(re: Ice King crown) – It is an interesting proposition – but I think you might have forgotten that enthalpy works both ways. It takes specific and finite energy to dissociate oxygen to a vapor phase, and it releases a specific and rather significant amount of energy on being condensed to liquid/or/solid. If less-than-88K is needed, remember that all the condensate will be pushing temperatures UP, with only black-body radiation available to cool everything down.

*Now, while there are a LOT of seconds in a year (31.5 million of them), 11 tons per square meter per year is still 0.35 grams per sq. meter per second. *

31536000 |
s (yr) |

11000000 |
g (oxy) |

0.35 |
g/s |

6.8 |
kJ/mol |

32 |
g/mol |

0.01 |
mol/s |

74.12 |
J/s |

So… 75 additional watts of heat per square meter. Feel like doing the Black-Body thing and calculating both backward what “88K” (converted to blackbody watts) + 75 watts … reconverted back to degrees K is? I don’t think it is close to 88K.

So… 75 additional watts of heat per square meter. Feel like doing the Black-Body thing and calculating both backward what “88K” (converted to blackbody watts) + 75 watts … reconverted back to degrees K is? I don’t think it is close to 88K.

[calculating]

OK, 88 K equals 3.4 watts per square meter.

190.15K equals 74.12 watts per square meter.

Obviously… too high a temperature to equalize into a workable Friedlander steady-state oxygen trap.

Indeed … your budget is actually more like “1 watt per square meter” above and beyond the natural background lunar regolith output. So… instead of 11 tons/square meter per year, adjust down by 1/75th of that. Maybe then it’d work.

*=GoatGuy=*

Chemical composition of the lunar surface regolith (derived from crustal rocks)

Compound Formula Composition (wt %)

Maria Highlands

silica SiO2 45.4% 45.5%

alumina Al2O3 14.9% 24.0%

lime CaO 11.8% 15.9%

iron(II) oxide FeO 14.1% 5.9%

magnesia MgO 9.2% 7.5%

titanium dioxide TiO2 3.9% 0.6%

sodium oxide Na2O 0.6% 0.6%

Total 99.9% 100.0%

Note that this is one set of tables on a global average, specific sites could for example double the titanium (and note also these are expressed as oxides, so for example that’s not 4% titanium but more like 2%.in the table above.–But in the Sea of Tranquility, for example, you could probably get 4% in random regolith. If you can export from multiple sites, you can often find 10% iron, in a separate place 4% titanium, perhaps 12%+ aluminum, and at another site as much magnesium–using totally different regolith types.)

Keep in mind that by weight oxygen is about 40 % of the lunar regolith and silicon and calcium together around 30 % and you will see that potential export metals are only about a quarter of regolith weight.

http://nextbigfuture.com/2010/03/in-praise-of-large-payloads-for-space.html

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