Orbiter reveals clues about loss of atmosphere on Mars

Mars may once have supported life but is now a cold, dry planet, and scientists said Thursday that a stormy sun likely accelerated the loss of its atmosphere.

In fact, researchers believe the thick, protective atmosphere that allowed ancient Mars to be warm and wet billions of years ago may have disappeared far earlier in its history than previously thought.

Data from MAVEN, an unmanned spacecraft that has been circling Mars for the past year, was published in scientific studies, including four in the journal Science and 44 more in Geophysical Research Letters.

Instruments aboard the spacecraft are measuring ions in the upper atmosphere of Mars and are also keeping track of solar wind to help understand what influences the escape of gas to space.

"The key findings that we are publishing this week all relate to how escape occurs and how much escape is occurring today," lead researcher Bruce Jakosky said in a podcast interview with Science magazine.

"What we are finding is that the rate of loss out the top is relatively slow today, maybe only about 100 grams per second globally, but over time that can be a significant loss," he said.

"And we think that that is the tip of the iceberg so to speak, that early in history the loss rates were much greater and that this mechanism could account for the loss of a very thick early atmosphere."

Caption: Representative Image

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