November 7th, 2009

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Frost on the Phoenix

I enjoyed this piece of space news:


Frost-Covered Phoenix Lander Seen in Winter Images

The full version of this story with accompanying images is
at: http://www.jpl.nasa.gov/news/news.cfm?release=2009-160

PASADENA, Calif. -- Winter images of NASA's Phoenix Lander showing the
lander shrouded in dry-ice frost on Mars have been captured with the
High
Resolution Imaging Science Experiment, or HiRISE camera, aboard NASA's
Mars Reconnaissance Orbiter.

The HiRISE camera team at the University of Arizona, Tucson, captured
one
image of the Phoenix lander on July 30, 2009, and the other on Aug. 22,
2009. That's when the sun began peeking over the horizon of the northern
polar plains during winter, the imaging team said. The first day of
spring in the northern hemisphere began Oct. 26.

The images are available at
http://hirise.lpl.arizona.edu/ESP_014393_2485
.

"We decided to try imaging the site despite the low light levels," said
HiRISE team member Ingrid Spitale of the University of Arizona Lunar and
Planetary Laboratory.

"The power of the HiRISE camera helped us see it even under these poor
light conditions," added HiRISE team member Michael Mellon of the
University of Colorado in Boulder, who was also on the Phoenix Mars
Lander science team.

The HiRISE team targeted their camera at the known location of the
lander
to get the new images and compared them to a HiRISE image of the
frost-free lander taken in June 2008. That enabled them to identify the
hardware disguised by frost, despite the fact that their views were
hindered by poor lighting and by atmospheric haze, which often obscures
the surface at this location and season.

Carbon dioxide frost completely blankets the surface in both images. The
amount of carbon dioxide frost builds as late winter transitions to
early
spring, so the layer of frost is thicker in the Aug. 22 image.

HiRISE scientists noted that brightness doesn't necessarily indicate the
amount of frost seen in the images because of the way the images are
processed to produce optimal contrast. Even the darker areas in the
frost-covered images are still brighter than typical soil that surrounds
the lander in frost-free images taken during the lander's prime mission
in 2008.

Other factors that affect the relative brightness include the size of
the
individual grains of carbon dioxide ice, the amount of dust mixed with
the ice, the amount of sunlight hitting the surface and different
lighting angles and slopes, Spitale and Mellon said.

Studying these changes will help us understand the nature of the
seasonal
frost and winter weather patterns in this area of Mars.

Scientists predicted that the ice layer would reach maximum thickness in
September 2009, but don't have images to confirm that because HiRISE
camera operations were suspended when Mars Reconnaissance Orbiter
entered
an extended safe mode on Aug. 26.

The Phoenix Mars Lander ceased communications last November, after
successfully completing its mission and returning unprecedented primary
science phase and returning science data to Earth. During the first
quarter of 2010, teams at JPL will listen to see if Phoenix is still
able
to communicate with Earth. Communication is not expected and is
considered highly unlikely following the extended period of frost on the
lander.

HiRISE is run from the Lunar and Planetary Laboratory's HiRISE
Operations
Center, on the University of Arizona campus. Planetary Sciences
Professor
Alfred McEwen is HiRISE principal investigator. Planetary Sciences
Professor Peter Smith is principal investigator for the Phoenix Mars
Lander mission. The Mars Reconnaissance Orbiter is managed by NASA's Jet
Propulsion Laboratory, a division of the California Institute of
Technology, for NASA Science Mission Directorate, Washington. Lockheed
Martin Space Systems, based in Denver, is the prime contractor and built
the spacecraft. Ball Aerospace Technologies Corp., of Boulder, Colo.,
built the HiRISE camera.

For more information about the mission, visit: http://www.nasa.gov/mro .