A dust storm and the onset of Martian winter have brought the Phoenix Mars Lander's mission to an end, NASA announced Monday. The lander's solar panel and robotic arm with a sample in its scoop are seen in this June 2008 image.  "We are actually ceasing operations, declaring an end to mission operations at this point," project manager Barry Goldstein with NASA's Jet Propulsion Laboratory told reporters in a teleconference.

Mission controllers last heard from the vehicle on November 2. Despite ongoing efforts to re-establish contact using NASA satellites in orbit around Mars, the spacecraft is silent. "We'll constantly turn on the radio and try to hail Phoenix to see if it is alive, but at this point nobody on the team has any expectations of that happening," Goldstein said. "But we do hope the vehicle will surprise us once again."

The Phoenix team knew when it selected a landing site on Mars' arctic plain that the spacecraft would not survive a winter there. But researchers picked it anyway because satellite observations indicated vast quantities of frozen water were in that area, most likely in the form of permafrost. They thought such a location would be a promising place to look for organic chemicals that would signal a habitable environment.

Phoenix landed on May 25, mid-summer in the Martian year  and conducted five months of research, scooping up soil samples for analysis in onboard scientific instruments. The sun never sets on the arctic region during the summer, so the solar-powered craft had plenty of power for the first few months of its mission.