Scientists have uncovered evidence that Mars' atmosphere used to be much more dense than it is today. Currently, the red planet's atmosphere is extremely sparse, just 1% of the density of Earth's at sea level, but according to new research, that wasn't always true.
At the EGU 2013 General Assembly today in Vienna, researchers announced that NASA's Curiosity rover has found "strong" evidence that much of Mars' original atmosphere escaped into space a long time ago.
Curiosity's Sample Analysis at Mars (SAM) instrument analyzed a sample of the planet's atmosphere last week, the results of which provided our most accurate look at the isotopes of argon in the air. The findings showed that a light variant of argon has been more or less depleted in the atmosphere.
"We found arguably the clearest and most robust signature of atmospheric loss on Mars," said SAM co-investigator Sushil Atreya of the University of Michigan.
Scientists are saying that Mars most likely lost most of its original atmosphere when large amounts of gas escaped into space. This is because Mars has no global magnetic field to hold atoms and molecules in place, allowing them to be stripped from the upper atmosphere by solar wind.
"We've been seeing the same kind of behavior in the carbon dioxide isotopes and the water isotopes - they're all telling us the same story; that gases have been escaping from Mars over time, and the argon isotope just really nails it," Atreya added.
A thicker, more Earth-like atmosphere might have meant that Mars could have sustained bodies of water on the surface sometime in its past. This in turn might indicate that the red planet could have assisted in the development of life a long time ago.
Currently however, the air pressure is so low that any surface water would almost immediately boil away.
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