And in a prelude to winter and the demise of NASA’s Phoenix Mars lander, snow has been spotted falling from the clouds above. As the Martian days shorten and temperatures drop, Phoenix’s solar panels will eventually not be able to produce enough energy to keep the spacecraft warm.
NASA, however, has given a second extension to the mission, originally intended to last just three months and now in its fifth month. The extension will allow scientists to gather data until Phoenix’s final day, anticipated to arrive in mid- to late-November or perhaps early December.
“We are trying to literally make hay as the sun shines,” said Barry Goldstein, Phoenix’s project manager during a news conference on Monday, “and really try to get the most of the science instruments in these last few days before the end of the mission.”
The Phoenix landed north of the Martian Arctic circle on May 25, during late spring for Mars’ northern hemisphere. Its mission was to explore whether that environment, currently dry, cold and presumably lifeless, might have been habitable in the past when Mars’ axis was tipped farther over and pointed toward the Sun half of the time.
The mission has produced a trove of data for scientists to sift and ponder, but no blockbuster discoveries.
Instruments analyzing samples of dirt dug up by the Phoenix have now identified signs of clays and calcium carbonate, materials that on Earth form only in the presence of liquid water.
That liquid water is not there currently. A layer of water ice exists a few inches below surface, and the layer of soil on top of the ice is “very, very dry,” said Michael Hecht of NASA’s Jet Propulsion Laboratory.
Earlier, scientists had announced the presence of perchlorates, a class of chemicals that are toxic in high concentrations, although the implications for the possibility of life are unclear. The perchlorates could also explain the dryness of the soil, soaking up any moisture.
No organic molecules have yet been identified. “If there is any there, it’s not very much,” said William V. Boynton of the University of Arizona, lead scientist of the instrument known as the thermal and evolved gas analyzer.
The weather station, by shining a laser beam straight up and looking at the reflections, has spotted crystals of water ice — snow — from clouds 2.5 miles above the surface, although the snow has so far not reached the ground.
As the season moves to winter, the Phoenix will eventually be encased in a tomb of carbon dioxide ice. Mission managers said that after the spacecraft thaws out when spring returns, they will attempt to invoke its “Lazarus mode,” but they doubted the spacecraft would revive.
Mr. Goldstein said the extreme cold would make electronic components brittle and prone to shattering. “The vehicle will probably not survive that,” he said.