NASA's Mars MAVEN Mission Spots Link in Planet's Atmosphere Loss

These days, Mars doesn't have much in the way of an atmosphere. And yet it did in its ancient past. Now, NASA's newest Mars orbiter, MAVEN, has discovered key features about the loss of the planet's atmosphere to space over time.

MAVEN entered the science phase of its mission on Nov. 16. Since then, it's collected data and has shed a bit more light on the atmosphere of the Red Planet. On each orbit around Mars, MAVEN dips into the ionosphere, which is the layer of ions and electrons that extend about 75 to 300 miles above the surface of the planet. This layer serves as a type of shield around the planet, deflecting solar wind.

Surprisingly, MAVEN's Solar Wind Ion Analyzer has found a stream of solar-wind particles that are not deflected by the ionosphere. Instead, they penetrate deep into Mars' upper atmosphere. Interactions in the upper atmosphere transform this stream of ions into a neutral form that can penetrate to low altitudes. Then deep in the ionosphere, the stream emerges in ion form again. The reappearance of these ions provides a new way to track the properties of the solar wind and make it easier to link drivers of atmospheric loss directly to activity in the upper atmosphere and ionosphere.

"We are beginning to see the links in a chain that begins with solar-driven processes acting on gas in the upper atmosphere and leads to atmospheric loss," said Bruce Jakosky, MAVEN principal investigator, in a news release. "Over the course of the full mission, we'll be able to fill in this picture and really understand the processes by which the atmosphere changed over time."

MAVEN's Neutral Gas and Ion Mass Spectrometer is currently exploring the nature of the reservoir from which gases are escaping by conducting the first comprehensive analysis of the composition of the upper atmosphere and ionosphere. These studies, in particular, will reveal connections between the lower atmosphere and the upper atmosphere, where the loss is occurring.

The findings show a bit more about how atmosphere loss occurs over time. This, in turn, may tell scientists a bit more about ancient Mars, and whether or not live could have existed on the planet.

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