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18 March 2015

Weird aurora and dust cloud found on new Mars mission

Weird aurora and dust cloud found on new Mars mission

(Image: University of Colorado)

NASA’s MAVEN spacecraft celebrated its first Christmas orbiting Mars by watching an unusual aurora penetrating deep into the planet’s atmosphere, mission scientists revealed today. The probe has also encountered an unexpected high-altitude dust cloud, which so far defies explanation but may be linked to another recent cloud-like object hovering high over Mars.

Bruce Jakosky, who leads the mission, presented early results from the MAVEN mission at the Lunar and Planetary Science conference in The Woodlands, Texas today, along with other colleagues working on the mission. “The data is just spectacular,” he told the conference.

One surprising find was an aurora unlike any seen on Mars before. Auroras on Earth are created when charged particles from the sun are attracted by the planet’s magnetosphere and ionise the atmosphere, creating a spectacular light show. Mars has a very weak and patchy magnetosphere, so previous auroras seen on Mars were over areas in the southern hemisphere where the magnetic field is strongest.


Mysterious glow



MAVEN has also found an unexpected dust cloud between altitudes of 150 and 300 kilometres. The spacecraft first saw the dust while preparing for its encounter with a comet that just happened to approach close to Mars in October , shortly after MAVEN reached the planet. “We were looking for dust from the comet Siding Spring so we wanted to get a baseline,” said Laila Andersson, who is in charge of the Langmuir Probe and Waves instrument on MAVEN that spotted the dust.

A cloud over the mission

In the end MAVEN didn’t see an increase in dust when the comet flew past, but it did detect a cloud which has persisted the entire time the spacecraft has been operating. The intensity of the cloud seems to fluctuate over time and is mostly present on the day side of the planet.

The dust could be falling down from the planet’s two moons, Phobos and Deimos, or be linked to dust in the solar wind or comets orbiting the sun, but none of these explanations seem to fit the particular pattern of MAVEN’s observations. Jakosky says they are planning a flyby of Phobos and will look to see if dust is falling down.

Andersson thinks it could instead be wafting up from the lower atmosphere, but it isn’t clear how that would happen either. “We have no process to take dust from low altitude to bring it up to 200 kilometres,” she said.

At present the dust poses no threat to MAVEN or other spacecraft operating around Mars, but it could be linked to a much larger dust plume spotted by amateur astronomers in 2012, which seemed to reach from the surface up to an altitude of 250 kilometres. This was in the southern hemisphere, whereas MAVEN is currently in the north, but it will head south in the future.

If a dust plume happens to occur while MAVEN is in the area, the spacecraft could fly through it, putting it in danger. “I wouldn’t want to but it may happen,” says Jakosky, but he’s not too worried about the potential for this rare occurrence. “There are enough things to worry about that I can effect, my sleep is shot on this mission.”