Face the cold, hard fact: there's ice hiding on Mars
Jean-Louis Santini in Washington June 22, 2008

THE Phoenix Mars Lander has confirmed scientists' long-held belief that ice is hiding under the surface in the red planet's north.

The lander's robotic arm began digging trenches after touching down near the planet's north pole on May 25, revealing a white substance that scientists had said could be either salt or ice. Phoenix flexed its arm again to enlarge a trench on June 15. It then took pictures of eight bright bits of material the size of dice inside the hole, which scientists dubbed "Dodo-Goldilocks".

Photographs taken four days later show the material had vanished, settling the debate about whether it was salt or ice. Scientists at the Jet Propulsion Laboratory in Pasadena, California, concluded that the material was frozen water that evaporated in the sun. Salt would not have reacted that way, they said. "We found what we were looking for," Phoenix science team member Mark Lemmon said. "We came to this site because we were expected to find water ice."

Scientists believed that a vast sheet of ice was hiding in the planet's north pole after NASA's Mars Odyssey surveyed it in 2002. "We have found the proof that we have been seeking that showed that this bright material really is water ice, and not another substance," said Phoenix principal investigator Peter Smith, of the University of Arizona, Tucson.

"Now we know for sure that we are on an icy surface and we can really meet the science goal of our mission at the highest level." Besides evidence of water, the three-month Phoenix mission is also hoping to find life-supporting organic minerals in the polar region. The probe has instruments that can melt any ice collected.

Water filtered down on Mars may have left its mark on surrounding minerals, and impurities in the ice could tell a great deal about the climatic history of this region of the planet.

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