Mars Has Strange Planet-Wide Auroras, NASA Finds

Scientists publish the first data from MAVEN, NASA's newest Mars-orbiting probe.


The first round of official results are in from NASA's Mars Atmosphere and Volatile Evolution (MAVEN) probe, which launched in November 2013 arrived at Mars in September 2014 to study the Red Planet's mysterious atmosphere. One of the biggest surprises: planet-wide aurorae of an entirely different energy and composition than the Northern Lights you might see on Earth.

Preliminary results indicate that the loss of Mars' internal magnetic field played a role in the loss of its early atmosphere, as well as the unusual aurorae. That atmosphere was thick enough to support bodies of liquid water on the planet, but was stripped away billions of years ago, leaving a thin atmosphere of mostly carbon dioxide behind. 

"When the intrinsic field was large, Mars was losing less of its atmosphere," says Steve Bougher, lead author of the study and a professor at the University of Michigan. "Now that it's minimal or non-existent, ions and neutrals are being lost from the upper atmosphere."

"The auroras at the Earth are discrete. The ones at Mars are over a broad portion of planet."

The remains of the magnetic field are now in the surface of the planet, trapped within rocks, ice, and soil in the southern hemisphere of Mars, Bougher says. This crustal magnetic field plays a role in the aurorae on Mars. On Earth, aurorae occur when charged solar particles collide with our magnetic field, creating a relatively localized display of light. But without a global magnetic field, the aurorae on Mars take on a different form with different energies. It also disperses over a wider area, at times globally. 

"The auroras at the Earth are discrete—I mean, they're very localized," Bougher says. "The ones at Mars in some cases are diffuse or over a broad portion of planet." 

MAVEN orbits Mars in an unusual orbit that allows it to take periodic deep dips into the upper atmosphere, on the hunt for the culprit behind the escaping atmosphere of the planet, a process that began 3 billion years ago. These results from the first half-year on Mars were published in Science today in three papers, available herehere, and here

A more complete picture will come in the next few months, when MAVEN has the opportunity to study seasonal changes on Mars and find out how that interacts with the upper atmosphere of the planet. The MAVEN team is also waiting to see how massive dust storms affect the planet. The published research so far is what Bougher calls the "first taste" of what MAVEN can reveal about the planet.

"We've just about covered a half of Mars' year," he says. "The rest of Mars' year and the change of the solar output, we'll be able to piece things together in a more complete way."

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