Former Senator Wants to Mine The Moon

MarkWhittington writes "Harrison Schmitt, Apollo Moonwalker, geologist, and former United States Senator, recently presented a plan to solve the world's long term energy problems by developing fusion power fueled with helium-3 mined from the Moon. He presented this plan in a speech at Williston Basin Petroleum Conference."

Comments

Why is this notable?

[artor3]

We've known for ages that helium-3 is a good potential fusion fuel, and that mining the moon could be a good source of it. But we don't have fusion power plants yet, nor are we particularly close to getting them. So why talking about mining fuel that we're at least twenty years away from being able to use?

Re:Why is this notable?

[SharpFang]

...because it's at least 20 years until the mining operation will be possible to start.

Also, think of all the nice things we got as a total by-product of the space race. Helium-3 is the tip of an iceberg. Permanent moon base, self-sustainable spacecraft to travel earth-moon on routine route, possibly fusion spacecraft propulsion, humans not only getting to the moon but going there routinely, experience in space mining in general (asteroid belt anyone?) and generally a significant leap towards making space travel easy and common.

It doesn't even have to be really profitable. It would be nice if the helium-3 deposits paid for the investment, but it's all the tech developed to get this to work, where all the REAL profit would happen.

Re:Why is this notable?

[X0563511]

Well, don't forget that the world is running out of helium as it is. Even if fusion fizzles, having a source of the stuff in hand is better than not.

Do you realize how many hi-tech things need helium at some point in their creation or use?

You do like being able to get an MRI, for example?

Re:Why is this notable?

[RsG]

...because it's at least 20 years until the mining operation will be possible to start.

Actually, that's pretty pessimistic.

The last time we went to the moon, it took around twelve years of R&D, using tech that's positively antiquated by modern standards, and with no precedent whatsoever to show that it was even possible to send a person to the moon and bring them back alive.

If we were to repeat that process now, we'd have the advantage of automation, precedent and over half a century of R&D to start with. And since we're talking about a mining operation, we could remove the human factor altogether, and rely on teleoperated machines (granted there's that three second delay to contend with, but there are workarounds). The total amount of He-3 fuel needed to make the trip worthwhile is small, and an unmanned return vehicle could use methods not suitable to human spaceflight.

Not that I wouldn't like to see more work on manned spaceflight mind you, but I think you're overestimating the amount of infrastructure needed for this kind of work.

Re:Why is this notable?

[The Wooden Badger]

The Chinese could do it in 10? I hope that doesn't turn out like their high speed trains.

Re:Why is this notable?

[TheTurtlesMoves]

Lets run some numbers.

He3+He3 gives 12.9MeV of energy per reaction. Thus 1 mol gives 619GJ, or 206 GJ per gram. Assume 1.5 GW power station would produce an average of 1GW all year. That is 31.5e15 J for the year. Assume a 50% efficiency and we need 306 kg of He3 per year. At STP that is about 2000 cubic meters of He3. Now in the Luna surface He3 is only at .01ppm. So at 100% mining efficiency we need to process 30 million tons of rock. In reality you would be very lucky to get 50% efficiency and you still need to consider how much of that He3 you need to burn to run the mining operation. So it is probably closer to 60-100million tons of Luna rock per year.

And thats for just one power station.

Now lets consider the fact that D+T fusion is not here yet and that He3 fusion is more than a 1000 times harder to do. In fact if you can run a He3 fusion plant you can run a DD fusion plant for a fraction of the cost since it is more that 10 times easier to do. Also the ash from DD is He3! It would be cheaper to have DD fusion He3 breeder reactors, than to mine the moon.

He3 is something moon fans bring up since they can't think of any other reason to go there.

Re:Why is this notable?

[rgbatduke]

This is a slight exaggeration and subject to unrealistic assumptions. Read (for example) http://en.wikipedia.org/wiki/Helium-3#Fusion_reactions -- at reasonable efficiencies, it would require close to 80 kg of fuel to run a 1/2 GW power plant, "hand held" only if you are a pretty strong person. To provide all the electricity required to fuel all the homes in the US it would require roughly 20 tons of He3 a year. To replace ALL energy sources used by the US would require roughly 25 times that, some 500 tons a year. If we pretend they are metric tons to make the arithmetic easy, that's 5x10^5 kg, where the bare "cost" of getting off the moon is roughly 3 x 10^6 J/kg, the actual cost again many times that. And these numbers all assume that we have significantly passed break even in the fusion reaction itself, something that we currently haven't done -- if the best we can do in fusion efficiency is 10%, multiply all of these numbers by 10 (for example). Suddenly our 1 GW power plant requires 1600 kg of fuel and no, you can't carry it around.

Abundant energy on the moon is no problem -- both solar and hypothetical He3 burning give you ELECTRICITY, but electricity is nearly useless for lifting spacecraft in all models except Heinlein's imaginary mass drivers. So we either have to lift real chemical fuels from the Earth to the moon to be able to ship the stuff back or tackle an enormous engineering task on the moon -- no simple "drop a bunch of He3 scavenging robots" but building a mass driving linear accelerator long enough to accelerate payloads to 2.38 km/sec (2.8x10^ Joules/kg). Suddenly we're spending a small fortune on energy to lift the fuel back to earth. Paradoxically, if we burn hydrogen and oxygen as reaction/rocket fuel to lift it back, we will be wasting more fusion energy in the rocket fuel required to lift it back than we are gaining by lifting it.

What was that? Wasting more fusion energy than we gain? The problem is this: If we can burn He3, we can damn well burn D-D and D-T. One hydrogen atom in 6400 is Deuterium right here on Earth. One ninth of the mass of the oceans is hydrogen. Concentrating Deuterium in water (making "heavy water") is straightforward, 70 year old technology and is still done for certain nuclear power plants because it makes a better moderator than ordinary water -- it is economic to do, in other words, in spite of the fact that it isn't even a fuel (there is more energy available by perhaps and order of magnitude in the moderator than in the fission fuel load of a plant that does this, if D-D fusion were efficient at all). The ocean has a mass of 1.4x10^21 kg, or 2.4x10^16 kg of Deuterium. Allowing for higher efficiencies (it requires a higher temperature and pressure to burn He3 because of its greater charge, so it is basically certain that D-D fusion will always be more efficient than He3-anything) but lower yield per reaction as a wash, we might burn as much as 2500 metric tons worldwide per year, but let's be lavish and assume 10,000 (or 10^7 kg). That means there is enough Deuterium in the oceans to fuel world civilization at a significantly higher per capita energy consumption than we now have for a few billion years -- at least a billion before the concentration of D in the ocean is even close to being halved.

So actually, lunar mining of He3 isn't just stupid, it is insanely, massively, stupendously stupid. It is a thinly veiled attempt by a former astronaut to try to keep the enormously expensive space program funded by inventing the most vaporous of vaporware -- the illusion of cheap energy from the moon!

Of course, anyone who has actually read Heinlein knows that the same mass drivers that deliver our fuel in metric ton payloads could deliver e.g. 1 metric ton rocks instead. 1 metric ton of rock hitting the Earth at escape speed is 6x10^10 Joules of heat all released in a second at a single point of impac

A little premature.

[Sitnalta]

Shouldn't we... I dunno... invent sustainable fusion first? It's kinda like buying the cart before the horse. If the cart was three hundred thousand kilometers in space.