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Title: Scientists Have Clear Evidence of Martian Atmosphere 'Sputtering'

Link: https://science.slashdot.org/story/25/05/30/0...

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.

Read more of this story at Slashdot.

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