With current knowledge of extraterrestrial environments in the planets of the solar system it's obvious that many appears to susceptible to sustain life similar to the extreme environments on earth. As far as we know with present data Martian surface is not supportive for life. However regions such as Meridiani Planum and southern highlands represent environmental conditions similar to Atacama Desert, the Antarctic Dry Valleys, the Rio Tinto region, and the deep basalt aquifers. Widespread chloride deposits, endolithic habitats on the basaltic rocks may harbor life powered by chemoautotroph similar to the eco systems found on earth. One of the very intriguing discovery about the Martian atmosphere is the trace amounts of methane which is highly unstable. Roughly its estimated annual production of methane is 270 tons and this phenomenon is highly unlikely due on volcanism or hydro-thermal activity. The exact source is still remaining as a mystery and it could a bi product of a life form such as methanogene.
Europa, one of the four major moons of Jupiter presents an internal structure consists primarily with silicate rock and iron core with presence of subsurface ocean about 100 km thick covered with ice crust. The dynamic activity of the on the surface clearly indicate the tidal forces deep sea vents beneath and possible life on sub glacial ocean. Lake Vostok in Antarctica is the largest and deepest known subglacial lake and 3623m drilling were required to penetrate the ice cover for paleoclimate studies. This lake represent possible analog to Europa's environment and the life of the Vostok Lake sustain life with symbiotic relationships which involve lithoautotrophic microorganisms that use chemical energy to support metazoans without photosynthesis. In addition the outer ice crust which is estimated to 20-30km thick protects the inner ocean from the Jovian and solar radiation exposure.
Previous paradigms about the evolution and existence of life have changed with the studies on extreme environmental conditions. Still large number of species and on deep subocean and subterranean regions remain unknown to science. The inspiration suggest that many places of the solar system supports life which previously thought to be inhabitable such as Venus, Enceladus, Io, Titan, and cerus. The exploration just initiated and more fascinating discoveries on near future would change the contemporary dimension on nature of life.
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