Cost of SSTO Hydrogen Tanker Rockets

In one option for the single-stage-to-the-moon scenario, we use unmanned rockets to deliver hydrogen fuel to the moon. These rockets are launched from Earth. The hydrogen they carry refuels passenger ships on the moon.

The refueling infrastructure for lunar passenger spacecraft will be relatively low, compared with other launch costs. Five primary drivers affect the cost of these rockets:

1. The rockets are about as simple as they can possibly be; no payload except the rocket itself. No passenger stuff, no life support, no abort stuff, no hatches, no doors, no fiddly bits. The only special requirements are things like tank vents and pressure guages, which we'll need no matter how we transport the hydrogen fuel.

2. No worry over mission duration except boil-off. We might be able to use a slow-boat orbit to save delta-V, and hence improve our mass ratio by quite a bit. (I'm not so sure about this one; what we save in delta-V might be lost to boil-off if we ship cryogenic hydrogen. Maybe we can get a double benefit and ship LPG and split it on the moon.)

3. These rockets don't need the redundancy or safety required for people-carrying spacecraft.

4. The tanks, plumbing, pumps, electronics, and maybe even the rocket engines can be used on the moon, so even the used-up core of the rocket is a big economic advantage to the lunar community.

5. The great majority of development cost for the tanker will already be borne in the development of the passenger ship.