Don't the shadowed areas, coldest known in the solar system, mean you can easily use superconducting inductors as nearly perfectly efficient batteries? That'd be a great match for endless sunlight at such an outpost.Tom Ligon wrote: the south pole could be the first settlement site. If they find ice. The poles offer the unique possibility of solar power ... just stick the panels on masts and rotate them to follow the sun. Elsewhere solar is a periodic flop.
Polywell on the Moon?
And shield against the D-D side reactions.Aero wrote:Good point! All you need to do is mine it and refine it. And find the D.KitemanSA wrote:Who needs Boron11? Remember, the moon is the proverbial home of He3. Why not use a DHe3 reaction. Much easier, and still aneutronic. And it produces H as a byproduct! The main argument against the DHe3 fuel cycle (remoteness of fuel source) is kind of gone, no?
Engineering is the art of making what you want from what you can get at a profit.
Bring the D from Earth if needed. Liquid D could be used as a nuclear fuel, then the H ash can be used for water or as a chemical fuel.Aero wrote:Good point! All you need to do is mine it and refine it. And find the D.
Last edited by KitemanSA on Thu Oct 22, 2009 9:24 pm, edited 1 time in total.
Betruger,
The shaded areas at the poles are very cold, but they are so because they receive radiated energy only by starlight and the temperature of deep space. If you put a hot reactor there, it will quickly warm the environment.
A large black plate of aluminum or copper in such a shadowed crater would get very cold and be useful as a heat sink for whatever processes you need to be cold. If you were to place typical superconductors on such a plate they should chill to superconducting temperature or close to it, but any radiative heat source in the vicinity would probably heat them beyond superconducting temperature quickly, based on whatever energy flow balance the radiating plate achieved.
The regolith in the crater is supposedly "fluffy" based on recent observations, and is probably a lousy conductor of heat, so you could not simply sink heat to it.
Bottom line, areas facing deep space are great places for heat radiators, but the spot alone is not sufficient to cool a heat-producer. Even a Polywell will need radiators to operate there. A Polywell would hopefully have the same advantage as a CSR space propulsion system: far less radiator would be needed than a fission steam plant or most other powerplants would require.
The shaded areas at the poles are very cold, but they are so because they receive radiated energy only by starlight and the temperature of deep space. If you put a hot reactor there, it will quickly warm the environment.
A large black plate of aluminum or copper in such a shadowed crater would get very cold and be useful as a heat sink for whatever processes you need to be cold. If you were to place typical superconductors on such a plate they should chill to superconducting temperature or close to it, but any radiative heat source in the vicinity would probably heat them beyond superconducting temperature quickly, based on whatever energy flow balance the radiating plate achieved.
The regolith in the crater is supposedly "fluffy" based on recent observations, and is probably a lousy conductor of heat, so you could not simply sink heat to it.
Bottom line, areas facing deep space are great places for heat radiators, but the spot alone is not sufficient to cool a heat-producer. Even a Polywell will need radiators to operate there. A Polywell would hopefully have the same advantage as a CSR space propulsion system: far less radiator would be needed than a fission steam plant or most other powerplants would require.
I suspect the handling of waste heat on the moon would approach , but perhaps not match the requirements on a space ship. The lunar regolith is a poor thermal conductor so using it to conduct away waste heat would be limited. On the other side of the coin, it would not take much distance/ thickness to insulate a heat producer from the background. At the Apollo 15 site the regolith had a constant temperature of ~ 250 degrees K at a depth of ~ 80 cm during both the day and night.Tom Ligon wrote:Betruger,
The shaded areas at the poles are very cold, but they are so because they receive radiated energy only by starlight and the temperature of deep space. If you put a hot reactor there, it will quickly warm the environment.
A large black plate of aluminum or copper in such a shadowed crater would get very cold and be useful as a heat sink for whatever processes you need to be cold. If you were to place typical superconductors on such a plate they should chill to superconducting temperature or close to it, but any radiative heat source in the vicinity would probably heat them beyond superconducting temperature quickly, based on whatever energy flow balance the radiating plate achieved.
The regolith in the crater is supposedly "fluffy" based on recent observations, and is probably a lousy conductor of heat, so you could not simply sink heat to it.
