UncleMatt wrote:I am wondering why no one has brought up Helium3? It is VERY scare on earth, yet it is all over the moon in quantities that could serve as fuel for fusion reactors for many thousands of years. THAT is where the value is with regard to harvestable resources on the moon, not in gold bars or platinum.
Probably because it doesn't help as much as advertised. You still have the D-D side reaction and Polywell may be adequate for burning D-D.
Of course if you have to go the tokamak route He3 may be essential if H3 production doesn't work out.
Engineering is the art of making what you want from what you can get at a profit.
pfrit wrote:
It would be cheaper to harvest He3 on Earth (not cheap) but no one has a profitable use for it yet.
Oh, it has many uses, being even lower in boiling point than He4. It's a right little wierd isotope around absolute zero. No real practical purpose, agreed, but plenty of scientific purposes.
He-3 does exist on (in) earth, but is far far too rare. Instead it is manufactured. Firstly you make tritium by neutron bombardment of various light elements, then you get He-3 when the tritium decays. So it's at least as rare as T, and then you've got to 'wait' for it for about as long as it takes to mature a decent malt whisky!
It's still very rare on the moon as well, of course. Easier to make it, especially if one is already running DT reactors.
UncleMatt wrote:I am wondering why no one has brought up Helium3? It is VERY scare on earth, yet it is all over the moon in quantities that could serve as fuel for fusion reactors for many thousands of years. THAT is where the value is with regard to harvestable resources on the moon, not in gold bars or platinum.
Seems you didn't actually read the posts in this topic. The eleventh post in specific. The one wherein
I 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?
UncleMatt wrote:I am wondering why no one has brought up Helium3? It is VERY scare on earth, yet it is all over the moon in quantities that could serve as fuel for fusion reactors for many thousands of years. THAT is where the value is with regard to harvestable resources on the moon, not in gold bars or platinum.
Seems you didn't actually read the posts in this topic. The eleventh post in specific. The one wherein
I 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?
Yes, I saw it, but no one was talking about it, so I brought it up again.
UncleMatt wrote: Yes, I saw it, but no one was talking about it, so I brought it up again.
Interesting choice of opening sentance for that situation.
You wrote:I am wondering why no one has brought up Helium3?
Emphasis added.
Gee, care to split a few more semantical hairs? Or can we get back to the topic now? So very sorry I didn't pay more attention to your post than I did.
It'll probably be easier to get Polywell or another PB11 reactor running than develop the infrastructure to get He3. Going to the moon is very expensive, and you really don't need it for He3 anyway. The He3 on the moon is from the solar wind, and a large collector array in orbit to catch it and concentrate it to be shipped home will probably take a bit less investment than strip mining the moon.
Remember, you pretty much have to strip mine the moon to get significant amounts of He3. This will require quite a bit of machinery. Maybe not as much as earth-side strip mining, but still a lot. You either need to build a factory to build the machines, or build them, launch them, and then get them down safely. A collector in orbit would be much cheaper, even with the large surface area needed to be practical.
kunkmiester wrote: A collector in orbit would be much cheaper, even with the large surface area needed to be practical.
Colleectors in Earth orbit are expected to be in GEOsynchronous orbit. Where would you put the one around the Moon? Is there a Sele-synchronous orbit? I don't think so. Which would leave the L! on one side and L2 on the other. Not a lot of space for synchronous collectors. And if they are non-synch you need, what, 6 times ans many?
A 1Mw Polywell with a 17T field would fit into a small rocket. Seems the easy way to go to me.
I was pointing out the silliness of mining He3 on the moon to send to earth. collectors in orbit, regardless of what kind and how many, would make much more sense for collecting He3 than mining it on the moon. A reactor on the moon could indeed run on an He3 reaction, you don't have to mess with lifting it out of a gravity well to get it to your reactor, after all.
And I was assuming an earth orbit, not a lunar one. I thought that would be obvious.
10,000 tons of platinum? What would that do to the price of platinum?
Let's see, platinum goes for about $1360/oz right now (http://www.kitco.com/charts/liveplatinum.html). At 28.35 grams per ounce, that's $47.97 per gram. That's $47,970,000 per tonne. Wikipedia tells me that 239 tonnes of platinum were sold in 2006, so that would be a value of about $11.9 billion per year in the global platinum trade.
How do you get the ore to the ground? I don't think you can refine it out there.
It's currently usually a byproduct. I'd be amazed if you could find 1% ore. I'd be even more amazed if the cost to slow down your 100 * 10,000 = 1 million ton asteroid so it doesn't destroy half a continent isn't prohibitive.
No one wants to see this headline: "BILLIONS DIE IN MINING ACCIDENT"
kunkmiester wrote: And I was assuming an earth orbit, not a lunar one. I thought that would be obvious.
No, sorry, it wasn't, given that the topic is titled "Polywell on the Moon?". Oh well. Assuming Polywell on the Earth, I agree with your statements 100%.
TallDave wrote: How do you get the ore to the ground? I don't think you can refine it out there.
A great trilogy (the "Rosinante" series by Gilliland) points out that once one is out in solar orbit (astreoids, remember), the possiblity of zone refining of mixed metals becomes fairly easy (constant, highly focusable, sunlight). Zone refine the megatonnes of iron to winnow out the ~1% of valuable metals at the high and low melting point ends, and ship the high value metals.
TallDave wrote: How do you get the ore to the ground? I don't think you can refine it out there.
A great trilogy (the "Rosinante" series by Gilliland) points out that once one is out in solar orbit (astreoids, remember), the possiblity of zone refining of mixed metals becomes fairly easy (constant, highly focusable, sunlight). Zone refine the megatonnes of iron to winnow out the ~1% of valuable metals at the high and low melting point ends, and ship the high value metals.
Excellent story too!
You know I worry about people polluting the clean vacuum of space. How will we be able to restore it to the conditions that existed before the dirty pollution was injected into the clean vacuum?
Engineering is the art of making what you want from what you can get at a profit.
You know I worry about people polluting the clean vacuum of space. How will we be able to restore it to the conditions that existed before the dirty pollution was injected into the clean vacuum?
If you're irrational about the living environment, your a greeny. If you irrationally care about the sold dead environment of space, what does that make you? A voidy? Maybe a blacky? Hm.
On the other hand MSimon, while I think you were injecting some levity, it is a good point that debris in popular orbits can be dangerous. Different relative velocities where different orbits intersect and all that. I assume that by the time we're producing enough debris to be dangerous, we'll have enough infrastructure in place to deal with it.
I remember seeing an article about cleaning orbit with lasers. Everybody likes space lasers.
TallDave wrote: How do you get the ore to the ground? I don't think you can refine it out there.
A great trilogy (the "Rosinante" series by Gilliland) points out that once one is out in solar orbit (astreoids, remember), the possiblity of zone refining of mixed metals becomes fairly easy (constant, highly focusable, sunlight). Zone refine the megatonnes of iron to winnow out the ~1% of valuable metals at the high and low melting point ends, and ship the high value metals.
Excellent story too!
I should look up those books. I like a good hard sci fi.
I was assuming something like that would be possible with the large amounts of energy available in space, but this isn't my industry at all, so I kept my mouth shut.
A major bonus is all the leftover iron in space. You could ship it to a stable orbit and provide materials for orbital colonies.
