Quote from: ChrisWilson68 on 12/22/2013 11:43 pmQuote from: 411rocket on 12/18/2013 06:43 pmQuote from: Jim on 12/18/2013 05:49 pmQuote from: Zed_Noir on 12/18/2013 05:46 pmHave a wild idea. If the ISS cooling issues requires a contingency flight to bring up EMUs, parts, etc. Can SpaceX refurbished a used Dragon and use the Thiacom 6 LV & the CRS-3 Dragon trunk for such a flight? What is wrong with the existing CRS-3 Dragon?Nothing, aside from the electrical mods (waterproofing & freezer requirements) + resultant testing, may need to be hastened. But then NASA, may have already asked them, after this problem occured. As this Dragon is slated to have a EMU fixture in it anyways. I do not think, there will be another pump unit, ready for launch in the trunk section in time though. As it sounds like, it is the same type of unit changeout, as earlier this year. So they may need more spares soon.It would be a real PITA, to get any failed pump units goundside. Depess Dragon, open side or main hatch (demating req for main) put pump unit into Dragon. This would preferably in a sealed bag, could a crew transfer bag be large enough? Close & secure hatch, re-mate if needed & repress Dragon. There will be more to it, of course, but this is the only way I can think of, without hauling it through the station itself. Might be better, to send up another Dragon later, for failed ORUs, if it comes down to it.What would be the advantage of going to all that trouble as opposed to just bringing the unit into the ISS through the usual airlock and then to Dragon through the ISS? That is, if it's even worth that much trouble to bring the failed unit back down to Earth.Could the used PM have too much ammonia to justify bringing inside? That might preclude its ever returning to Earth.Edit: sorry, we should probably continue this in another thread.
Quote from: 411rocket on 12/18/2013 06:43 pmQuote from: Jim on 12/18/2013 05:49 pmQuote from: Zed_Noir on 12/18/2013 05:46 pmHave a wild idea. If the ISS cooling issues requires a contingency flight to bring up EMUs, parts, etc. Can SpaceX refurbished a used Dragon and use the Thiacom 6 LV & the CRS-3 Dragon trunk for such a flight? What is wrong with the existing CRS-3 Dragon?Nothing, aside from the electrical mods (waterproofing & freezer requirements) + resultant testing, may need to be hastened. But then NASA, may have already asked them, after this problem occured. As this Dragon is slated to have a EMU fixture in it anyways. I do not think, there will be another pump unit, ready for launch in the trunk section in time though. As it sounds like, it is the same type of unit changeout, as earlier this year. So they may need more spares soon.It would be a real PITA, to get any failed pump units goundside. Depess Dragon, open side or main hatch (demating req for main) put pump unit into Dragon. This would preferably in a sealed bag, could a crew transfer bag be large enough? Close & secure hatch, re-mate if needed & repress Dragon. There will be more to it, of course, but this is the only way I can think of, without hauling it through the station itself. Might be better, to send up another Dragon later, for failed ORUs, if it comes down to it.What would be the advantage of going to all that trouble as opposed to just bringing the unit into the ISS through the usual airlock and then to Dragon through the ISS? That is, if it's even worth that much trouble to bring the failed unit back down to Earth.
Quote from: Jim on 12/18/2013 05:49 pmQuote from: Zed_Noir on 12/18/2013 05:46 pmHave a wild idea. If the ISS cooling issues requires a contingency flight to bring up EMUs, parts, etc. Can SpaceX refurbished a used Dragon and use the Thiacom 6 LV & the CRS-3 Dragon trunk for such a flight? What is wrong with the existing CRS-3 Dragon?Nothing, aside from the electrical mods (waterproofing & freezer requirements) + resultant testing, may need to be hastened. But then NASA, may have already asked them, after this problem occured. As this Dragon is slated to have a EMU fixture in it anyways. I do not think, there will be another pump unit, ready for launch in the trunk section in time though. As it sounds like, it is the same type of unit changeout, as earlier this year. So they may need more spares soon.It would be a real PITA, to get any failed pump units goundside. Depess Dragon, open side or main hatch (demating req for main) put pump unit into Dragon. This would preferably in a sealed bag, could a crew transfer bag be large enough? Close & secure hatch, re-mate if needed & repress Dragon. There will be more to it, of course, but this is the only way I can think of, without hauling it through the station itself. Might be better, to send up another Dragon later, for failed ORUs, if it comes down to it.
Quote from: Zed_Noir on 12/18/2013 05:46 pmHave a wild idea. If the ISS cooling issues requires a contingency flight to bring up EMUs, parts, etc. Can SpaceX refurbished a used Dragon and use the Thiacom 6 LV & the CRS-3 Dragon trunk for such a flight? What is wrong with the existing CRS-3 Dragon?
Have a wild idea. If the ISS cooling issues requires a contingency flight to bring up EMUs, parts, etc. Can SpaceX refurbished a used Dragon and use the Thiacom 6 LV & the CRS-3 Dragon trunk for such a flight?
We lost a huge amount of capability when Shuttle was prematurely killed. That was the gamble with the $100 billion ISS, leaving it to the mercy of stockholders (foreign millionaires) more concerned about profit margins at commercial companies.
I love posts that begin with "It should not be a big deal to...." Generally indicates a lack of understanding of the situation and the details involved.
How much is it worth to return one of these units for closer examination? Because if you are talking about sending up a used Dragon on a special flight, you are talking serious cash. (even if you used a reused first stage too) You probably could build several new units and put one in the trunk of each subsequent CRS flight for a lot less than bringing one back on a special flight would cost.But it would be awesome to do.
I think that if ORU recovery is worth doing, then the best operational way of doing it would be to emulate Shuttle ops. The ORU should be recovered without ever bringing it inside the Station. This would entail modifying the Dragon systems so that the capsule can operate unpressurized. The side hatch would have to be enlarged to allow the ORU to be loaded or unloaded by hand or with the SSRMS.I don't think either of these modifications will be simple or cheap. (The hatch enlargement may not be physically possible.) It would be equivalent to producing a specialized recovery vehicle. There would have to be a very good reason for recovery.
Why would one need to enlarge the side hatch?Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?
Quote from: ehan_light on 12/24/2013 12:28 pmWhy would one need to enlarge the side hatch?Why not simply hold the Dragon capsule with the Canadarm2 in about 1.5 meter distance from the station. One can open the hatch at the top and together with the second person they can maneuver the ORU through the hatch and secure [it] inside with as example straps?Because an EVA person is going to have trouble opening the hatch, there will be no handholdsBut worse, they won't be able to fit in the dragon with the package to install it.Also, can the Dragon avionics work in a vacuum?
If the Dragon is going to be grappled by the Canadarm the entire time, the Dragon doesn't need its RCS or sensors, so you could think about doing the operation with the avionics powered down --- which trades the cooling problem for a few others (like reinitializing everything on power up, and making sure that there isn't anything there which could conceivably get screwed up by just getting exposed to a vacuum).
Quote from: rst on 12/24/2013 04:30 pmIf the Dragon is going to be grappled by the Canadarm the entire time, the Dragon doesn't need its RCS or sensors, so you could think about doing the operation with the avionics powered down --- which trades the cooling problem for a few others (like reinitializing everything on power up, and making sure that there isn't anything there which could conceivably get screwed up by just getting exposed to a vacuum).What is going to happen after it is power up, there still is no air?
There needs to be lighting for the crew to work inside it.
Also, can the Dragon avionics work in a vacuum?
Would also need to make sure they don't depend on convection for electronics cooling.