1. ability to carry various mission modules, 2. airlock for EVA, etc.
Similarly, upon return from Mars the hab would decelerate and park for reuse while the crew transferred to a taxi prior to Earth return.
As for lunar missions, a Dragon would suffice just fine for the three day transit there and the same back. I know, the thing looks and seems cool, but the success of actually flying lies in low mass.
Quote from: TomH on 12/17/2013 07:34 pm Similarly, upon return from Mars the hab would decelerate and park for reuse while the crew transferred to a taxi prior to Earth return.That was and is not the plan. Takes too much DV.
Quote from: TomH on 12/17/2013 07:34 pm As for lunar missions, a Dragon would suffice just fine for the three day transit there and the same back. I know, the thing looks and seems cool, but the success of actually flying lies in low mass.We are going off topic, but what are the Astronauts going to breath, eat/drink and go to the bathroom in for over a week in a Dragon? How about power?It's a LEO taxi in it's current design, people need to get over that. Orion and Dragon are not interchangeable.
This was an interesting concept floated by someone a few years ago, but I don't think it was ever seriously considered for Orion. (A capsule more spacious than the Shuttle, with an EVA airlock and a massive cargo/science space)
Quote from: Lars_J on 12/18/2013 05:13 amThis was an interesting concept floated by someone a few years ago, but I don't think it was ever seriously considered for Orion. (A capsule more spacious than the Shuttle, with an EVA airlock and a massive cargo/science space)I think it was LM OSP, but its been a while... Still a nice one!
Quote from: Rocket Science on 12/18/2013 06:16 amQuote from: Lars_J on 12/18/2013 05:13 amThis was an interesting concept floated by someone a few years ago, but I don't think it was ever seriously considered for Orion. (A capsule more spacious than the Shuttle, with an EVA airlock and a massive cargo/science space)I think it was LM OSP, but its been a while... Still a nice one! No, I think *this* was the LM OSP (or CEV)... I've always liked this one. A smaller and more realistic take on the concept above.
I know it is not the plan. Not having to take Orion all the way to Mars and back could allow propellant to be taken which could be used for EOI, maybe in cis-Lunar space. Alternately, a deceleration stage could rendezvous with the craft as it approaches Earth on the return. This way, the hab and associated equipment could be used again rather than rebuilding everything all over again. It seems less expensive in the long run.
Quote from: newpylong on 12/17/2013 08:34 pmQuote from: TomH on 12/17/2013 07:34 pm As for lunar missions, a Dragon would suffice just fine for the three day transit there and the same back. I know, the thing looks and seems cool, but the success of actually flying lies in low mass.We are going off topic, but what are the Astronauts going to breath, eat/drink and go to the bathroom in for over a week in a Dragon? How about power?It's a LEO taxi in it's current design, people need to get over that. Orion and Dragon are not interchangeable.You are right about its current design, but part of that plan is that it evolve. And yes, the vehicles are very different-part of that difference is Orion is overbuilt and overmassed. As far as where to stow power and fluids, O2, H2O, etc. can go in the boot and be transferred through the interface. The power can be solar or LH2/LO2 fuel cells in the boot like Apollo. Musk claims Dragon's eventual variant will be Mars capable. We're only talking a pair of three day transits to and from Luna.
Jim, do you remember who came up with this design with the air bags, was it a JSC in-house study?RegardsRob
Quote from: Rocket Science on 12/18/2013 02:16 pmJim, do you remember who came up with this design with the air bags, was it a JSC in-house study?RegardsRobThat's from these guys. Second image on this page.
Quote from: TomH on 12/18/2013 01:30 amI know it is not the plan. Not having to take Orion all the way to Mars and back could allow propellant to be taken which could be used for EOI, maybe in cis-Lunar space. Alternately, a deceleration stage could rendezvous with the craft as it approaches Earth on the return. This way, the hab and associated equipment could be used again rather than rebuilding everything all over again. It seems less expensive in the long run.not really, propellant to take Orion to Mars and back is minor compared to those options.
How do you know Orion is overbuilt? They haven't even performed EFT-1 yet to verify the engineering, so how do you know? Same goes for "overmass"... at PDR it was overmass for the design
Quote from: newpylong on 12/18/2013 01:59 pmHow do you know Orion is overbuilt? They haven't even performed EFT-1 yet to verify the engineering, so how do you know? Same goes for "overmass"... at PDR it was overmass for the designI wouldn't use the term "overbuilt". MPCV did have a minor structural test failure, after all. She's not built extra thick.But I'd argue that the mass issue does bear on the discussion, both because of its severity and because of design philosophy.The CM alone is 20-25% overweight for its parachutes. Because the limit is imposed by the parachutes, thousands of pounds have to come out of the CM -- that mass can't be made up from the SM. (Incidentally, ESA is also delaying the PDR for the SM by six months because it's overweight.) Without some miraculous data from EFT-1 that the heat shield can be safely made extremely thin, it's not clear where this mass is going to come from. NASA managers themselves said as much in an AvWeek article a few months back. Although it's politically impossible, it would be good for the agency to look at alternatives to and off-ramps for MPCV. Getting the design and requirements to close may become a very expensive and Pyrrhic proposition. Whether the alternative should be some Dragon-derivative, CST-100 derivative, or other something else, I'll leave to others.It's also clear, at least to me, that the design approach underlying MPCV -- that of bringing lots of in-space capability back through the atmosphere in a capsule on every mission -- has reached, and may have exceeded, its limits. MPCV's parachutes are as big as they can be with existing technology and they may not be enough. It's also an issue that drives the size, complexity and reliability of launch abort systems. I'd argue that the better approach is focusing the capsule on what the capsule most needs to do -- getting astronauts up and down through the atmosphere as safely as possible -- and shifting other functions to an in-space module. Again, whether that in-space module is called a boot, a trunk, or a hab, and whether it's ISS-, Cygnus-, Bigelow-, or other-derived, I'll leave to others.My 2 cents... YMMV.