Scientists Have Clear Evidence of Martian Atmosphere 'Sputtering'

For the first time, scientists have directly observed atmospheric sputtering in action on Mars -- an erosion process driven by solar wind ions that may have played a major role in the planet's atmospheric and water loss. ScienceAlert reports: The only spacecraft with the equipment and orbital configuration to make these observations is NASA's MAVEN. The researchers carefully pored over the data collected by the spacecraft since it arrived in Mars orbit in September 2014, looking to find simultaneous observations of the solar electric field and an upper atmosphere abundance of argon -- one of the sputtered particles, used as a tracer for the phenomenon. They found that, above an altitude of 350 kilometers (217 miles), argon densities vary depending on the orientation of the solar wind electric field, compared to argon densities at lower altitudes that remain consistent.

The results showed that lighter isotopes of argon vary, leaving behind an excess of heavy argon -- a discrepancy that is best explained by active sputtering. This is supported by observations of a solar storm, the outflows of which arrived at Mars in January 2016. During this time, the evidence of sputtering became significantly more pronounced. Not only does this support the team's finding that argon density variations at high Martian altitudes are the result of sputtering, it demonstrates what conditions may have been like billions of years ago, when the Sun was younger and rowdier, undergoing more frequent storm activity. The findings have been published in the journal Science Advances.

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