EDIT:And even if you brought it back to EML1/2, it's still at a Lagrange point and we only have infrastructure in LEO (besides, the radiation picture is probably actually worse at EML2 than at LMO). If you're reusing the lander but have to refurbish it extensively before reuse, it may well be cheaper just to launch a new one. Otherwise, you could refurbish it at LMO, possibly. Reuse without refurbish is doubly good because you don't have to haul it anywhere and you don't need to fund a refurbish mission.
Isn't the presence of CHON on Phobos and Deimos a given? It might not be, but that's what I vaguely recall. But it could be a while before we were able to extract those. Brute force oxygen from regolith with nuclear power might be a good first step.And Ceres is a colossal reservoir of water. Imagine bringing propellant from the edge of the inner solar system back inwards to Phobos... That of course lies far in the future.
Quote from: MP99 on 04/26/2010 05:32 pmAIUI, the CEV is carried passively until it undocks from the MTV and performs Earth re-entry. Therefore, the SM is discarded before CEV docks with the MTV.That has never been the plan. SM stays on the CM until after MTV undocking, both to protect the TPS and to provide maneuvering capability post-undocking. The plan you describe would require the MTV to be on a entry trajectory prior to CM undocking, then the MTV would have to maneuver to avoid re-entry.
AIUI, the CEV is carried passively until it undocks from the MTV and performs Earth re-entry. Therefore, the SM is discarded before CEV docks with the MTV.
It was not within the scope of the DRA 5.0 activity to recommend specific design upgrades for the Orion vehicle or to develop an upgrade strategy. Instead, a mass estimate of 10 t was used for the vehicle CM to size propulsion stages. An additional 4 t was book-kept for a service module that may be needed to perform an Earth-targeting burn.
...I haven't looked into the plane changes enough to make a reasonable estimate. The difference in inclination is small enough (would lead to ~500m/s delta-v IIRC), but it's the RAAN I know nothing about just yet. I have a link to a table of perturbed orbital elements for the planets somewhere, but I haven't got round to it yet....
Why not have it brake into L1/L2/SEL-2 propulsively?
Quote from: mmeijeri on 04/26/2010 06:07 pmWhy not have it brake into L1/L2/SEL-2 propulsively? My personal thoughts are for a SEP or NEP powered mission departing from and returning to EML-2, under power all the way, both ways. By the time the MTV approaches EML-2 on the return trip, propulsively breaking most of the way in, enough delta-V will have been shed to make capture no more dramatic than a docking event at ISS.
Quote from: mmeijeri on 04/30/2010 02:07 pmThat does not apply to propellant supply flights and you know itIt does apply. A rendezvous and a transfer is a rendezvous and a transfer, no matter what the cargo.
That does not apply to propellant supply flights and you know it
One consideration that has been mentioned is explosion risk. How easy it would be to shield against that? Wouldn't the shrapnel be launched at low velocities compared to orbital velocities? If so it might help to enclose a depot in an unpressurised inflatable shelter capable of absorbing most of the shrapnel.
Has there been any analysis of crew-tended depots? I ask because of the concern about the low level of confidence in uncrewed rendezvous and docking operations.Consider an architecture where a crew is launched to the depot, inhabits a small (maybe Harmony-sized) node, and awaits the arrival of propellant transfer vehicles from any number of suppliers -- as many as can get their vehicle to the depot during the crew's window of availability. In a two-week stay, a crew could oversee half a dozen dockings, transfers and undockings.I'm imagining the habitable node's power needs could be supported by small solar arrays and large battery arrays, since it might be inhabited only 10% of the time.Of course similarly "tended" operations could be used for on-orbit exploration vehicle assembly too....
I think one of the useful prerequisites to propellant depots will be automated docking.
Needing it manned limits you to LEO for the for seeable future.