Tue, September 30, 2008
Sci-Tech > Science

U.S. Mars lander Phoenix sees falling snow

2008-09-30 00:48:07 GMT2008-09-30 08:48:07 (Beijing Time) Xinhua English

This photo released by NASA shows the edge of a solar panel on NASA's Phoenix Mars Lander, right, in a trench on the surface of Mars, where a sample of soil was taken by the lander. NASA announced Monday, Sept. 29, 2008, that the spacecraft discovered two minerals in the Martian soil that suggest interaction with water in the past.(AP Photo/NASA, JPL-Caltech)

WASHINGTON, Sept. 29 (Xinhua) -- U.S. Phoenix Mars Lander has detected snow falling from Martian clouds, the U.S. space agency NASA announced on Monday.

A laser instrument designed to gather knowledge of how the atmosphere and surface interact on Mars, detected snow from clouds about 4 kilometers above the spacecraft's landing site. Data show the snow vaporizing 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."

In the meantime, spacecraft soil tests experiments also have provided evidence of past interaction between minerals and liquid water, processes that occur on Earth.

Phoenix experiments also yielded clues pointing to calcium carbonate, the main composition of chalk, and particles that could be clay. Most carbonates and clays on Earth form only in the presence of liquid water.

"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.

Since landing on May 25, Phoenix already has confirmed that a hard subsurface layer at its far-northern site contains water-ice.

Determining whether that ice ever thaws would help answer whether the environment there has been favorable for life, a key aim of the mission.

The Phoenix mission, originally planned for three months on Mars, now is in its fifth month. However, it faces a decline in solar energy that is expected to curtail and then end the lander's activities before the end of the year.

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