CNN) -- A dust storm and the onset of Martian winter have brought the Phoenix Mars Lander's mission to an end, NASA announced Monday.
"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.
But a recent dust storm obscured the sunlight, and temperatures have dropped in recent weeks as the nights got longer and winter weather set in. The combination has caused the lander's batteries to drain.
"The situation we have experienced over the course of the last two weeks is exactly play-by-play what we had actually anticipated, although it was expedited by about three weeks by the dust storm," Goldstein said.
In the coming weeks, the sun will set for the season, and the long night of a polar winter will begin. Snow and advancing polar ice eventually will cover Phoenix.
Mission managers say they will attempt to reactivate Phoenix after next spring's thaw, but they caution it's extremely unlikely such efforts would be successful.
Over the course of the mission, scientists have learned a lot about the chemistry of the soil around the lander. They say it has a clumpy, clay-like consistency and is chocked full of salts. It also contains chemicals called perchlorates, which are toxic to humans but conceivably could be used as an energy source by certain microbes.
So far, researchers have not found the organic chemicals they were seeking, but say they intend to keep analyzing their data.
"I'm still holding out hope here," said Phoenix principal investigator Peter Smith, of the University of Arizona. "It's really a question of what is the truth on Mars, and we're trying to make sure we get the right answer here and not come rushing out with a quick analysis. This is really tricky stuff."
NASA's next mission to the planet is the Mars Science Laboratory, a large, nuclear-powered rover designed to traverse long distances with a suite of onboard scientific instruments. It is scheduled to launch next summer, though ongoing technical problems may require a postponement to 2011.
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