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The moon has helium? It sounds like it comes from alpha-decay of radioactive elements and I don't think the moon has much of that given its size, no iron core a

by lutorm 17y ago

The moon has helium? It sounds like it comes from alpha-decay of radioactive elements and I don't think the moon has much of that given its size, no iron core and all. But I'm not a planetary scientist...

tjic 17y ago
Helium can be created by ions striking hydrogen. Helium is also created by hydrogen fusing in the sun and being blown out on the solar wind.
- lutorm 17y ago
  Actually, the helium in the solar wind is not the helium the Sun has made, it's primordial. The helium made by the Sun is in the core and does not get to the surface, because the Sun's convective layer does not reach into the part where fusion is happening.
xiaoma 17y ago
Not only does the moon have a great deal of helium, It's got vast stores of the He3 isotope. http://www.telegraph.co.uk/news/worldnews/1550246/Russia-sees-moon-plot-in-Nasa-plans.html http://www.telegraph.co.uk/news/worldnews/1550246/Russia-see...
Daniel_Newby 17y ago
The moon has large amounts of He-3 compared to Earth, acquired as atoms of it were jammed into the rocks by the solar wind.
- lutorm 17y ago
  Good point. I can't believe there's that much mass arriving in the solar wind, though.
  - afterburner 17y ago
    Give it several billion years and it adds up.
streety 17y ago
I recall that one of the reasons frequently given for returning to the moon is that it is "rich" in Helium-3 (the commonest isotope is Helium-4) and it can be used in nuclear fusion[1]. If wikipedia is to be believed "rich" is relative here and corresponds to 0.01 ppm. He-4 is slightly better at 28 ppm. However as He-4 is 5ppm [2] of the atmosphere here on Earth the Moon seems a long way to go to achieve just a 6-fold enrichment. [1] http://en.wikipedia.org/wiki/Helium-3 http://en.wikipedia.org/wiki/Helium-3 [2] http://en.wikipedia.org/wiki/Atmosphere_of_Earth#Composition http://en.wikipedia.org/wiki/Atmosphere_of_Earth#Composition
- IgorPartola 17y ago
  Helium-3 is also extremely useful when it comes to cryogenics. Since it is 25% lighter than Helium-4, it is easier to boil it off to reach temperatures below 1 degree K. In the systems that use Helium-3 it's usually a closed circuit system and loss of helium is considered to be a big deal since it's expensive.

by lutorm 17y ago

tjic 17y ago

Helium can be created by ions striking hydrogen. Helium is also created by hydrogen fusing in the sun and being blown out on the solar wind.

lutorm 17y ago
Actually, the helium in the solar wind is not the helium the Sun has made, it's primordial. The helium made by the Sun is in the core and does not get to the surface, because the Sun's convective layer does not reach into the part where fusion is happening.

xiaoma 17y ago

Not only does the moon have a great deal of helium, It's got vast stores of the He3 isotope. http://www.telegraph.co.uk/news/worldnews/1550246/Russia-sees-moon-plot-in-Nasa-plans.html http://www.telegraph.co.uk/news/worldnews/1550246/Russia-see...

Daniel_Newby 17y ago

The moon has large amounts of He-3 compared to Earth, acquired as atoms of it were jammed into the rocks by the solar wind.

lutorm 17y ago
Good point. I can't believe there's that much mass arriving in the solar wind, though.
- afterburner 17y ago
  Give it several billion years and it adds up.

streety 17y ago

I recall that one of the reasons frequently given for returning to the moon is that it is "rich" in Helium-3 (the commonest isotope is Helium-4) and it can be used in nuclear fusion[1]. If wikipedia is to be believed "rich" is relative here and corresponds to 0.01 ppm. He-4 is slightly better at 28 ppm. However as He-4 is 5ppm [2] of the atmosphere here on Earth the Moon seems a long way to go to achieve just a 6-fold enrichment. [1] http://en.wikipedia.org/wiki/Helium-3 http://en.wikipedia.org/wiki/Helium-3 [2] http://en.wikipedia.org/wiki/Atmosphere_of_Earth#Composition http://en.wikipedia.org/wiki/Atmosphere_of_Earth#Composition

IgorPartola 17y ago
Helium-3 is also extremely useful when it comes to cryogenics. Since it is 25% lighter than Helium-4, it is easier to boil it off to reach temperatures below 1 degree K. In the systems that use Helium-3 it's usually a closed circuit system and loss of helium is considered to be a big deal since it's expensive.