News : NASA loses contact with Mars lander, ends mission

By Dan Whitcomb

LOS ANGELES (Reuters) - The Phoenix Mars Lander, which made history by finding definitive proof of water on the Red Planet, has lost contact with Earth, effectively ending its more than five-month mission, NASA said on Monday.

The robotic probe had been expected to stop communicating with its Earth-bound handlers as it slowly froze to death with the onset of Martian winter, but its sudden end came after a dust storm cut off even more energy-giving sunlight from the spacecraft.

Phoenix, which touched down at the north pole of Mars in late May, transmitted its last signal to Earth on November 2 and project scientists said they would try for three more weeks to contact the lander, but considered the $475 million mission essentially over.

"We are actually ceasing operations, declaring an end to operations at this point," Barry Goldstein, Phoenix mission project manager at NASA's Jet Propulsion Laboratory in Pasadena, California, told reporters at a briefing.

"We'll constantly turn on the radio and try to hail Phoenix and see if it's alive, but at this point nobody on the team has any expectations of that happening," he said.

Conceived in 2002 and launched in August 2007, the spacecraft touched down on May 25 on a frozen Martian desert to search for water and assess conditions for the possibility of sustaining life.

STILL SEARCHING FOR LIFE

Phoenix has since recorded snowfall, scraped up bits of ice and found that Martian dust chemically resembled seawater on Earth -- adding to evidence that liquid water capable perhaps of supporting life once flowed on the planet's surface.

In July, NASA scientists announced that Phoenix had "touched and tasted" water on the surface of Mars, containing years of speculation about the existence of water on the planet.

The probe also returned more than 25,000 pictures.

By late October, Phoenix had surpassed its expected operational lifetime by two months. Mission controllers shut down some of the lander's heaters and instruments last month to conserve its energy.

Phoenix was only the sixth space probe to land successfully on Mars and the first spacecraft to touch down safely at one of the planet's polar regions.

The demise of Phoenix leaves NASA with two other functioning probes on the planet's surface -- the twin rovers Spirit and Opportunity, which arrived weeks apart in January 2004 to begin their own geologic expeditions. They, too, are well past their original three-month life expectancy.

Three satellite probes are orbiting the planet -- NASA's Mars Reconnaissance Orbiter and Mars Odyssey and the European Space Agency's Mars Express.

Phoenix principal investigator Peter Smith said his team must now pore over data sent back by the craft and could still find evidence of past or current life on Mars.

"I'm not sure we didn't find organics. We haven't analyzed the data yet. These are subtle signatures and until we actually do the work, I can't say we didn't find it," Smith said.

"I'm still holding out hope," he said. "Its really the question of what is the truth on Mars and we're trying to get the right answer here."

(Additional reporting by Steve Gorman; Editing by Peter Cooney)