Relevant to this question. NASA says the very thin vacuum like Lunar atmosphere has sodium and potassium Does creating a very thin vacuum like lunar atmosphere of the metal atoms leftover after mining for water and helium-3 make sense?

As the lunar atmosphere would be very thin, very light atoms such as proton and alpha particle would penetrate but high energy ions from cosmic ray would be shielded because they would bounce off those silicon atoms?

Escape velocities of gases at various temperatures on top of planets and celestial bodies,

New question: How about a Krypton or Xenon atmosphere?

physical properties of krypton, physical properties of xenon

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    $\begingroup$ Short answer: NO. Long answer: good grief No.. detail: 1) way too thin(about 40 trillion times too thin).. 2) cosmic rays don't work like that, you want light atoms like hydrogen to slow them down. big atoms just shatter. 3) what silicon, when you link about Sodium and Potassium? $\endgroup$
    – PcMan
    May 2, 2021 at 23:13
  • $\begingroup$ I think that you'll find that the escape velocity of the moon at the atmospheric temperature needed for gaseous Sodium/Potassium would not permit an atmosphere, see (the ever popular): Atmospheric escape-velocity graph as a reference. $\endgroup$ May 2, 2021 at 23:37
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    $\begingroup$ @PcMan how about posting that as an answer rather than a comment $\endgroup$ May 3, 2021 at 2:04
  • $\begingroup$ @KerrAvon2055 because if i did that, then someone would trot out that planetary-atmosphere chart, and say im an idiot because neither sodium not silicon is on the chart. Then some other person will say im an idiot, because the moon has no mangetosphere, and will be instantly stripped of all atmosphere by solar wind. Then another person will cal that one and idiot. End result: much bad vibes all round, multiple people banned, and.... no thank you. Oh wait, the first part has already happened. Eeek! $\endgroup$
    – PcMan
    May 3, 2021 at 8:12
  • $\begingroup$ What? I never called anyone an idiot! (out loud) @PcMan $\endgroup$ May 3, 2021 at 8:34

2 Answers 2


I think we can say that no, it doesn't make much sense from a human perspective.

Sodium and potassium are both extremely reactive when in their pure form, already as solid. Even worse, they react very energetically with water, releasing a lot of heat, to the point that a chip of sodium or potassium put in water float above a thin layer of water vapor and produces a lot sparkles.

Having an atmosphere of those two nasty atoms would make the requirements for the spacesuits even more severe, because they'd need to be resistant also to those aggressive atoms, which even worse would need to be at fairly high temperature to not condensate into a solid.

That said, an atmosphere makes sense if all the chain reactions happening from impact with cosmic rays and particles happen far away from the inhabited surface, so that most of the energy is dissipated where it doesn't hurt, which means that a too thin atmosphere could be even worse than no atmosphere, because it would act as a multiplier or the particles due to the above said impacts.

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    $\begingroup$ Yup, in all cases a poor radiation shield fares worse against cosmic rays than no shield at all. Do it right or don't do it at all. $\endgroup$ May 3, 2021 at 5:34

A sodium/potassium atmosphere would be terrible for supporting any form of life due to the reactions with water that L. Dutch mentioned. Your atmosphere would have to be devoid of water or risk producing a chain reaction.

Your post mentioned "mining for water" - better hope the uncovered water doesn't come into contact with sodium and potassium particles, because the water could quickly turn into uncovered disappointment coupled with a blast that knocks the miners off their feet.

Perhaps the biggest impracticality that L. Dutch's post doesn't already address is charged particles. The earth has a magnetic field that traps charged particles from the sun in "Van Allen" belts. Without a magnetic field, harmful charged particles ("solar wind") could hit the surface in large volumes. Solar wind would blast away whatever atmosphere remains (https://www.nasa.gov/press-release/nasas-maven-reveals-most-of-mars-atmosphere-was-lost-to-space). Read https://futurism.com/recent-news-on-earths-van-allen-radiation-belts for an explanation of why life on a planet without a magnetic field can be miserable.

The moon doesn't have a significant magnetic field compared to earth (see https://en.wikipedia.org/wiki/Magnetic_field_of_the_Moon). If you want to keep a maintainable atmosphere, you will need to install one.

  • $\begingroup$ I don't think the OP was implying an atmosphere for habitability. Looks like they wanted an atmosphere functionally opaque to cosmic rays. $\endgroup$
    – BMF
    May 3, 2021 at 23:43
  • $\begingroup$ Well, an atmosphere functionally to shield the Moon from cosmic rays and as @user1258361 expressed, a functional magnetosphere. May I know your definition of opaqueness concerning this case of the Moon? Cosmic rays and solar winds are comprised mostly of gamma rays and high energy protons. $\endgroup$
    – Kav
    Oct 6, 2021 at 17:26
  • $\begingroup$ Can the artificial atmosphere functionally incorporate them into the atmosphere as they bombard it and it also shields the Moon? The Moon lacks atoms of light chemical element, hydrogen and helium atoms from solar winds would contribute themselves just that, not mention their high energies could contribute to the warming of the Moon. $\endgroup$
    – Kav
    Oct 6, 2021 at 17:27
  • $\begingroup$ As for the magnetosphere, how about dumping all the heavy chemical element such as thorium and the nuclear wastes from Earth into the core of the Moon? Not any mined helium-3 though. Then could the energy from radioactive decay reheat the core? In FANTASY, maybe a wormhole could be opened as the tunnel to send the wastes and the thorium, one batch at a time and then closed. As it is fantasy, let us not concern with it. $\endgroup$
    – Kav
    Oct 6, 2021 at 17:32

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