Snow discovered on Mars!

HOUSTON, Texas - September 30, 2008 - In an unprecedented discovery, NASA's Phoenix Mars Lander has found snow falling from clouds on Mars, scientists said Tuesday.

A laser instrument collecting data on how the atmosphere and surface interact on Mars detected snow from clouds about four kilometers (2.5 miles) above the spacecraft's landing site. The data found the snow vaporized before reaching the ground.

"Nothing like this view has ever been seen on Mars," said Jim Whiteway, of York University, Toronto, lead scientist for the Canadian-supplied Meteorological Station on Phoenix. "We'll be looking for signs that the snow may even reach the ground."

Spacecraft soil experiments also have provided dramatic evidence of past interaction between minerals and liquid water, processes that occur on Earth. Phoenix touched down in the Martian arctic on May 25.

Phoenix data also suggested the presence of calcium carbonate, the main composition of chalk, and particles that could be clay. Most carbonates and clays on Earth form only with water on hand.

"We have found carbonate," said William Boynton of the University of Arizona, lead scientist for the Thermal and Evolved Gas Analyzer (TEGA). "This points toward episodes of interaction with water in the past."

"We are still collecting data and have lots of analysis ahead, but we are making good progress on the big questions we set out for ourselves," said Phoenix Principal Investigator Peter Smith of the University of Arizona, Tucson.

The Phoenix Lander started digging trenches into Martian soil after touching down near the planet's north pole on May 25, revealing a white substance that scientists said was ice in June.

Now scientists want to examine whether that ice ever thaws to assess whether the environment has been favorable for life, a key aim of the mission.