Am reposting the ~50 day route back to the moon but as attached image.
Quote from: Hop_David on 06/01/2014 09:01 pmAm reposting the ~50 day route back to the moon but as attached image.I love images like these; thanks for reposting them!Does your software have the ability to show the pellet trajectories in a rotating frame of reference where both the Earth and Moon appear fixed? I understand a rotating frame is strange, and I won't try here to justify its use, but note it is used in e.g. the Farquhar route shown in your previous post....
Quote from: savuporo on 05/30/2014 08:12 pmQuote from: muomega0 on 05/30/2014 07:41 pmThe ULA depot adds a conical sunshield to the transfer stage, which brings these rates down an order of magnitude, perhaps 0.1%/day for LH2 away from LEO....Its not just about boil off, long duration loiter for Centaur involves multiple other adjustments that need to be made, including things like batteries.That's part of what the whole Integrated Vehicle Fluids project is about. It replaces the batteries, the hydrazine thrusters (used for settling and ACS), and the helium pressurization (for repressurizing the tanks prior to a burn) with their IVF system. It taps boiled-off GOX/GH2 from the tanks to run a small internal combustion engine, which recharges the batteries, and runs a compressor for boosting the pressure of the GOX/GH2 prior to warming it for autogenous pressurization. With IVF you can run the stage as long as there is LOX and LH2 left in the tank. They had a lot of the prototype hardware for it at the Space Symposium. It's looking like they were going to fly part of it in 2015, and the rest of it in I think 2016. Once it's there, the duration of Centaur goes way up, the dry weight goes down quite a bit, and refuelability becomes easier since you're just dealing with two fluids.Combine that with the improved insulation (MLI or a sun-shield), and using the rotational settling, and there's no reason you couldn't handle months-long missions.~Jon
Quote from: muomega0 on 05/30/2014 07:41 pmThe ULA depot adds a conical sunshield to the transfer stage, which brings these rates down an order of magnitude, perhaps 0.1%/day for LH2 away from LEO....Its not just about boil off, long duration loiter for Centaur involves multiple other adjustments that need to be made, including things like batteries.
The ULA depot adds a conical sunshield to the transfer stage, which brings these rates down an order of magnitude, perhaps 0.1%/day for LH2 away from LEO....
Then I read Jon Goff's comments that boil of could be mitigated -- he seemed to be talking about the same techniques that Goff, Zegler, Kutter and Bar have written about in their propellent depot papers.