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Author Topic: Helium 3  (Read 9133 times)

sooyeah

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Helium 3
« on: 10/12/2007 10:55:34 »
Had an idea,
 
Some people were thinking about going to the moon to mine for helium 3. This is produce by the solar wind.

My idea is could we, rather than going to the moon to mine, place a satellite designed to catch helium 3, in orbit, to catch the solar winds particles and then harvest it? You could fill the satellite with pods which would be used to return the compound, once a pod became full it could then be released and remotely flown back.

All you would need to do it go up to the satellite once all the pods had been used and refill it.

I think it would work out alot cheaper than mining the moon and probably be alot safer.


 

sooyeah

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Helium 3
« Reply #1 on: 10/12/2007 11:11:53 »
There could be safety issues with the returning pods. How dangerous is helium 3?
 

another_someone

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Helium 3
« Reply #2 on: 10/12/2007 13:18:04 »
3He is perfectly safe, so that is not the issue.

The problem is that while it is true that the moon has more 3He than on Earth (it actually does not have very much at all, it is simply that we have even less), and it is true that the 3He came from the solar wind, it took billions of years to collect what there is there (the solar wind has very little of anything, which is why it is typically regarded as a near vacuum, but it has just enough that if you stand there for billions of years you might collect a usable amount of something).

So, yes, if you put a large satellite up there for millions, or billions of years, you might get something useful; but simply putting up a satellite up there for 5 years will not come back with anything more than you could just about measure with very specialist equipment - certainly not even a minute  fraction of anything that would be a useful amount.
 

sooyeah

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Helium 3
« Reply #3 on: 11/12/2007 13:12:28 »
3He is perfectly safe, so that is not the issue.

The problem is that while it is true that the moon has more 3He than on Earth (it actually does not have very much at all, it is simply that we have even less), and it is true that the 3He came from the solar wind, it took billions of years to collect what there is there (the solar wind has very little of anything, which is why it is typically regarded as a near vacuum, but it has just enough that if you stand there for billions of years you might collect a usable amount of something).

So, yes, if you put a large satellite up there for millions, or billions of years, you might get something useful; but simply putting up a satellite up there for 5 years will not come back with anything more than you could just about measure with very specialist equipment - certainly not even a minute  fraction of anything that would be a useful amount.

Is that a definite? If the satelite was designed to collect it, maybe we could gather more than we expect.
Do we really understand the particles inside the solar wind that well? If nothing else the satellite, I suggest could help us understand it better.

Do we even know the reason why helium 3 has attached to the moon in the first place?

My point being are you not arguing from the point of assumption?
 

Offline Bored chemist

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Helium 3
« Reply #4 on: 11/12/2007 19:45:38 »
We can judge the composition of the solar wind quite well because we have sent instruments into space to measure it.
There simply isn't that much 3He no matter how you collect it.
 

another_someone

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Helium 3
« Reply #5 on: 11/12/2007 21:01:48 »
Is that a definite? If the satelite was designed to collect it, maybe we could gather more than we expect.

Ofcourse, we can always speculate about the possibility of some, as yet, unknown factor; but what might reasonably be judged is that there is not that much of anything in the solar wind (even if it was 100% 3He, it would still not be a lot).  If there was any substantial amount of matter within the solar wind, it would cause significant amounts of drag on any Earth satellite (including the Moon itself), and they would have all fallen down to Earth long ago.  The fact that they still remain in orbit clearly indicates that there is not a lot of matter of any kind up there to cause any substantial drag.
 
Do we really understand the particles inside the solar wind that well? If nothing else the satellite, I suggest could help us understand it better.

Bored Chemist has already answered that, so no point in repeating what he has said.

Do we even know the reason why helium 3 has attached to the moon in the first place?

3He is probably not any more attracted to the Moon than the Earth, but the difference is that the Earth has an atmosphere that surrounds it, so 3He never gets to ground level, whereas the Moon has no atmosphere, so 3He actually hits the rocks at the surface, and gets embedded into the.  There may also be some effects due to the Earth's magnetic field, which to some extent does protect us from some aspects of the solar wind, but I do not know if this applies to 3He (on the other hand, most artificial satellites are also protected by that same magnetic field).
« Last Edit: 14/12/2007 05:49:10 by another_someone »
 

Offline Bass

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Helium 3
« Reply #6 on: 12/12/2007 05:33:11 »
Hot spots, such as Hawaii, Iceland and Yellowstone, have measurably higher than normal 3He.  So do some oilfields.  Hot spots are thought to have more "primordial" material, which could account for the 3He.  Not sure about oil fields, maybe JimBob would know?
« Last Edit: 12/12/2007 05:35:03 by Bass »
 

