Scientists Hazy on Mars Plume

High altitude plumes seen over Mars — Top in yellow circle (south is up) together with some different views of the changing plume. Image by W. Jaeschke and D. Parker on 21 March 2012.

Scientists have been looking into the cause of a huge plume high above the surface of Mars.

Amateur astronomers first noticed the vast plume back in 2012, when it appeared in March and April before disappearing. They were bright and at extremely high altitude.

Now scientists have had some time to go over the images and according to a paper published in Nature they formed within a few hours and lasted around 10 days. The plumes were 500-1000km across and showed some daily cyclic behaviour.

Mars Plume Animated Gif — Observations of a mysterious plume-like feature (marked with yellow arrow) at the limb of the Red Planet on 20 March 2012. The observation was made by astronomer W. Jaeschke. The image is shown with the north pole towards the bottom and the south pole to the top. Copyright: W. Jaeschke

Agustin Sanchez-Lavega of the Universidad del País Vasco in Spain, lead author of the paper, suggest the plumes could be particles of CO2 ice or H20 ice reflecting solar radiation, but far above the 100km region where clouds usually form. An alternative explantion is that there is an aurora over a region with an anomaly in the crustal magnetic field, though about 1000 times that of the Earth’s own aurora.

This similar plume was spotted on 17 May 1997 by the Hubble Space Telescope, though it was in a different location.

The scientists conclude that both the possible explanations for the plume "defy our current understanding of Mars’ upper atmosphere."

ESA's ExoMars Trace Gas Orbiter is due to launch in 2016, when it reaches Mars the scientists hope to shed further light on the plumes.