Pardon the large number of "IFs" in this question, but I was wondering:
IF - the BFR works reasonably well, and
IF - NASA does continue the Return to the Moon effort, and
IF - there results a permanent Lunar outpost, then
Is it a forgone conclusion that a BFR (or two for operational reliability) will be the most suitable power source for the Lunar outpost?
Polywell on the Moon?
I expect the first power sources used on Luna will be fairly small thermionic or thermoelectric devices. I believe Russia has the lead in thermionic generators, whereas the US uses thermoelectric sources such as the SNAP generators. These tend to be down in the kW range, but they are small enough to get up there as a piece of the envisioned payloads.
Polywells, as presently envisioned, would be a tight fit on an Ares V. It could haul around 143,000 lbs to the moon, but a reactor something like 6-8 meters in diameter may require a special upper stage. I found one NASA sheet that says the stage is 33 ft in diameter, about 10 meters, so maybe you could just fit one on, but the cargo pod shown was smaller-diameter. I was at KSC last week and stood under the Saturn V ... I think the second stage was a bit on the skinny side.
http://www.nasa.gov/pdf/293938main_Ares ... _nov08.pdf
What would fit, and what I would expect they might try first because of the long operational record, is a fission reactor along the lines of the SL-22 used in Antarctica.
The bigger limit is getting one down to the surface. The link above shows their proposed lander, and it would need to get the reactor down to the surface. I don't think it is up to the job.
But I think a Polywell would be an excellent reactor system for the Moon once it proves its stuff and they can get it there or assemble it there. Polywells need a great vacuum system, and will probably work better in space than on Earth.
Polywells, as presently envisioned, would be a tight fit on an Ares V. It could haul around 143,000 lbs to the moon, but a reactor something like 6-8 meters in diameter may require a special upper stage. I found one NASA sheet that says the stage is 33 ft in diameter, about 10 meters, so maybe you could just fit one on, but the cargo pod shown was smaller-diameter. I was at KSC last week and stood under the Saturn V ... I think the second stage was a bit on the skinny side.
http://www.nasa.gov/pdf/293938main_Ares ... _nov08.pdf
What would fit, and what I would expect they might try first because of the long operational record, is a fission reactor along the lines of the SL-22 used in Antarctica.
The bigger limit is getting one down to the surface. The link above shows their proposed lander, and it would need to get the reactor down to the surface. I don't think it is up to the job.
But I think a Polywell would be an excellent reactor system for the Moon once it proves its stuff and they can get it there or assemble it there. Polywells need a great vacuum system, and will probably work better in space than on Earth.
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kunkmiester
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They'd probably use a fission system, like the trashcan nukes or something like Tom said, and ship a polywell in pieces to be assembled. It probably would work better in space, but I also have to wonder if they wouldn't put pumps on ti anyway to recover helium to feed into the cooling system if needed.
Evil is evil, no matter how small
I was thinking that they could avoid the vacuum chamber on the moon, but if they need to salvage unspent fuel then they would need containment of some sort. Does anyone have an idea about how common Boron and Hydrogen are on the Moon? Of course a few hundred Kilograms of refined boron would probably be cheaper to transport than the equipment it takes to confine and refine it. Maybe later it can be refined locally. Will they want to salvage the reaction product helium? How much will that be and is it worth the cost?
As for recovering the cooling Helium, won't it remain liquid within the cooling plumbing circuits? If so, then using a heat pump it is just a matter of radiating the extracted heat into the shade on the moon. Not necessarily easy, but conceptually simple. Alternatively, maybe an eight meter copper coil set with lower B field strength can be made to work at the achievable low temperatures on the Moon. Such a coil set might be difficult to transport though.
Anyway, it’s beginning to look as though building a BFR for the Moon will include a custom design project. How many units do you suppose they will need? Consider that with excess ground power and a Mach drive available, people, in particular family members may start moving to the Moon long term if not permanently.
As for recovering the cooling Helium, won't it remain liquid within the cooling plumbing circuits? If so, then using a heat pump it is just a matter of radiating the extracted heat into the shade on the moon. Not necessarily easy, but conceptually simple. Alternatively, maybe an eight meter copper coil set with lower B field strength can be made to work at the achievable low temperatures on the Moon. Such a coil set might be difficult to transport though.
Anyway, it’s beginning to look as though building a BFR for the Moon will include a custom design project. How many units do you suppose they will need? Consider that with excess ground power and a Mach drive available, people, in particular family members may start moving to the Moon long term if not permanently.
Aero
There is also the matter of collecting "unburnt" fuel.kunkmiester wrote:They'd probably use a fission system, like the trashcan nukes or something like Tom said, and ship a polywell in pieces to be assembled. It probably would work better in space, but I also have to wonder if they wouldn't put pumps on ti anyway to recover helium to feed into the cooling system if needed.
Engineering is the art of making what you want from what you can get at a profit.
I would agree. It'd have to be proven technology, and fission is proven. In fact, it's so proven and robust, you just need to simply watch 'a lump of the stuff' give off useful heat, whereas all manner of problems can occur in an electronically controlled system with thousands of vulnerable parts. Fission. Definitely. Fusion power just won't have the power density (viz power versus take-off mass) or reliability.kunkmiester wrote:They'd probably use a fission system,
Do you envisage a polar or more equatorial base? Solar panels are the next best thing, but would be off for a continuous fortnight every month. Similarly, if all fails on the 'wrong side' you may really need something that you could fix with a hammer.
