NASA's Mars Phoenix Lander, which spent the summer in Mars' northern polar regions performing a variety of science experiments, caused quite a stir when rumors circulated that it had discovered signs of life on the Red Planet

Science/AAAS

NASA eventually held a press conference to dispel the rumors, promising that more details would eventually be revealed when scientists got around to publishing papers that would describe the experiments in detail. That day has finally arrived; today's issue of Science contains four papers that describe various findings from the mission. There's no sign of alien life, but the studies do reveal an active water cycle on Mars—including night-time snowfall.

The papers rely on evidence from a variety of the instruments on the lander, and the description of the data provides an impressive catalog of the various ways that Phoenix could prod and query the Martian pole. In the months before Martian winter shut the lander down, it managed to dig a dozen trenches, taking soil samples from each. These samples went into wet and dry chemistry labs, had their conductivity tested, and were even examined using an atomic force microscope. Meanwhile, cameras and a LIDAR system (a laser-based range detector) scanned the surroundings.

The overall conclusion is that the northern pole has an active water cycle. This had been suggested by a variety of evidence from orbital sensors, as well early images returned from Phoenix. It's also not a huge shock, given the seasonal growth and retreat of the polar ice cap. Still, Phoenix provided some significant details on the cycling of water in the area where it landed.  [ARS Technica...]  [Comments... ]