Surprising Fact, Internal Lunar Temperature

From Infoplease, Moon : Physical Characteristics

Internal Structure

Diffraction of seismic waves provided the first clear-cut evidence for a lunar crust, mantle, and core analogous to those of the earth. The lunar crust is about 45 mi (70 km) thick, making the moon a rigid solid to a greater depth than the earth. The inner core has a radius of about 600 mi (1,000 km), about 2/3 of the radius of the moon itself. The internal temperature decreases from 830°C (1,530°F) at the center to 170°C (340°F) near the surface. The heat traveling outward near the lunar surface is about half that of the earth but still twice that predicted by current theory. This heat flow is directly related to the rate of internal energy production, so that the internal temperature profile provides information about long-lived radio isotopes and the moon's thermal evolution. The heat-flow measurements indicate that the moon's radioactive content is higher than that of the earth....

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David - No, the ores there

David -
No, the ores there showed a lower ratio of U235 to U238 than elsewhere, indicating that more fission than normal had occurred in the ore. The geological conditions (water acting as a moderator is main theory) encouraged more fission in that deposit than in other deposits that all started out with the same, un-enriched ratios of isotopes.

Lab Rat, weren't the natural

Lab Rat, weren't the natural reactors at Oklo "breeders"? If so then the uranium there is (or was) naturally enriched.

Jonathan- A few points:

Jonathan-
A few points: radioactive isotopes are not necessarily (and most likely not) easily fissionable to make energy, and "enriched" isotopes do not exist in nature - the are enriched by man, at great effort.

Interesting. I knew about

Interesting. I knew about the internal temperature bit. Right near the surface (as in a few feet down), the temperatures get down to a rather reasonable range. A lot of the ideas I've seen proposed for building stuff on the moon takes advantage of this much more stable thermal environment by having the buildings buried or dug into the lunar surface.

The bit about the Moon having more radioactives is potentially interesting. Having radioactives available on the moon vastly simplifies the whole nuclear question. If you don't have to ship it up from the earth, most of the political problems go away. Now we just need to figure out how, if the moon really does have more radioactives in its core, any of that could have reached the surface in the past. I wonder if there are any really deep craters that might have enriched radioactives.....maybe this is where that KREEP stuff came from.....

Anyhow, that's probably a little to space nerdy for this site. I now return you to your regularly scheduled political philosophizing.

Lab Rat, While it is true

Lab Rat,
While it is true that many of the naturally radioactive isotopes aren't readily fissionable, the heavy metal isotopes like U238 and Th232 (or was it Th233?) that are the most likely what is there can be converted to fissionables in a breeder type reactor. Sure that's an artificial process, but if such materials are available in economically minable quantities on the moon anywhere, there are many ways to generate the neutrons needed for the process. In fact, with some reactor schemes I've seen, even unenriched or depleted uranium can be made fissionable with a powerful enough neutron source with neutrons at the right energy level.

~Jon

Maybe it's time to stripmine

Maybe it's time to stripmine the moon.