The Curiosity rover landed on the red planet in summer 2012 in the Gale crater. NASA announces that it has discovered the presence of organic molecules on Mars and has revealed seasonal variations in methane.
" Without necessarily being evidence of life itself, these results are a good sign for future missions to explore the surface and underground of the planet ", writes the US Space Agency.
Organic matter was identified in samples of sedimentary rock 3.5 billion years old and collected only 5 cm deep. " Organic molecules contain carbon and hydrogen, and can also contain oxygen, nitrogen and other elements. "
However, NASA specifies that if such organic molecules " are generally associated with life, they can also be created by non-biological processes and are not necessarily indicators of life. "
Curiosity had already discovered organic molecules on Mars, but with a smaller set of elements.
For methane, the existence of which was already known in the atmosphere of Mars, seasonal variations were discovered during almost three Martian years. This represents the equivalent of six years on Earth. It is the first time that such a repeatable phenomenon for methane has been identified.
Still, again, NASA is cautious. If the possibility of biological origins is not excluded at this stage, " water and rock chemistry may have produced methane. "
Signs of life on Mars formerly or present are still far from being established.