NASA's Phoenix Mars Lander, having already uncovered water ice in the soil of the Red Planet's northern polar plains, has now spotted another sight familiar to those of us who dwell in the higher latitude climes back on Earth: falling snow.
Using lidar (analogous to radar, with pulses of laser light standing in for radio waves), Phoenix picked up signs of snow drifting down from clouds some 2.5 miles (four kilometers) overhead. It has not been seen reaching the Martian surface; it appears to vaporize before landfall.
"Nothing like this view has ever been seen on Mars," James Whiteway of York University in Toronto said in a statement. Whiteway is lead scientist for Phoenix's Meteorological Station (MET), the Canadian Space Agency's contribution to the mission. He added that the MET team will now seek to discover "signs that the snow may even reach the ground."
Those signs, and any other clues NASA hopes to turn up with the lander, had better appear soon. Phoenix, which touched down on May 25, has already gone well beyond the original three-month scope of its mission and will soon lose favor with the sun, which, via solar arrays, charges batteries that power Phoenix's activities and warm its components.
"For nearly three months after landing, the sun never went below the horizon at our landing site," Barry Goldstein, project manager for the lander at NASA's Jet Propulsion Laboratory, said in a statement. "Now it is gone for more than four hours each night, and the output from our solar panels is dropping each week." With Martian winter rapidly approaching, NASA expects that Phoenix will grind to a frigid halt, never to reawaken, before the end of the year.