The Moon is, for obvious reasons, rarely considered an interesting venue for astrobiology. But I’ve been looking through Joop Houtkooper’s presentation at the European Planetary Science Congress, noting his contention that some lunar craters might hold samples of life from the early Earth, and perhaps even from Mars. If the name Houtkooper rings a bell, it may stem from the splash he made last year by suggesting that the Viking probes to Mars may have discovered Martian microbes consisting of fifty percent water and fifty percent hydrogen peroxide.
Although some extremophiles here on Earth put hydrogen peroxide to use, the theory is quite a long shot. But then, Houtkooper (University of Giessen, Germany) seems to thrive on remote possibilities. His lunar theory works like this: Certain craters on the Moon are effectively shielded from sunlight, at least deep within their recesses. Shackleton crater at the south pole is a case in point, a place that may contain sub-craters free of even reflected light from the crater edges. These ultra-cold places might preserve any life that found its way there.
Ancient meteorites would be the source of that life, debris blasted off a primordial Earth by various impacts. It is even conceivable, though at the outer edges of possibility, that we might find viable microbes that have survived the intervening eons in a dormant state. Let me quote from an abstract of Houtkooper’s talk that is available online:
Some of this biogenic material would have likely been preserved on the Moon, probably frozen into the regolith and later being covered by lunar dust. Some of its microbial load, dislodged with rocks from Earth, might have survived the transport to the Moon, and would have possibly remained in a viable state if buried quickly under the radiation reworked surface. Some of these organisms may have even landed in lunar locations, where liquid water was present for a temporary period. These pockets of water would have been small in extent, possibly microscopic, within an excavated impact crater. Perhaps, these impact zones would have provided suitable conditions to support a highly localized biosphere for a limited period of time. Given the dryness of the Moon, its lack of a substantial atmosphere and lack of dynamic activity, we consider it unlikely that any surviving microbes would still be active on the Moon, but it is not entirely impossible if liquid would be found beneath the lunar ice in some locations. More likely, however, is that these temporarily existing liquid water pools froze and may still hold viable microbial organisms, possible even organisms that extended their life time for a short while on the Moon.
Houtkooper is suggesting that a large enough impact could create a temporary and vanishingly thin lunar atmosphere that conceivably could call dormant life back into action. Life on the Moon. The odds seem astronomical, but the chance to study ancient microbes from our planet’s earliest history, and perhaps microbes from Mars as well, would make this an investigation worth pursuing if we were in the vicinity anyway. The search for lunar ice at the bottom of such craters could make this a possibility for future manned missions. See also this piece in Astrobiology Magazine on earlier work by John Armstrong, Ian Crawford and Emily Baldwin on the survival of biological markers from Earth on the Moon.