Spirit finds more signs of water on Mars

The US rover Spirit has found more signs that water once existed on Mars, days after its twin probe discovered signs that parts of the Red Planet were once drenched with water and could possibly have supported life, NASA said.
The latest findings point to smaller amounts of water, after Spirit scraped a tiny hole in a volcanic rock and found shiny material resembling minerals that crystallise after water evaporates.
"If we found this rock on Earth, we would say it is a volcanic rock that had a little fluid moving through it," scientist Ray Arvidson said in a statement Friday.
The water, with minerals dissolved in it, may have flowed with the lava that created the rock, or may have somehow entered the rock later.
The shiny substances were inside a volcanic rock dubbed "Humphrey," after Spirit drilled a two-millimeter (0.08-inch) hole.
NASA now plans to have Spirit drill a deeper hole in another rock to confirm that the bright material is not dust that entered the rock's cracks and pores over the centuries.
The discovery indicates a far smaller amount of water than what Opportunity, Spirit's twin, discovered signs of halfway around the planet.
The US space agency announced Tuesday that Opportunity had found proof that parts of the planet had once been drenched with water, and that the region would have been "a good habitable environment for some period of time." Scientists said they still had no proof that life existed on the planet.
NASA based its findings on exposed bedrock in a small crater close to Opportunity's landing site in the Meridiani Planum. The robot has spent much of the past three weeks on a study of a single rock NASA scientists dubbed "El Capitan."
Data taken by an X-ray spectrometer aboard the robot and relayed to Earth showed a high concentration of sulfur, which is likely to have precipitated out of a solution at the bottom of a salty lake or sea.
The two robot probes blasted off from Earth in mid-2003 and have been exploring the Martian surface since January. Combined, they have spent more than 100 days on Mars. Spirit and Opportunity are expected to keep looking for signs of life at least until April.