Artist concept of the Phoenix lander,
sleeping under the darkening polar skies of Martian autumn.It seems like only last month that we witnessed the drama of NASA's Phoenix landing on Mars. We were on the edge of our seats in Chabot's planetarium during those "seven minutes of terror" as Phoenix burned a meteoric path through Mars' atmosphere.
But that was last May, and Phoenix has operated near Mars' northern polar ice cap going on six months now! The mission has continued a couple months longer than originally planned, giving Phoenix more time to dig in the icy soil, bake scooped up samples to detect what chemicals sublimate, track the polar weather day and night, and look to the skies with its various instruments.
Phoenix sent back some very interesting news. Indeed, it had landed on what turned out to be dust-coated water ice; ice that contains chemicals like calcite and perchlorate-- the former of which may indicate past liquid water on Mars, the latter of which, however, is generally toxic, and may complicate arguments for life, past or present, on Mars.
One of the more "fanciful" detections by Phoenix was falling snow: two or three miles above, Phoenix detected ice crystals falling from clouds-- albeit flakes that never made it to the ground, instead evaporating like Earthly virga back into the atmosphere.
But Phoenix’s mission has a built-in conclusion (unlike the seemingly perpetual Energizer Bunnies exploring the Martian tropics, aka the Mars Exploration Rovers). Phoenix landed at 68 degrees north latitude-- that’s equivalent on Earth to the north coast of Alaska, Norway, or south central Greenland-- prior to Martian northern summer solstice (which was June 25). As with Earthly summertime, the polar days were unending, the Sun above the horizon 24 hours a day (yes, Mars' day is about 24 hours long, just as on Earth). This provided Phoenix with its electrical power, generated by photovoltaic panels.