Washington : NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has spotted a mysterious dust cloud and aurora around the “Red planet.” The presence of the dust at orbital altitudes from about 93 miles (150 kilometers) to 190 miles (300 kilometers) above the surface was not predicted. Although the source and composition of the dust are unknown, there is no hazard to MAVEN and other spacecraft orbiting Mars. The cloud was detected by the spacecraft’s Langmuir Probe and Waves (LPW) instrument, and has been present the whole time MAVEN has been in operation. It is unknown if the cloud is a temporary phenomenon or something long lasting.
The cloud density was greatest at lower altitudes. However, even in the densest areas it is still very thin. So far, no indication of its presence has been seen in observations from any of the other MAVEN instruments. Possible sources for the observed dust include dust wafted up from the atmosphere; dust coming from Phobos and Deimos, the two moons of Mars; dust moving in the solar wind away from the sun; or debris orbiting the sun from comets. However, no known process on Mars could explain the appearance of dust in the observed locations from any of these sources.
A map of IUVS’s auroral detections in December 2014 overlaid on Mars’ surface. The map showed that the aurora was widespread in the northern hemisphere, not tied to any geographic location. The aurora was detected in all observations during a 5-day period. MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) observed what scientists have named “Christmas lights.” For five days just before Dec. 25, MAVEN saw a bright ultraviolet auroral glow spanning Mars’ northern hemisphere. 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.