Bottom line, areas facing deep space are great places for heat radiators, but the spot alone is not sufficient to cool a heat-producer. Even a Polywell will need radiators to operate there. A Polywell would hopefully have the same advantage as a CSR space propulsion system: far less radiator would be needed than a fission steam plant or most other powerplants would require.
http://education.ksc.nasa.gov/esmdspace ... Properties
Concerning KitemanSA's thought of using hydrogen ash from D-He3 fusion as a water supply-
As far as getting useful amounts of hydrogen from D- He3 fusion, you might get a few grams per day if you are generating a lot of power.
Assume 10 ^20 fusions per second generates ~ 100 MW. That would result in perhaps 1x10^20 hydrogens per second, or ~ 1/6000th of a mole. Multiply that by 3600 seconds per hour and 24 hr per day would yield ~ 14 moles of atomic hydrogen per day(14 grams), or 7 moles of molecular hydrogen per day. Incorperated into water would result in 7 moles of water or ~ 130 cc of water. Enough for ~ one 4 oz drink per day.
Dan Tibbets
To error is human... and I'm very human.
Dan, Thanks! That is a very interesting calculation. I assume it is indicative of the other waste products from a Polywell. It says to me, in terms that I can understand, "What you get out of a BFR is ENERGY, and very little else."As far as getting useful amounts of hydrogen from D- He3 fusion, you might get a few grams per day if you are generating a lot of power.
Assume 10 ^20 fusions per second generates ~ 100 MW. That would result in perhaps 1x10^20 hydrogens per second, or ~ 1/6000th of a mole. Multiply that by 3600 seconds per hour and 24 hr per day would yield ~ 14 moles of atomic hydrogen per day(14 grams), or 7 moles of molecular hydrogen per day. Incorperated into water would result in 7 moles of water or ~ 130 cc of water. Enough for ~ one 4 oz drink per day.
Aero
This is just a real crazy thread. IF someone were to say "I REALLY REALLY insist of having a fusion reactor on the moon to make energy", like POTUS whilst (s)he jumps up and down in a tantrum then, excepting that particular scenario, fusion energy is just the flat-out wrong energy technology for moon missions. It'll just never happen. Try considering which is the best technology, rather than which is the best fusion technology, for this particular issue. The question didn't presume to demand to use fusion.
If it works. A direct conversion BFR would probably be the best due to:chrismb wrote:This is just a real crazy thread. IF someone were to say "I REALLY REALLY insist of having a fusion reactor on the moon to make energy", like POTUS whilst (s)he jumps up and down in a tantrum then, excepting that particular scenario, fusion energy is just the flat-out wrong energy technology for moon missions. It'll just never happen. Try considering which is the best technology, rather than which is the best fusion technology, for this particular issue. The question didn't presume to demand to use fusion.
1. Lower heat rejection rqmts.
2. The possibility of rejecting the heat at higher temps.
T^4 is rather powerful.
Engineering is the art of making what you want from what you can get at a profit.
I didn't mean to imply THE water supply, just that 50% of the neglegible mass shipped from Earth in the D supply would be re-usable. It was kind of a way to emphasize the minimal nature of the D supply costs in the first place! Thanks for validating my point.D Tibbets wrote: Concerning KitemanSA's thought of using hydrogen ash from D-He3 fusion as a water supply-
As far as getting useful amounts of hydrogen from D- He3 fusion, you might get a few grams per day if you are generating a lot of power.
Assume 10 ^20 fusions per second generates ~ 100 MW. That would result in perhaps 1x10^20 hydrogens per second, or ~ 1/6000th of a mole. Multiply that by 3600 seconds per hour and 24 hr per day would yield ~ 14 moles of atomic hydrogen per day(14 grams), or 7 moles of molecular hydrogen per day. Incorperated into water would result in 7 moles of water or ~ 130 cc of water. Enough for ~ one 4 oz drink per day.
Oh! OK. Well, in that case... seeing as the solar wind is present AT the moon's surface and seeing how everyone is convinced that this 'direct electrical conversion' mumbo-jumbo is going to work, then why not simply harvest the energy in the solar wind directly? Why bother building a nuclear reactor to generate fast fusion ions when there's a big green one belting the stuff down on you already?KitemanSA wrote:Of course it is! We're all just having fun! Keep up, dude!chrismb wrote:This is just a real crazy thread.
