Reply To: Look at this

[Arvid]

Aeronaut wrote: Besides, that kind of mobility will open up the space travel and vacation industries. Been waiting for that all my life.

First, belated congratulations on your 1000th post. Yeah, I’ve been waiting for that my whole life too. I was 17 (well, almost) when we landed on the moon for the first time. Now I’m 58, and we’re farther from being able to land on the moon than we were in 1961. Our only sign of movement is SpaceX reinventing the wheel and taking us back to 1960—and that’s considered progress!

I did a little ballpark arithmetic on my plan—if you had a 1000-tonne spacecraft powered with a D-D reactor, only using the proton for thrust, you’d need about 16 tonnes of deuterium to transport several hundred tonnes of payload from low earth orbit to low mars orbit and back, and in the process produce about 12 tonnes of helium-3 (well, 6—you’d have to wait for the 6 tonnes of tritium to decay). That should be enough to produce (with some added deuterium) about 200 GW-years of electricity. That’s got to be worth something on the open market.

As always, getting rid of waste heat is the real problem. If you took two years for each leg of powered flight, you’d need at least 40 acres of radiators, and there goes your payload. Maybe you could take longer—I’m assuming this is cargo-only, people would have to go much faster because of the cosmic ray exposure. It would be one way of making space travel pay for itself. You’d need to build essentially this interplanetary spacecraft even if you were parking it in orbit to burn deuterium into helium-3. You’d have to use some of that thrust for stationkeeping. Why not go somewhere with it?