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Nasa probes oxygen mystery on Mars 

    The oxygen in Martian air is changing in a way that can't currently be explained by known chemical processes. That's the claim of scientists working on the Curiosity rover mission, who have been taking measurements of the gas.

    They discovered that the amount of oxygen in Martian "air" rose by 30% in spring and summer. The pattern remains a mystery, but researchers are beginning to narrow the possibilities.

    While the changes are most likely to be geological in nature, planetary scientists can't completely rule out an explanation involving microbial life.

    The results come from nearly six Earth years' (three Martian years') worth of data from the Sample Analysis at Mars (Sam) instrument, a portable chemistry lab in the belly of the Curiosity rover.

    The scientists measured seasonal changes in gases that fill the air directly above the surface of Gale Crater on Mars, where Curiosity landed. They have published their findings in the journal JGR-Planets.

(Adapted from: https://www.bbc.com/news/science-environment-50419917)