[dandelany]

> So if you find x living microbes at 200km from Earth, given thermal dispersion, shouldn't there be some y number of molecules from Earth on the Moon?

I doubt it - even if the "uplifting air currents" hypothesis were proven true, there's a massive difference between low earth orbit and the moon. Around 8 km/s of delta-V to be exact.[1] This means that, to make it to the moon, the molecule not only has to reach LEO, it has to be moving at 8 km/s (a pretty insane speed) by the time it gets there. I can't imagine any earthly air current moving that fast, in fact it's likely impossible because the speed of sound is only 0.35 km/s.

[1] https://en.wikipedia.org/wiki/Delta-v_budget#Earth-Moon_spac...