[meteorite-list] Mystery Mars Plume Baffles Scientists

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri, 20 Feb 2015 16:01:16 -0800 (PST)
Message-ID: <201502210001.t1L01GKK010474_at_zagami.jpl.nasa.gov>

http://www.esa.int/Our_Activities/Space_Science/Mystery_Mars_plume_baffles_scientists

Mystery Mars Plume Baffles Scientists
European Space Agency
16 February 2015

Plumes seen reaching high above the surface of Mars are causing a stir
among scientists studying the atmosphere on the Red Planet.

On two separate occasions in March and April 2012, amateur astronomers
reported definite plume-like features developing on the planet.

The plumes were seen rising to altitudes of over 250 km above the same
region of Mars on both occasions. By comparison, similar features seen
in the past have not exceeded 100 km.

"At about 250 km, the division between the atmosphere and outer space
is very thin, so the reported plumes are extremely unexpected," says Agustin
Sanchez-Lavega of the Universidad del Pais Vasco in Spain, lead author
of the paper reporting the results in the journal Nature.

[Image]
High-altitude plume on Mars

The features developed in less than 10 hours, covering an area of up to
1000 x 500 km, and remained visible for around 10 days, changing their
structure from day to day.

None of the spacecraft orbiting Mars saw the features because of their
viewing geometries and illumination conditions at the time.

However, checking archived Hubble Space Telescope images taken between
1995 and 1999 and of databases of amateur images spanning 2001 to 2014
revealed occasional clouds at the limb of Mars, albeit usually only up
to 100 km in altitude.

But one set of Hubble images from 17 May 1997 revealed an abnormally high
plume, similar to that spotted by the amateur astronomers in 2012.

Scientists are now working on determining the nature and cause of the
plumes by using the Hubble data in combination with the images taken by
amateurs.

"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," says Agustin.

"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," adds Antonio Garcia Munoz, a research fellow at ESA's
ESTEC and co-author of the study.

The jury is still out on the nature and genesis of these curious high-altitude
martian plumes. Further insights should be possible following the arrival
of ESA's ExoMars Trace Gas Orbiter at the Red Planet, scheduled for launch
in 2016.

         
Notes for Editors

"An extremely high altitude plume seen at Mars morning terminator," by
A. Sanchez-Lavega et al. is published in the 16 February 2015 issue of
the journal Nature.

The ground-based images were provided by astronomers W. Jaeschke, D. Parker,
J. Phillips and D. Peach.

For further information, please contact:

Markus Bauer
ESA Science and Robotic Exploration Communication Officer
Tel: +31 71 565 6799
Mob: +31 61 594 3 954
Email: markus.bauer at esa.int

Agustin Sanchez-Lavega
Universidad del Pais Vasco UPV/EHU
Email: agustin.sanchez at ehu.es
Received on Fri 20 Feb 2015 07:01:16 PM PST