Solar winds are stripping the Martian atmosphere at 100g/s

6 Nov 2015

Artist’s rendering of a solar storm hitting Mars and stripping ions from the planet's upper atmosphere. Image via NASA/GSFC

New research has revealed that the rate at which solar winds have stripped Mars of its atmosphere has been slow but catastrophic for the ecology of the planet.

While current scientific understanding indicates that Mars once had a relatively thick atmosphere capable of supporting large volumes of liquid water, it was known that solar winds had bombarded the planet, leaving it as a desert-like wasteland.

What hadn’t been known, however, was the rate at which it has been stripped away, but now data from the Mars Atmosphere and Volatile Evolution (MAVEN) mission has revealed that that the solar wind strips away gas at a rate of about 100 grams every second.

This increases significantly during strong solar storms, most recently seen during the March 2015 solar storm.

NASA said the combination of greater loss rates and increased solar storms in the past suggests that loss of atmosphere to space was likely a major process in changing the Martian climate.

The bulk of the stripping of the atmosphere appears to be occurring in three particular regions: down the ‘tail’, where the solar wind flows behind Mars, above the Martian poles in a ‘polar plume’, and from an extended cloud of gas surrounding Mars.

“Like the theft of a few coins from a cash register every day, the loss becomes significant over time,” said Bruce Jakosky, MAVEN principal investigator. “We’ve seen that the atmospheric erosion increases significantly during solar storms, so we think the loss rate was much higher billions of years ago when the sun was young and more active.”

The region near the tail is, by far, the most significantly affected, accounting for 75pc of the atmosphere’s loss, with 25pc escaping from the plume region.

Coincidentally, yesterday saw further development of our understanding of the local winds on the Red Planet itself, with three Irish researchers creating a topographical model of how the sand dunes on Mars have evolved due to winds.

Their findings could play a key role in one day determining a site where future human missions to Mars could land.

Colm Gorey was a senior journalist with Silicon Republic