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by tscs37 2905 days ago
We tried many approaches.

Nuclear has amazing power ratios but detonating a nuclear warhead to get moving is somewhat of a problem when you're close to earth.

Fission Heat Engines are quite good but not good enough for takeoff. Ion engines suffer the same fate.

Almost no alternative propulsion method can replace takeoff boosters, thusly limiting the mass you can put into space. With limited mass you can only make engines that big. Or bigger if you assemble them in space which opens other cans of worms.

2 comments

> Nuclear has amazing power ratios but detonating a nuclear warhead to get moving is somewhat of a problem when you're close to earth.

It's not really a 'near earth' issue. Fallout concerns can probably be mitigated (and Freeman Dyson came up with a few ideas in that direction). Research in this direction, however, got killed as part of the various test ban treaties.

From the perspective of trying to reduce any country's desire for having a nuclear bomb program, Project Orion, and other nuclear solutions, is a no go. So even if you were to promise "We'll only start the nuclear component when we hit the moon" the proliferation concerns would still kill NASA's interest in pursuing it.

So yeah; it's not really a technical issue at it's core (though you definitely have technical issues to solve), but rather a political one (which certainly doesn't invalidate it).

Nuclear rockets do not have to be about detonating nuclear warheads. Nuclear thermal rockets have no detonation, no fallout and no wide-scale meltdown risk. They've been demonstrated[1] to have efficiencies 3-4x greater than conventional engines without sacrificing thrust.

[1] https://en.wikipedia.org/wiki/Project_Timberwind