4 ms·

I think he's not de-hydrolyzing water to get energy per se, but to generate thrust. Say, you've got a nuclear reactor (or whatever else is more practical) on a

by kolinko 14y ago

I think he's not de-hydrolyzing water to get energy per se, but to generate thrust. Say, you've got a nuclear reactor (or whatever else is more practical) on an asteroid. You cannot use the energy from the reactor to propel the rock, you need to generate thrust. So you take water, you split hydrogen & oxygen, you burn it, you get thrust.

pjscott 14y ago
If you're already bringing a nuclear reactor into space, you could use it to heat up the hydrogen and use it as propellant directly, for more efficient travel. (In situations where you need bursts of high thrust and are willing to sacrifice efficiency, you can also go with a hybrid system that uses both nuclear heat and combustion.) Oh, and fun safety fact: a nuclear reactor isn't actually particularly radioactive until it's turned on. If you launch it out of Earth's orbit before turning it on, you're sitting pretty.
- Tuna-Fish 14y ago
  Also, assuming a lot of electricity, some form of ion engines would likely be (much) more efficient than heating. Also, nuclear reactors aren't the ideal way to make electricity in space. Proper nuclear reactors work as heaters for a heat engine, and heat sinks are proportionally much more expensive in space than on earth. However, solar power is much more efficient. You get 100% efficiency all the time, and it's 30% better in space (near Earth) than it is down here at best. Also, since no structure has to carry any significant weight, you can build things like a flexible paper-thin sheet of solar cells printed on plastic that is spun about it's axis to keep it deployed and spread out.
ChuckMcM 14y ago
Yeah, or just heat the water into steam and shoot it that way, saves a lot of work. There was an interesting paper done on turning a comet off course by basically throwing a supercritical mass of uranium at it. If you can set it up with a 'cool' side (perhaps leading non-metal penetrator cover) and a 'hot' side (the fissioning core) then the thing tries to dig into the comet by vaporizing ice at the back and shoving it out the hole that it made when it went in. Poof, instant rocket engine changing the orbit of the comet (hopefully in a good way)
jonmrodriguez 14y ago
Makes sense. Thanks.

by kolinko 14y ago

pjscott 14y ago

If you're already bringing a nuclear reactor into space, you could use it to heat up the hydrogen and use it as propellant directly, for more efficient travel. (In situations where you need bursts of high thrust and are willing to sacrifice efficiency, you can also go with a hybrid system that uses both nuclear heat and combustion.) Oh, and fun safety fact: a nuclear reactor isn't actually particularly radioactive until it's turned on. If you launch it out of Earth's orbit before turning it on, you're sitting pretty.

Tuna-Fish 14y ago
Also, assuming a lot of electricity, some form of ion engines would likely be (much) more efficient than heating. Also, nuclear reactors aren't the ideal way to make electricity in space. Proper nuclear reactors work as heaters for a heat engine, and heat sinks are proportionally much more expensive in space than on earth. However, solar power is much more efficient. You get 100% efficiency all the time, and it's 30% better in space (near Earth) than it is down here at best. Also, since no structure has to carry any significant weight, you can build things like a flexible paper-thin sheet of solar cells printed on plastic that is spun about it's axis to keep it deployed and spread out.

ChuckMcM 14y ago

Yeah, or just heat the water into steam and shoot it that way, saves a lot of work. There was an interesting paper done on turning a comet off course by basically throwing a supercritical mass of uranium at it. If you can set it up with a 'cool' side (perhaps leading non-metal penetrator cover) and a 'hot' side (the fissioning core) then the thing tries to dig into the comet by vaporizing ice at the back and shoving it out the hole that it made when it went in. Poof, instant rocket engine changing the orbit of the comet (hopefully in a good way)

jonmrodriguez 14y ago

Makes sense. Thanks.