EXPOSURES OF WATER ICE IN THE NORTHERN MID-LATITUDES OF MARS.
C. C. Allen1 and L. C. Kanner2 1NASA Johnson Space Center, Houston, TX 77058 ****@nasa.gov 2Brown University, Providence, RI 02912 ****@brown.edu
Seventh International Conference on Mars.
"HiRISE images of the northern plains are showing
unprecedented details of the polygonal cracks. These
images also have the potential to reveal ejecta
morphologies around the small bright spots. Future
HiRISE images that include bright spots, compared to
MOC images taken years earlier, will illustrate the
temporal stability of the spots.
The MRO CRISM spectrometer, with multiple
spectral bands and a spatial resolution around 20 m,
should allow mineralogical identification of the
material exposed in the polygonal bounding cracks and
in the bright spots. These data may conclusively
demonstrate whether these features are composed of
ice, salt, or a mixture of both.
The Phoenix lander – scheduled for launch in
August, 2007 – will likely be targeted to a region of
small (~ 10 m diameter) polygons, bordered by bright
cracks, in the northern plains. This lander could
collect samples of material in these cracks and provide
detailed chemical analyses."
http://www.lpi.usra.edu/meetings/7thmars2007/pdf/3065.pdf

Polygonal cracks occur either in desiccated mud or permafrost terrain.
In either case it usually occurs in young terrain. This might be a good
place to search for recent aqueous minerals.

Bob Clark