NASA is making one final effort to detect signs of life in the Mars Lander, which scientists fear has frozen to death on the surface of the Red Planet.
NASA's Mars Odyssey yesterday began sending out radio signals for a last time in the hopes that the robotic Lander will pick them up and respond. Through Friday, the orbiter will make 61 flights this week high over the Mars Lander's site on the Martian surface.
The robotic Mars Lander went silent in November 2008 after studying the Martian surface for five months.
This week marks NASA's fourth attempt to listen for signals showing that the Mars Lander did not perish during the frigid -- and long -- Martian winter.
The Mars Odyssey made similar attempts in January, February and April of this year.
"To be thorough, we decided to conduct this final session around the time of the summer solstice, during the best thermal and power conditions for Phoenix," said Chad Edwards, chief telecommunications engineer for NASA's Mars Exploration Program, in a statement.
While the Mars Lander was not designed to survive the extreme cold of a long Martian winter, scientists have held out a slim hope that its solar cells would contain enough power to transmit a signal when spring arrives on the planet's surface.
The Phoenix Mars Lander, which worked two months beyond its expected three-month mission, gathered information on the content of Martian soil near the planet's north pole in 2008. The lander dug up and analyzed Martian soil samples , discovered frozen water just below the surface and verified that snow falls on Mars .
The Mars Lander first began to slow as the Martian winter approached in late 2008.
Since the Lander is powered by solar cells and the Mars nights began growing longer at the end of October, 2008, scientists began to remotely power down as many parts of the Lander as possible to minimize its energy needs. The aim: to keep a few instruments to keep running as long as possible to provide a better chance at re-starting the craft this year.
NASA scientists received the last transmission from the Lander on Nov. 2, 2008.
Scientists noted at the time that once the Mars Lander dies, it was doubtful it could be revived after spending months in the dark and frigid cold. The Martian year, which is equivalent to about 687 Earth days, has a longer winter season, when the temperatures can drop to minus 191 degrees Fahrenheit.