Date:8 June 2013 Tags:,

Signs of life? – Steve Rousseau

After analysing the first drilled-rock sample on Mars, Nasa scientists announced in March that the planet once could have supported life, calling it the first definitive evidence of a habitable extraterrestrial environment. Researchers found the key ingredients to foster microbial life, such as sulphur, nitrogen, hydrogen, oxygen, phosphorus and carbon, in the material drilled out of an ancient stream bed called Yellowknife Bay.

More importantly, the probe also found water with a neutral pH. “We have found a habitable environment that is so benign and supportive of life that probably, if this water was around and you had been on the planet, you would have been able to drink (it),” said John Grotzinger, Mars Science Laboratory project scientist. Next, the team will look for stronger signs of organic carbon in the same areas, where, roughly 3 billion years ago, Mars might have had living creatures.

Three heralds of habitability:

  1. Clay minerals in the subsurface tailings suggest that the sedimentary rock of Yellowknife Bay formed in water with a neutral pH level. Grotzinger said: “We don’t see iron sulphate, which indicates acid pH; instead, we see calcium sulphate.”
  2. The clay in the sample came from igneous materials mixed with freshwater. The clay, combined with sulphate, suggests the water that once flowed in Yellowknife Bay was neutral or slightly alkaline and therefore pure enough to sustain life.
  3. The Gale Crater contains minerals, such as magnetite, that could have been food for microbes. The surface soil has been turned red by oxidation, but the grey sample soil indicates that it’s been less damaged by oxygen and is therefore more likely to preserve the Martian past. Differing oxidation levels indicate the flow of electrons, from which microbes could have drawn energy.

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