After five fruitful months experiments, Nasa's Phoenix Mars Lander programme was finally declared dead as Martian winter and a raging dust storm appeared to have drained the probe's batteries. Landing on the Red Planet on 25 May this year the Phoenix is now believed to have sent its last signals to earth, said NASA scientists who announced the end of the mission Monday.
NASA scientists have not heard anything from the Lander since 2 November.
Scientists said there was a slight chance that the Lander's energy-saving "Lazarus mode" could allow Phoenix to come alive again after the long Martian winter, though with limited capacity. They said the craft could have survived till December, but frigid temperatures and lack of sunlight, largely due to a dust storm, were draining the probe's solar-powered batteries.
"At this time, we're pretty convinced that the vehicle is no longer is available for us to use," said Doug McCuistion, director of NASA's Mars Exploration Program.
Launched in August 2007, the Phoenix Mars Mission was designed to explore the presence of water and life, in the form of micro-organisms, in the ice-rich soil near the planet's north pole.
Scientists said the mission accomplished "99 percent of what we proposed to do."
According to Principal Investigator, Peter Smith, of the University of Arizona, the lander exceeded expectations overall. The mission was to last 90 sols, or Martian days, which are 24 hours and 39 minutes each. The Phoenix stopped communicating after 150 sols.
Using a colourful analogy McCuistion said, "It's really an Irish wake, rather than a funeral."He added, "We should celebrate what Phoenix has done and what the team has done."
The lander confirmed what scientists had surmised from data sent by an earlier Mars mission, the Odyssey orbiter- that there was ice just under the red planet's surface.
According to Peter Smith, Phoenix had uncovered alkaline soil and "a whole suite of nutrients-the kinds of things you take in your vitamin pill." This indicated that water also evaporates on the Martian surface.
Phoenix also found perchlorate, which is used by microbes on earth as an energy source.
A weather station aboard the craft reported frost on the ground and snow falling from Martian clouds.
Operating in its "Lazarus mode," the craft was still operating for about two hours each day transmitting to the orbiters that relay Phoenix's data to Earth. It would then rest, recharging its batteries from the sunlight.
Without battery power for the heaters, the spacecraft must weather temperatures near minus 220 degrees Fahrenheit (minus 140 degrees Celsius) for six months of Martian winter, Smith said. It is also possible that carbon dioxide ice could destroy or bury the solar panels, killing Phoenix's ability to recharge.
However there is faint hope that the same Lazarus programming that allowed Phoenix to take advantage of waning Martian sunlight to transmit for two hours each day could also allow it to come back alive in the Martian spring..
"There is a possibility that it could try to come alive and contact us again. The chances are probably low," NASA's McCuistion said.
If it should come alive NASA may like to keep using it as a Martian weather station.
Dead, it would still retain a DVD time capsule with it. The Visions of Mars DVD, developed by the Planetary Society in Pasadena, California, is made of silica glass, for durability. It contains the names of about 250,000 people from more than 70 countries, as well as samples of earth literature, art, and music.
Summing up the mission, Univ of Arizona's Peter Smith said, "What we're looking for, of course, is a habitable zone on Mars. I think we have the data that's going to show that."