Helium 3

[Oakleaf51]

What is so special about this isotpe of helium that newspapers reported, Nasa could be thinking of mining from below the Moons surface? Don't we have any here on Earth, and if not, why not?

[fo3nix]

It's all about nuclear fusion.

http://en.wikipedia.org/wiki/Helium-3
(see opening paragraph)

Fusion is the hot thing (pun not intended), that's been talked about lots for decades. It's far better than fission (what nuclear power stations do now), but the materials commonly used to achieve fusion causes damage to the machine inside, meaning it has to be replaced every so often (and far too often for proper industrial use). It's been found that 3He is a good substitute that allows the walls of the machine to last longer, and hence why it's wanted (fusion is one of these cure-all energy problems solutions).

3He isn't a natural isotope, and is very (very) expensive to produce. Quite a bit of research goes into using it at ultra low temperatures, but apart from that I'm not really sure. It can be produced for this purpose, so in theory I guess that it could be used for fusion too (though I know nothing about this), but perhaps the moon solution is cheaper (hard to imagine, but I think 1ltr of 3He costs in the region of �10,000)?

[newtron]

Actually, as stated in the link you provided fo3nix, 3He is a naturally occuring isotope which is produced in the atomosphere and the earth by lithium spallation, cosmic rays, and decay of tritium (3H). It is rare though.

[jake-the-peg]

The Nuclear Fuson that we are working on involve using Duterium and Tritium ( heavy forms of Hydrogen)

These reactions resuly in highly energetic neutrons which cannot easily be controlled hit the reactor wall and degrade it over time so the Torus walls need to be regularly replaced which is difficult.

The reaction of Duterium with Helium 3 results in protons, because they are charged they can be diverted by magnetic fields extending the life of the reactor.

BUT - there are drawbacks:

1/. Some of the Duterium will react with itself meaning you cannot elliminate high energy neutrons completely

2/ This reaction requires a much higher temperature and is much harder to achieve ignition.

3/ The Helium 3 reaction results in much higher x-ray losses which are as much a hazard as the neutrons.

All in all even if you turned up with a lorry load of Helium 3 at Cadareche, the JET->ITER -> DEMO bandwagon is so on track I doubt anybody would be very interested at looking at a fresh technology that may well turn out to have worse problems than deuterium-tritium.

I think the Lunar Helium 3 issue may have more to do with justifying manned space flight than fulfilling a real urgent need

[jake-the-peg]

Oh If you're interested in Fusion - see here:

http://www.iter.org/

[fo3nix]

Ahh ok you got me there. I'm definitely no expert. But I think my point about it still being rare is valid as you say.

[Muppit]

Wrong wrong wrong wrong wrong..... you are all thinking like scientists, try thinking outside of the box......

NASA have just realised that they are pretty close to destroying the Earth. (By bringing moon rocks back to Earth, they are increasing it's mass and therefore it's gravitational field strength. At the same time, they are making the moon lighter, thus reducing it's gfs.)

In order to maintain a steady gfs ratio, and stop the moon ploughing into the Earth at an 'astronomical' rate... they must increase the relative mass of the moon, (by removing buoyancy in the form of helium) and lower the effective mass of the Earth by adding helium!

Yes, I am only kidding, but I am worried about all of those moon rocks coming back here. Though a reduced distance between the Moon and the Earth would have some benefits, such as more exciting longer lasting soalr eclipses.