In article ,
nafod40 wrote:
We could send up water, then just let solar array-powered electrolysis
slowly do its magic to make the fuel. Two years for a bag of fuel? No
problem, no rush.

Such schemes have been looked at repeatedly, but unfortunately they tend
to require inordinately large amounts of power. Water electrolysis needs
roughly 10kW-hr/kg, and that is a *lot* of power by space standards.

Electrolyzing 80t of water -- enough fuel for an Apollo-sized lunar
mission, nowhere near enough for a Mars expedition -- in a year requires
90kW of continuous power. (Nearly double that if your electrolysis plant
runs only when the station is in sunlight.) The full continuous design
power of ISS when completed, assuming no further major Russian
contributions, is under 80kW, and nearly half of that is required for
station systems.

That way no volatile components in the launch. You could freeze the
water, and use it as part of the structure of the launch vehicle to
reduce weight.

Ice is not a good structural material, unfortunately.

Alternate launch techniques such as rail guns? The
payload would certainly tolerate the G's.

So would most any liquid fuel.
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MOST launched 30 June; science observations running | Henry Spencer
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