The end seems to have finally come for NASA's Phoenix Mars Lander mission at the planet's north pole, scientists said Monday.

"At this time we're pretty convinced that the vehicle is no longer available for us to use," said Phoenix project manager Barry Goldstein of NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Mission controllers lost touch with the lander on Nov. 2.

That "was actually the last time we actually heard form Phoenix," Goldstein said.

The spacecraft has been studying the arctic surface of the red planet for just over five months, since landing there May 25.

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During the course of its mission, Phoenix scooped up samples of the Martian dirt and subsurface water ice at its arctic landing site and analyzed them for signs of the planet's past potential habitability.

Phoenix touched down on the northern plains of a region of Mars known as Vastitas Borealis. The area is at a latitude on Mars equivalent to northern Alaska on Earth.

The lander's power supplies -- it gets its electricity from solar panels -- have been steadily diminishing in recent weeks as the sun dips toward the horizon with the approach of fall and winter to Mars' northern hemisphere.

Phoenix went into its inactive safe mode briefly on Oct. 28, then restarted once the sun came up the following day.

Phoenix would lose power or "brown out" at night, then wake up again when sunlight hit its solar arrays the next morning.

Mission engineers tried to turn off any unnecessary instruments and heaters to keep the batteries alive, but "we were unsuccessful in keeping the batteries from browning out," Goldstein said.

Phoenix has effectively ended all science operations, though the team will keep listening for any signals from the spacecraft relayed through the Mars orbiters.

Mission engineers had originally hoped the lander would last through the end of November, acting as a weather station and using its camera to photograph the change of season.

Though no one on the team expects that Phoenix will once again live up to its name and rise again, there's always the "hope that the vehicle will surprise us again," Goldstein said.

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