Quote from: MATTBLAK on 02/23/2013 04:29 amMixed launch fleet launch sequence: 1x Falcon Heavy - Earth Departure Stage #1 (LOX/CH4 or LOX/RP1).1x Falcon Heavy with the Long Trunk Habitat/Logistics and hypergolic propulsion module.1x Falcon 9.1 with Dragon Rider Command craft and crew.1x Atlas 552 with Centaur twin engined EDS #2.If this is going to work, it has to be one launch. Everything else starts getting in the billions and is much too complex to pull off in such a short time.And no reconfiguration of the spacecraft after TMI. Imagine you are after TMI and something goes wrong with the rotation of the dragon and docking to the service module. Since you won't be able to carry EVA equipment due to mass constraints, you're dead.The following might work: the falcon heavy as it is planned now suffers very much for high energy trajectories because it is not yet optimized for those. Spacex might have a better upper stage engine available in 2018, but it is probably not a good idea to depend on their schedule estimates for something like this.So you could have a dragon with a service module with some additional living space, ECLSS, a docking adapter, and a propulsion system for some 1000m/s. Launch the stack into a highly elliptical earth orbit (28°, 20000x200km or so) using the falcon heavy upper stage, turn the dragon around and redock to the service module, and do the actual TMI using the service module, with the dragon turned around, during the next perigee pass.That way, you can abort in case something goes wrong with the reconfiguration, and you increase the TMI throwmass a lot. I think they will propose to tough it out without any additional living space. But with the payload numbers published for FH (53t to LEO, but just 12t to 28° GTO) they will need some kind of upper stage for the TMI in any case.
Mixed launch fleet launch sequence: 1x Falcon Heavy - Earth Departure Stage #1 (LOX/CH4 or LOX/RP1).1x Falcon Heavy with the Long Trunk Habitat/Logistics and hypergolic propulsion module.1x Falcon 9.1 with Dragon Rider Command craft and crew.1x Atlas 552 with Centaur twin engined EDS #2.
Quote from: rklaehn on 02/23/2013 06:42 amI think they will propose to tough it out without any additional living space. There is a limit to how much you can tough it out. Ten cubic m just is not enough for two people over 500 days, not when all the onboard equipment cuts it to half this.
I think they will propose to tough it out without any additional living space.
But without a Propellant Depot waiting at L-1 or L-2 it seems to me that any Mars or NEA mission could not be done in a single launch without that launcher being able to throw at least 35 metric tons to escape velocity.
What about using a modified Falcon 9 US as a "wet workshop", simply to give the astronauts a bit more room?
Quote from: Dalhousie on 02/23/2013 08:49 amQuote from: rklaehn on 02/23/2013 06:42 amI think they will propose to tough it out without any additional living space. There is a limit to how much you can tough it out. Ten cubic m just is not enough for two people over 500 days, not when all the onboard equipment cuts it to half this. Ten cubic meters (353 feet) per crew member might be tolerable (barely) if the following factors are taken into account: Communications with Earth are strong and reliable. The food is good, there is a vast digital entertainment library to amuse the crew, the toilet facilities are reliable, the exercise equipment is decent, even if basic... I could go on, but I think people get my drift.
Quote from: Dalhousie on 02/23/2013 08:49 amQuote from: rklaehn on 02/23/2013 06:42 amI think they will propose to tough it out without any additional living space. There is a limit to how much you can tough it out. Ten cubic m just is not enough for two people over 500 days, not when all the onboard equipment cuts it to half this. Nevertheless that is what I suspect they will propose.
Assuming a very simple life support system, you would have 5kg/man/day * 500 days * 2 pax = 5000kg for provisions. Add 1000kg for the life support system itself, 4200kg for the dragon and 1000kg for propellant for midcourse corrections, you end up with just 11.2t.
Quote from: DLR on 02/23/2013 09:46 amWhat about using a modified Falcon 9 US as a "wet workshop", simply to give the astronauts a bit more room?That would require using the F9 US to do the TMI, which is not possible unless you have an unrealistically low consumables mass budget. Also, you would have to do the conversion to habitable volume while on an interplanetary trajectory, with no way to abort if something goes wrong. An upper stage and a space station / habitable volume are both highly mass-optimized, specialized machines. They don't have that much in common except that both are pressure vessels. So conversion from one to the other is not as simple as people seem to think.For additional habitable volume you would be better off using a bigelow beam or a stripped-down dragon pressure vessel without heatshield and propulsion. But note that docking something to the dragon will block the draco engines that are most efficient for orbit correction maneuvers.
And of course it is a pretty high risk mission.
Quote from: rklaehn on 02/23/2013 09:02 amNevertheless that is what I suspect they will propose.If they propose that, then that alone is enough to kill it.
Nevertheless that is what I suspect they will propose.
I also think two astronauts would be streching it. A one-man mission should be feasible though.
Is increased radiation protection somewhere in those numbers, or just fly stock Dragon and see how it goes? FH quoted GTO payload is 12t, going to be tough without some high energy kick stage.
Quote from: rklaehn on 02/23/2013 09:39 am And of course it is a pretty high risk mission.People keep saying this, but why?
A one-man mission should be feasible though.
Quote from: rklaehn on 02/23/2013 09:02 amQuote from: Dalhousie on 02/23/2013 08:49 amQuote from: rklaehn on 02/23/2013 06:42 amI think they will propose to tough it out without any additional living space. There is a limit to how much you can tough it out. Ten cubic m just is not enough for two people over 500 days, not when all the onboard equipment cuts it to half this. Nevertheless that is what I suspect they will propose.If they propose that, then that alone is enough to kill it.
Yes, the person would be lonely. But I suspect that would be better than two people at each others‛ throats after six months.
Quote from: Dalhousie on 02/23/2013 10:23 amQuote from: rklaehn on 02/23/2013 09:02 amNevertheless that is what I suspect they will propose.If they propose that, then that alone is enough to kill it.Why? The only thing that can (and most likely will) kill this mission is a lack of funding. If the likelihood of the crew going insane is high, it will make getting advertising funding more difficult. Except maybe for antidepressants.But assuming that dennis tito has managed to increase his net worth substantially, and is willing to liquidate it all, who's going to stop him?I know that there is a law for everything in the US, but as far as I know engaging in expensive and very dangerous activities is not yet outlawed, except maybe in NYC.
Quote from: DLR on 02/23/2013 10:35 amI also think two astronauts would be streching it. A one-man mission should be feasible though. I was about to say the same thing. Why is everyone assuming a two person crew?A one person mission has half the consumables and twice the volume per person. No risks of interpersonal conflict during the mission either.Yes, the person would be lonely. But I suspect that would be better than two people at each others‛ throats after six months.