NASA's MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft observed two unexplained occurrences in the Martian atmosphere: a high-altitude dust cloud and a deep-reaching aurora, according to a press release.
The dust, at altitudes between 93 miles (150 kilometers) and 190 miles (300 kilometers), was unexpected. The source and composition of the dust are unknown, but it doesn't seem to be a safety issue for MAVEN and other spacecraft.
"If the dust originates from the atmosphere, this suggests we are missing some fundamental process in the Martian atmosphere," said Laila Andersson of the University of Colorado's Laboratory for Atmospherics and Space Physics (CU LASP), according to the press release.
The cloud of dust was observed by the spacecraft's Langmuir Probe and Waves (LPW) instrument. Scientists speculate the dust came from the atmosphere, from the two moons of Mars (Phobos and Deimos), dust carried by solar wind or debris from comets.
MAVEN's Imaging Ultraviolet Spectrograph (IUVS) observed what scientists have named "Christmas lights." Aurora, known on Earth as northern or southern lights, are caused by energetic particles like electrons crashing down into the atmosphere and causing the gas to glow, according to the press release.
"What's especially surprising about the aurora we saw is how deep in the atmosphere it occurs -- much deeper than at Earth or elsewhere on Mars," said Arnaud Stiepen, IUVS team member at the University of Colorado, according to the press release. "The electrons producing it must be really energetic."
MAVEN was launched to Mars on Nov. 18, 2013, to find out how the Red Planet lost most of its atmosphere and much of its water. The spacecraft arrived at Mars on Sept. 21, 2014 and is four months into its primary mission slated to last for one Earth year.
"The MAVEN science instruments all are performing nominally, and the data coming out of the mission are excellent," said Bruce Jakosky of CU LASP, principal investigator for the mission, according to the press release.
