May 25, 2010: 
Two images of the Phoenix Mars lander taken from Martian orbit in 2008 and 2010. The 2008 lander image shows two relatively blue spots on either side corresponding to the spacecraft's clean circular solar panels. In the 2010 image scientists see a dark shadow that could be the lander body and eastern solar panel, but no shadow from the western solar panel. Image credit: NASA/JPL-Caltech/University of Arizona
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NASA's Phoenix Mars Lander has ended operations
after repeated attempts to contact the spacecraft were unsuccessful.
A new image transmitted by NASA's Mars Reconnaissance Orbiter (MRO)
shows signs of severe ice damage to the lander's solar panels.
"The Phoenix spacecraft succeeded in its investigations and exceeded
its planned lifetime, " said Fuk Li, manager of the Mars Exploration
Program at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"Although its work is finished, analysis of information from
Phoenix's science activities will continue for some time to come."
Last week, NASA's Mars Odyssey orbiter flew over the Phoenix landing
site 61 times during a final attempt to communicate with the lander.
No transmission from the lander was detected. Phoenix also did not
communicate during 150 flights in three earlier listening campaigns
this year.
Earth-based research continues on discoveries Phoenix made during
summer conditions at the far-northern site where it landed May 25,
2008. The solar-powered lander completed its three-month mission and
kept working until sunlight waned two months later.
Phoenix was not designed to survive the dark, cold, icy winter.
However, the slim possibility Phoenix survived could not be
eliminated without listening for the lander after abundant sunshine
returned.
The MRO image of Phoenix taken this month by the High Resolution
Imaging Science Experiment, or HiRISE, camera on board the spacecraft
suggests the lander no longer casts shadows the way it did during its
working lifetime.
"Before and after images are dramatically different, " said Michael
Mellon of the University of Colorado in Boulder, a science team
member for both Phoenix and HiRISE. "The lander looks smaller, and
only a portion of the difference can be explained by accumulation of
dust on the lander, which makes its surfaces less distinguishable
from surrounding ground."
Apparent changes in the shadows cast by the lander are consistent with
predictions of how Phoenix could be damaged by harsh winter
conditions. It was anticipated that the weight of a carbon-dioxide
ice buildup could bend or break the lander's solar panels. Mellon
calculated hundreds of pounds of ice probably coated the lander in
mid-winter.
During its mission, Phoenix confirmed and examined patches of the
widespread deposits of underground water ice detected by Odyssey and
identified a mineral called calcium carbonate that suggested
occasional presence of thawed water. The lander also found soil
chemistry with significant implications for life and observed falling
snow. The mission's biggest surprise was the discovery of
perchlorate, an oxidizing chemical on Earth that is food for some
microbes and potentially toxic for others.
"We found that the soil above the ice can act like a sponge, with
perchlorate scavenging water from the atmosphere and holding on to
it, " said Peter Smith, Phoenix principal investigator at the
University of Arizona in Tucson. "You can have a thin film layer of
water capable of being a habitable environment. A micro-world at the
scale of grains of soil -- that's where the action is."
The perchlorate results are shaping subsequent astrobiology research,
as scientists investigate the implications of its antifreeze
properties and potential use as an energy source by microbes.
Discovery of the ice in the uppermost soil by Odyssey pointed the way
for Phoenix. More recently, the MRO detected numerous ice deposits in
middle latitudes at greater depth using radar and exposed on the
surface by fresh impact craters.
"Ice-rich environments are an even bigger part of the planet than we
thought, " Smith said. "Somewhere in that vast region there are going
to be places that are more habitable than others."
NASA's MRO reached the planet in 2006 to begin a two-year primary
science mission. Its data show Mars had diverse wet environments at
many locations for differing durations during the planet's history,
and climate-change cycles persist into the present era. The mission
has returned more planetary data than all other Mars missions
combined.
Odyssey has been orbiting Mars since 2001. The mission also has played
important roles by supporting the twin Mars rovers Spirit and
Opportunity. The Phoenix mission was led by Smith at the University
of Arizona, with project management at JPL and development
partnership at Lockheed Martin in Denver. The University of Arizona
operates the HiRISE camera, which was built by Ball Aerospace and
Technologies Corp., in Boulder. Mars missions are managed by JPL for
NASA's Mars Exploration Program at NASA Headquarters in Washington.
Phoenix information and images.
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