Offline daveshorts

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Helium 3
« Reply #7 on: 12/12/2007 10:32:14 »
Yes the problem with mining the solar wind directly is that there are only about 1-10 million particles per cubic metre they are moving at about 300 000m/s so you would get 0.3 - 3 trillion particles passing per second per square meter but only about 1 in 10000 of these will be helium 3

So you are looking at about a billion helium 3 atoms per square metre per second which sounds a lot, but there are about 200 000 000 000 000 000 000 000 atoms of helium 3 in a gram.

So even if you could collect all the helium 3 in a square km of space you would have to wait 200 000 000 seconds or about 6 and a half years to get a gram of the stuff.

 

sooyeah

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Helium 3
« Reply #8 on: 12/12/2007 13:35:39 »
Yes the problem with mining the solar wind directly is that there are only about 1-10 million particles per cubic metre they are moving at about 300 000m/s so you would get 0.3 - 3 trillion particles passing per second per square meter but only about 1 in 10000 of these will be helium 3

So you are looking at about a billion helium 3 atoms per square metre per second which sounds a lot, but there are about 200 000 000 000 000 000 000 000 atoms of helium 3 in a gram.

So even if you could collect all the helium 3 in a square km of space you would have to wait 200 000 000 seconds or about 6 and a half years to get a gram of the stuff.

Well that is of course relative to the size of the satellites catch area and the time of the harvesting.
What your saying is that we could do it but it will take a long time to gather good amounts, surely the amounts of 3HE vary in the solar wind, with sun spots etc.
The placement of the satellite, it's size, the amount of time afforded to collect 3HE, sun spots, will all effect the satellite ability to gather it.

As an extended idea could you not funnel a bigger area to the satellite? So instead of making a huge satellite you could funnel the solar wind itself.

So you would have a small satellite, that would achieve the benefits of a huge one. It would have to be funnelled away from the earth just in-case it broke, obviously. So I'm suggesting condensing the solar wind with some kind of funnel into a satellite trap.

The funnel wouldn't need to be heavy, it would just divert the wind towards the satellite. That way you could cover a far bigger area and keep a small satellite collection point.     
 

Offline daveshorts

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Helium 3
« Reply #9 on: 12/12/2007 13:54:08 »
It would however be very difficult to catch something moving at 300 km/s even if it is as small as a helium nucleus. So whilst you could in principle concentrate the solar wind using a huge superconducting magnet I think it would have to be infeasibly strong to have much effect on the particles.

The other problem is that the energy flux in terms of helium 3 is tiny. If you could convert all the nuclear energy in the helium 3 as it passes through your machine you are sill going to be collecting only about 80 μW /m2 which when compared to the solar energy coming through which is about 1kW/m2 is tiny.

So it definitely wouldn't be economic to collect it in earth orbit, as energy collection with solar panels certainly isn't economic atm and that is giving you 100000 times more energy per square metre.
« Last Edit: 12/12/2007 17:12:25 by daveshorts »
 

Offline Bored chemist

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Helium 3
« Reply #10 on: 12/12/2007 18:39:00 »
Since the huge funnel would also need to be in orbit, it would be a huge satelite.
So, rather than have a huge satelite gathering 3He, you have a huge satelite and feeding a second satelite.
I don't see how that's better.
 

Offline wolfekeeper

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Helium 3
« Reply #11 on: 14/12/2007 03:46:46 »
He3 is completely useless at the moment anyway; burning He3 requires a working fusion reactor, and fifty years ago it was fifty years away. Now it's only 30 years away! Now that's what I call progress!
 

sooyeah

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Helium 3
« Reply #12 on: 29/12/2007 16:51:42 »
Since the huge funnel would also need to be in orbit, it would be a huge satelite.
So, rather than have a huge satelite gathering 3He, you have a huge satelite and feeding a second satelite.
I don't see how that's better.

I was actually thinking of using as minimal an area (with regards to the turning of the solar wind) as possible, the point being that you get as much benefit of a giant satellite, but you would only be using a small one, the two wouldn't necessarily be connected and could have a big space between them.

The first would just be a barrier which redirects the solar wind towards the satellite, the ways in which you could achieve that are vast.

To be honest it's probably too dangerous to play about with that anyway, just an idea.
 

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Helium 3
« Reply #12 on: 29/12/2007 16:51:42 »

 

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