Mars polar cap:a habitat for elementary life

摘要

Ices in the Martian polar caps are potential habitats for various species of microorganisms.Salts in the ice and biological anti-freeze polymers maintain liquid in cracks in the ices far below 0possibly down to the mean 220-240 K. Sub-surface microbial life is shielded from ultraviolet (UV)radiation, but could potentially be activated on south-facing slopes under the midday, midsummer Sun.Such life would be limited by low levels of vapour, little transport of nutrients, low light levels below aprotective dirt-crust, frost accumulation at night and in shadows, and little if any active translocation oforganisms. As in the Antarctic and in permafrost, movement to new habitats depends on geo-climaticchanges, which for Mars's north polar cap occur on a 50 000 year scale, except for rare meteoriteimpacts.