The first images from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft show a planet in the process of losing parts of itself. Streams of hydrogen atoms drift away from the red planet, into the depths of space.
The pictures are the first clear look at how crucial elements erode away from the Martian atmosphere, says Bruce Jakosky, a planetary scientist at the University of Colorado Boulder and the mission’s principal investigator. MAVEN’s goal is to measure how the solar wind and other factors nibble away at Mars’s atmosphere, so that scientists can better extrapolate how the once-thick atmosphere has thinned over billions of years. That process transformed Mars from a relatively warm, wet planet into a mostly dry, mostly frozen wasteland.
MAVEN began orbiting Mars on September 21. The newly released images, from the craft's ultraviolet spectrograph, were taken while it was still relatively far from the planet, completing an elliptical orbit around Mars about once every 35 hours.
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Hydrogen appears to be leaving the planet's atmosphere in clumps and streams that reach about 10 Mars radii into space, said Mike Chaffin, a MAVEN scientist also at the University of Colorado, who discussed the results at a October 14news briefing. The hydrogen comes from water vapour that breaks apart in the upper atmosphere; because hydrogen is so much lighter than oxygen, it escapes into space relatively easily.
“That’s effectively removing water from the Martian atmosphere,” says Chaffin.
Other images show oxygen and carbon drifting away from the planet, although these heavier atoms cluster closer to Mars than hydrogen. Deep within the atmosphere, oxygen forms ozone molecules that accumulate near Mars’s south pole.
Since the pictures were taken, MAVEN has tightened its orbit and now circles Mars once every 4.6 hours. That vantage point will give it a more detailed look at how volatile substances are escaping from the atmosphere. But the craft will have a harder time seeing whether they might be traveling great distances from the planet.
Later this week, MAVEN will swivel its view away from Mars to take pictures of Comet Siding Spring, which is due to blow past Mars on October 19. MAVEN will also image the Martian atmosphere several days before and after the comet’s passage. Like other spacecraft currently orbiting Mars, it will shelter behind the planet when the comet gets closest, to protect itself from the cloud of dust that could rush in at speeds of 56 kilometers per second.
This article is reproduced with permission and was first published on October 14, 2014.
