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I read in a lot of places that for some reason the moon lacks carbonates, and thus carbon. Part of the reason seems to be the lack of biological origin and cycles. But are there no other sources for getting carbon on the moon if the need arises?

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  • $\begingroup$ Some information is here 1, 2, 3. Deposits of biological origin like coal and oil like on earth could not exist on the Moon. But may be there are unfound deposits of graphite below surface? $\endgroup$ – Uwe Jan 7 '18 at 13:51
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    $\begingroup$ "lacks carbonates, and thus carbon" - those things are not exactly connected. Good article, on a bit different subject airspacemag.com/daily-planet/how-much-water-moon-180967751 , but pay attencion to The LCROSS impact part of it. "C" gets oxidized or reduced so CO, CHx there - so basically surface carbon evaporates because of reduction environment of the moon(solar wind, hydrogen and that) So thus over geological time it kinda tends to evaporate from the surface. At poles same as water traps, you should expect to find carbon, for the same reason as water. rest to be discovered. $\endgroup$ – MolbOrg Jan 7 '18 at 14:24
  • $\begingroup$ Graphite was found in samples from Apollo 17 some years ago, see. $\endgroup$ – Uwe Jan 7 '18 at 17:50
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There is a lot of carbon in the solar system without biological origin. Carbonaceous chondrites make up about 5% of meteorite falls. Astronomers have matched the spectral signature of asteroids to c chondrites. There are several categories but they look like coal. These contain plant nutrients and plants have been grown in them. https://www.newscientist.com/article/mg22430004-900-asteroid-soil-could-fertilise-farms-in-space/ So if this kind of thing exists on the moon, it would be great for colonists.

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    $\begingroup$ Of course all carbon in the solar system had no biological origin at first. But if a carbonaceous chondrite hits the moon, it heats up very much and carbon bound to other elements may outgas as carbon dioxide, see. But the moon has no atmosphere in which the carbon dioxide could be a part of. $\endgroup$ – Uwe Jan 8 '18 at 10:38
  • $\begingroup$ I believe the crust of the moon is inactive. That would mean that it doesn't circulate material from below to the surface. The bleaching effect on the surface would not effect anything below a certain depth. How deep could that reduction environment penetrate? Not far I would think. By that logic there could be substantial carbon deposits under the surface left over from the creation of the moon. $\endgroup$ – Johnny Robinson Jan 9 '18 at 2:03
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If you accept the theory that the Moon was created out of a collision with the early Earth, then the significant heating during that event would have baked most of the volatiles (water, carbon) out of the coalescing Moon. IIRC carbonate minerals are a result of leaching rocks with water with dissolved CO2 (carbonic acid), both of which would likely be absent per theory.

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Carbonate rock like limestone is formed primarily from skeletal remains of marine animals like corals and molluscs and involves sedimentation under water. Other carbonate minerals can be formed by metamorphic processes (marble) and evaporative crystalisation of dissolved carbonate minerals (tufa/travertine) - from carbonate derived from pre-existing carbonate rocks. It is not expected to be present on The Moon because of the absence of carbonate forming organisms and water/atmosphere.

Materials containing carbon with non-life origins should exist on the moon such as primordal or infalling carbonaceous chondrite material.

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