Mystery Plumes Spotted on Mars

Posted on February 16, 2015

Mystery plumes have been spotted on Mars that reach high above the surface of the planet. The plumes were spotted in March 2012 and April 2012. The plumes rose to altitudes over 250 kilometers (150 miles) each time. The image above is from March 2012. The plumes lasted for about ten days.

Agustin Sanchez-Lavega of the Universidad del PaĆ­s Vasco in Spain is the lead of author of a research paper on the plumes published in Nature. Sanches-Lavega says, "At about 250 km, the division between the atmosphere and outer space is very thin, so the reported plumes are extremely unexpected."

The plumes were picked up by Hubble and can be seen in several archived images including one from 1997. The plume below is from a May 17, 1997 Hubble image. The spacecraft orbiting Mars were not in the right location to observe the plumes. Astronomers do not yet know what the plumes consist of or what is causing them. Theories include clouds of water-ice or carbon dioxide ice or something related to an auroral emission.

Sanchez-Lavega says, "One idea we've discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes."

Antonio Garcia Munoz, a research fellow at ESA's ESTEC and co-author of the study, says, "Another idea is that they are related to an auroral emission, and indeed auroras have been previously observed at these locations, linked to a known region on the surface where there is a large anomaly in the crustal magnetic field."

The authors say in the Nature paper that both the clouds of ice particles and the aurora emission explanations "defy our current understanding of Mars' upper atmosphere."

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