AntiKev - 20/2/2007 11:25 AMI don't know that it's ever been considered. What is more likely is shipping water to the facility, and then using solar power to perform electrolysis on orbit. Basically make the propellant on demand, or two to three days prior to the customer's arrival, and then condense it. Since you have the condensation facilities on board, you can actually re-condense the boil-off, mitigating the concern.
Marcus - 20/2/2007 2:36 PMIs the L-2 point in the Earth's shadow or is it too small (in terms of degrees occluded) at that distance to eclipse the sun? That far away, the infrared radiation from earth should be infintesimal. Unfortunately, I bet the % of the solar disc occluded is also infinitesimal.
sandrot - 20/2/2007 4:23 PMQuoteMarcus - 20/2/2007 2:36 PMIs the L-2 point in the Earth's shadow or is it too small (in terms of degrees occluded) at that distance to eclipse the sun? That far away, the infrared radiation from earth should be infintesimal. Unfortunately, I bet the % of the solar disc occluded is also infinitesimal. I am talking of a solar shade attached or very close to the fuel depot, as it happens on JWST. BTW the sun shade for JWST is layered, I wonder what is it made of?
Jim - 20/2/2007 4:28 PMMylar
Bill White - 20/2/2007 8:30 PMBoil off is a good reason, IMHO, to strongly consider LOX & CH4 rather than LOX and LH2 for on orbit propellant depots.LOX and kerosene? Largely avoiding cryogenic issues at least for the kerosene could save infrastructure costs traded against lower ISP.
Jim - 20/2/2007 7:52 PMQuoteBill White - 20/2/2007 8:30 PMBoil off is a good reason, IMHO, to strongly consider LOX & CH4 rather than LOX and LH2 for on orbit propellant depots.LOX and kerosene? Largely avoiding cryogenic issues at least for the kerosene could save infrastructure costs traded against lower ISP.Cryogens have a natural pumping mechanism. RP-1 would require high pressure gases and/or compressors
sandrot - 20/2/2007 10:10 PMI was further reading about this JWST sun shade. Thanks to it instrumentation can reach temperatures of 30 to 50 K.So it seems the same sun shade concept can be good for LOX, I don't know for LH2 unless the tank can withstand increased pressures.For your curiosity:http://www.stsci.edu/jwst/overview/design/sunshade.html
sandrot - 20/2/2007 9:19 AMHas a sun shade (similar to JWST's) ever been considered to reduce propellant boil-off in an orbital propellant depot?
Is the L-2 point in the Earth's shadow or is it too small (in terms of degrees occluded) at that distance to eclipse the sun? That far away, the infrared radiation from earth should be infintesimal. Unfortunately, I bet the % of the solar disc occluded is also infinitesimal. QuoteThe penumbra of Earth's shadow is about 13000km in diameter. Space telescopes planning to go there can avoid hitting it for six years, and then it's a 15m/s maneuver to avoid hitting it. Lissajous orbits at L2 are about million km in diameter.
The penumbra of Earth's shadow is about 13000km in diameter. Space telescopes planning to go there can avoid hitting it for six years, and then it's a 15m/s maneuver to avoid hitting it. Lissajous orbits at L2 are about million km in diameter.