote from: OTV Booster on 10/11/2023 11:27 pmThere 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.
Quote from: OTV Booster on 10/11/2023 11:56 pmDoes 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;imageHere 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
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.
Quote from: Zed_Noir on 10/12/2023 02:18 amInstalled 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.
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.
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.
Quote from: TheRadicalModerate on 10/13/2023 05:51 amHopefully, 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.
Quote from: DanClemmensen on 10/13/2023 04:32 pmQuote from: TheRadicalModerate on 10/13/2023 05:51 amHopefully, 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.
Quote from: DanClemmensen on 10/13/2023 04:32 pmQuote from: TheRadicalModerate on 10/13/2023 05:51 amHopefully, 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.
Quote from: Asteroza on 10/12/2023 01:43 am<snip>Quote from: OTV Booster on 10/12/2023 12:10 amA 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.
<snip>Quote from: OTV Booster on 10/12/2023 12:10 amA 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?
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.
Quote from: OTV Booster on 10/12/2023 12:10 amA 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.Quote from: Asteroza on 10/12/2023 01:43 amIf 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?
Quote from: OTV Booster on 10/13/2023 01:46 amMove 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.
Quote from: Barley on 10/14/2023 07:10 pmQuote from: DanClemmensen on 10/13/2023 04:32 pmQuote from: TheRadicalModerate on 10/13/2023 05:51 amHopefully, 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.QuoteFor 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.
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 port3. Deal with contaminated atmosphere, perform any filter changes or relocate vehicle / seat with ease.
Quote from: cohberg on 10/15/2023 03:40 amOr 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 port3. 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.