Last edited by chrismb on Thu Oct 22, 2009 10:05 pm, edited 1 time in total.
As long as we are being crazy ...
Solar windmills? Solar sails rotating horizontally?
Somehow I have to believe that direct conversion of solar wind ion flux to electricity is going to be pretty feeble, compared to the power available from conventional solar panels. Even if you could get power that way, it will still be on for two weeks, off for two weeks.
We had a big argument a few weeks back about too much power (ITER plants supposed to be too powerful to use). The same might apply here. If Polywells crank out 100 MW or more, we've got a long way to go before anyone has the need for that kind of power on Luna. We do have off the shelf fission plants that probably scale well. They would need substantial heat radiators, but the lunar environment can tolerate nukes well because the radiation up there is hellish anyway, few NIMBY neighbors to complain, no terrorists to steal the fuel and make bombs, nobody would mind dumping waste down a convenient hole as we can be pretty darned sure there is no groundwater to contaminate.
My profound hope is that we will eventually have working BFRs and the need for that sort of power on the Moon (running cities and industry, making rocket fuel, etc.). I expect the match would be very good.
Solar windmills? Solar sails rotating horizontally?
Somehow I have to believe that direct conversion of solar wind ion flux to electricity is going to be pretty feeble, compared to the power available from conventional solar panels. Even if you could get power that way, it will still be on for two weeks, off for two weeks.
We had a big argument a few weeks back about too much power (ITER plants supposed to be too powerful to use). The same might apply here. If Polywells crank out 100 MW or more, we've got a long way to go before anyone has the need for that kind of power on Luna. We do have off the shelf fission plants that probably scale well. They would need substantial heat radiators, but the lunar environment can tolerate nukes well because the radiation up there is hellish anyway, few NIMBY neighbors to complain, no terrorists to steal the fuel and make bombs, nobody would mind dumping waste down a convenient hole as we can be pretty darned sure there is no groundwater to contaminate.
My profound hope is that we will eventually have working BFRs and the need for that sort of power on the Moon (running cities and industry, making rocket fuel, etc.). I expect the match would be very good.
There is an unfortunate risk that we may have to wait awhile longer.
http://www.msnbc.msn.com/id/33435155/ns ... nce-space/
There are a lot of seemingly good ideas out there that could be easily falsified with a few million dollars. I say, go ahead and prove that they won't work so that the brains attracted to them will be freed to work on other good ideas. And if something happens to work, well, that would be great, too.
http://www.msnbc.msn.com/id/33435155/ns ... nce-space/
Maybe they just need to throw a few $Billion into basic research. ME thrusters come to mind, and the Heim Inertial Drive, too.Presidential panel says NASA should skip moon
Space agency should aim for asteroid or Martian moon instead
By Seth Borenstein
updated 1:31 p.m. CT, Thurs., Oct . 22, 2009
WASHINGTON - NASA needs to make a major detour on its grand plans to return astronauts to the moon, a special independent panel told the White House Thursday.
There are a lot of seemingly good ideas out there that could be easily falsified with a few million dollars. I say, go ahead and prove that they won't work so that the brains attracted to them will be freed to work on other good ideas. And if something happens to work, well, that would be great, too.
Aero
There was a report out a few months ago that showed the Ares/Orion system could reach near Earth asteroids easier than the Moon. The argument should apply to any lunar-capable craft.
The capsule in question could supposedly handle fairly long trips, in the months. Without the need to drop into lunar orbit and deploy a lander, then climb back off the surface, the energy required for NEO rendezvous is easily in reach of such a mission.
I've always thought the Moon was fairly useless. Mars, too. I'm an old L5er, prone to thinking in terms of O'Neill colonies in the asteroid belt as our best bet. We know many asteroids have water.
The capsule in question could supposedly handle fairly long trips, in the months. Without the need to drop into lunar orbit and deploy a lander, then climb back off the surface, the energy required for NEO rendezvous is easily in reach of such a mission.
I've always thought the Moon was fairly useless. Mars, too. I'm an old L5er, prone to thinking in terms of O'Neill colonies in the asteroid belt as our best bet. We know many asteroids have water.