The Moon Society Forum

What do people think of fuel depots, in Terran, Lunar, and Martian orbit? They would make single stage vehicles between them a practical proposition, as each craft would only have a delta-V requirement of max. 4km/s. At Luna, I imagine fuel would be Al/LOX monoprop; at Mars, something produced from its moons. But what about Terra?

Earth has the deepest gravity well, yes, but it is also home to the greatest amount of traffic (for the forseeable future, at least). I think that a fuel depot in earth orbit is a virtual necessity for a spacefaring civilization. It makes interplanetary traffic possible with (proposed) single-stage-to-orbit vehicles. If each SSTO mission topped its tanks off with extra LH2 to the limit of its spare mass fraction, and offloaded that hydrogen in orbit, soon there would be a sufficient stock to supply a lunar or interplanetary voyage. Earth hydrogen could be transported to the Moon, and plentiful lunar oxygen could be returned on the backhaul. Orbital fuel depots are a great idea.

Edit To Add: If your question is in regards to which fuel should be stockpiled, my answer is the same. Hydrogen, most definitely. It is at the same time the chemical propellant with the highest specific impulse and efficiency and an absolute necessity for the growth of artificial biospheres. Its light weight also gives it the most "bang for the buck" when being lifted out of Earth's gravity well. Lift as much hydrogen as possible from Earth; let the oxygen come from the Moon.

First post and I see that another member from NewMars is here in one Terraformer....

Yes hydrogen is the biggest bang for the buck but with cryrogenic boiloff a problem for longevity of the fuels being available I wonder if sending up water is a better way to handle storage long term.

Well off to read some more new posts....

Why Hydrogen? Methane has a lower Isp, yes, but it is much easier to store, and contains Carbon as well, an absolute must for biospheres. Oxygen on it's own can be used in a solar thermal rocket, and I imagine that it will be what is used to transport Oxygen to LEO. Aluminum is available on LUna, and mixed with Oxygen makes a reasonably good (270-280s) propellent. Given it's density, it's enough to fuel single stage vehicles going to Luna, Mars, Venus etc.

The new nasa budget proposal from monday lists 7.8 billion over the next five years for large scale, new approaches to space flight including on-orbit refueling. hooraaay

http://www.nasa.gov/pdf/420990main_FY_2 ... b_2010.pdf
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