Mars' upper atmosphere has been gradually disappearing for millions of yearsNASA's latest probe, the Mars Atmosphere and Volatile Evolution (MAVEN), has just started sending back data from the upper atmosphere of Mars, analyzing it's makeup of hydrogen, carbon, and oxygen, and how these molecules are changing over time in the planet's atmosphere
The results will teach us why Mars' atmosphere is so thin compared to Earth's and why what was once a planet that could have sustained life is now so cold, dry, and barren
MAVEN went into orbit around Mars on Sep. 21 and in its three weeks around the planet, the spacecraft has already given NASA researchers an unprecedented look at the Martian atmosphere. Our first taste of the results has just come back, NASA scientists announced at a press conference on Oct. 14
Today, Mars' atmosphere is pretty thin. But early on in the planet's life, scientists suspect that Mars had a thicker atmosphere, higher surface temperatures, and therefore could harbor liquid water and possibly life. But something happened starting about 3.7 billion years ago, that's left Mars with the atmosphere it has today
Why the Red Planet's atmosphere has whittled away to almost nothing is a mystery that the MAVEN team is trying to solve by looking at how water and carbon dioxide molecules disassociate into their individual hydrogen, oxygen, and carbon atomic components.
Some of these atoms escape the Martian atmosphere, and so by looking at their abundance in the lower and upper atmosphere — and how that changes with time — scientists can get a better idea of what's causing these elements to separate from their parent molecules and escape into space.Hydrogen
"This is the best picture [shown below] ever made of atomic hydrogen in the extended upper atmosphere of Mars," Mike Chaffin, MAVEN Remote Sensing Team member at the University of Colorado, Boulder, said during the NASA press conference. "It's an important measurement to make because the hydrogen we're looking at here comes from water lower down in the atmosphere."
This water has broken apart into its atomic components, hydrogen and oxygen, and once hydrogen reaches the upper atmosphere of Mars it escapes into space because it is extremely light and so is weakly bound by Mars' gravity. It's escape processes like these that remove water from Mars, Chaffin explained, and may have "dominated the history of Martian climate change."
The hydrogen slipping away from the planet is shown by the bright white band around the red circle, which marks the outline of Mars. The band is bright because the hydrogen atoms are reflecting the sunlight that is shining on the day-side half of Mars.