If you gave me the plan for the mission, I'd use solar-panelled satellites orbiting the moon, beaming microwaves down to the base, as per Bill Brown's ideas. it'd work a damned sight better on the Moon (with no atmosphere, clouds or poss aircraft getting in the way!) Anyone know the lunar-stationary orbital distance?
Last edited by chrismb on Wed Oct 21, 2009 11:06 pm, edited 3 times in total.
The B11 would condense out. H could be reacted with O and you condense the water out. Electrolyse it and you are back to H.Aero wrote:Will the unspent/unburnt fuel (tow-may-to/tow-ma-toe) be pure once recovered or is there something created in the reactor, from spalling perhaps, that makes the recovered fuel unsuitable for use without refining?
Spallation products may be a problem.
Engineering is the art of making what you want from what you can get at a profit.
NASA is looking for ideas (they just don't have the money to fund them):
"We are now formulating plans for new prize challenges with the help of engineers and scientists throughout NASA - and we would like to consider ideas from private industry, outside organizations and the public as well. Deadline is November 8, 2009."
http://www.nasa.gov/offices/ipp/innovat ... uture.html
I posted one there a while ago:
http://www.nasa.gov/offices/ipp/innovat ... ideas.html
"Fusion Propulsion and Power Challenge"
(I kept the target thresholds low on purpose, figuring that mass to LEO equivalent to 3 or 4 medium-sized cars and available power of 1 watt/lb payload would be good enough for starters.)
"We are now formulating plans for new prize challenges with the help of engineers and scientists throughout NASA - and we would like to consider ideas from private industry, outside organizations and the public as well. Deadline is November 8, 2009."
http://www.nasa.gov/offices/ipp/innovat ... uture.html
I posted one there a while ago:
http://www.nasa.gov/offices/ipp/innovat ... ideas.html
"Fusion Propulsion and Power Challenge"
(I kept the target thresholds low on purpose, figuring that mass to LEO equivalent to 3 or 4 medium-sized cars and available power of 1 watt/lb payload would be good enough for starters.)
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?
Aero
The point about orbiting power satellites has a particular merit in the case of early Moon settlements. As I pointed out, you could probably launch reactors to lunar orbit using Ares V, but landing them would be a trick. So you might well send up powersats of considerable size and mass, and all they would need on the surface would be lightweight rectennae and some diodes.
Depending on how the LCROSS impact results turn out, 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.
If ice is present, or sufficient hydrogen to manufacture water from rocks, enough hydrogen to fuel a p-B11 system is a cinch. The problem is water for living ... if you have enough of that you have the fusion fuel source covered.
Boron should be there, just not in borax beds ... no water processes to extract it. I think they did find it on Mars.
Deuterium is a bit of a trick. In principle, one atom in 6000 of hydrogen is deuterium, and again, if there is enough water, you can find some deuterium for fuel. We'll happily drink the other 5999 atoms. My wonder is, if the hydrogen is from solar wind, is it depleted in deuterium. Stars burn deuterium so quickly it is essentially gone as soon as they form. And yet, they expect He3 in the regolith from solar wind! He3 should burn about as fast. Stars do make deuterium, He3, and tritium (which would decay to He3), but these should be gone in a trice. Anyway, where there is He3 there should be comparable amounts of deuterium, I would think.
Depending on how the LCROSS impact results turn out, 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.
If ice is present, or sufficient hydrogen to manufacture water from rocks, enough hydrogen to fuel a p-B11 system is a cinch. The problem is water for living ... if you have enough of that you have the fusion fuel source covered.
Boron should be there, just not in borax beds ... no water processes to extract it. I think they did find it on Mars.
Deuterium is a bit of a trick. In principle, one atom in 6000 of hydrogen is deuterium, and again, if there is enough water, you can find some deuterium for fuel. We'll happily drink the other 5999 atoms. My wonder is, if the hydrogen is from solar wind, is it depleted in deuterium. Stars burn deuterium so quickly it is essentially gone as soon as they form. And yet, they expect He3 in the regolith from solar wind! He3 should burn about as fast. Stars do make deuterium, He3, and tritium (which would decay to He3), but these should be gone in a trice. Anyway, where there is He3 there should be comparable amounts of deuterium, I would think.
Ares V looks dead after the Augustine report. Even Ares I might die if the Falcon 9 Dragon can be man rated in short order. I have no pity for NASA choosing yet another platinum-plated boondoggle over functionality. DIRECT is the design philosophy they should've embraced, much like Mars Direct vs the 3-5x more expensive NASA Design Reference Missions or the humungo-budget "90 day study" of 1989.Tom Ligon wrote:Polywells, as presently envisioned, would be a tight fit on an Ares V. It could haul around 143,000 lbs to the moon, but a reactor something like 6-8 meters in diameter may require a special upper stage. I found one NASA sheet that says the stage is 33 ft in diameter, about 10 meters, so maybe you could just fit one on, but the cargo pod shown was smaller-diameter. I was at KSC last week and stood under the Saturn V ... I think the second stage was a bit on the skinny side.
http://www.nasa.gov/pdf/293938main_Ares ... _nov08.pdf
Deliver it in modular segments and assemble on-site. Alternatively build Dr Bussard's LEO-L shuttle in LEO, set the thing down on the surface of the Moon and have it never take off again. Send the QED rocket sans polywell reactor and chassis back as cargo on another LEO-L shuttle if desired.Tom Ligon wrote:The bigger limit is getting one down to the surface. The link above shows their proposed lander, and it would need to get the reactor down to the surface. I don't think it is up to the job.
Last edited by djolds1 on Thu Oct 22, 2009 4:23 am, edited 1 time in total.
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