NASA calls it quits on damaged Phoenix lander

NASA gave the Phoenix lander a final chance to phone home last week, but the craft's continuing silence and a new image showing ice damage to its solar panels have forced the space agency to give up hope on the mission.

The HiRISE camera aboard the Mars Reconnaissance Orbiter captured these images of Phoenix in 2008 and 2010. The recent image on the right shows a shadow from Phoenix's lander body and eastern solar panel, but no shadow cast by the craft's western solar panel. Credit: NASA/JPL-Caltech/University of Arizona

Phoenix landed in the Martian arctic two years ago this week, successfully accomplishing its primary three-month mission and two bonus months of operations before succumbing to the polar winter in November 2008.

The Mars Odyssey orbiter flew over the Phoenix landing site 61 times last week. Odyssey was listening for radio signals from the spacecraft that would indicate it had re-awakened after a winter slumber.

But Odyssey heard no signals from Phoenix, NASA announced Monday. Three other campaigns since January also failed to communicate with the lander.

Phoenix was not designed to survive winter near the Martian north pole, where the sun slips below the horizon for months and sheets of carbon dioxide ice encrust the soil. Before this spring's communications passes, NASA officials held onto a sliver of hope the lander would survive the winter and wake up as the sun rose above the horizon.

A new image of Phoenix snapped by the Mars Reconnaissance Orbiter's high-resolution HiRISE mapping camera shows one of the lander's two circular solar panels could have snapped off after several hundred pounds of ice built up on the structure.

The craft's shadow is smaller than in pictures taken from orbit during its operational mission in 2008.

"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."

Before the onset of winter, mission officials predicted the weight of ice on Phoenix could cause its solar panels to bend or break.

Phoenix collected this mosaic of one of the lander's solar panels in 2008. Credit: NASA/JPL-Caltech/University of Arizona/Texas A&M University

During its five-month mission, the lander dug trenches with a robot arm and studied patches of water ice just a few inches below the surface of Mars.

"The Phoenix spacecraft succeeded in its investigations and exceeded its planned lifetime," said Fuk Li, manager of Mars programs at the 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."

Phoenix also discovered evidence of occasional thawed water at the landing site, and the mission found a chemical called perchlorate, which set off speculation about the Red Planet's habitability in its ancient past. Perchlorates are toxic to some organisms and provide food for other species on Earth, and its discovery sent a mixed message to scientists trying to determine whether life ever existed on Mars.

"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."