Posted: Tue, Jun 8, 2004, 6:31 PM ET (2231 GMT)
NASA's Mars Exploration Rover Spirit has discovered additional evidence that liquid water once existed on Mars, scientists said Tuesday. A spectrometer on Spirit discovered high concentrations of magnesium and sulfur in a trench dug into Martian soil by the rover. The levels of both elements varied in lockstep in different locations of the trench, suggesting that the elements are combined into a magnesium sulfate salt. Such a salt, according to scientists, would most likely be created by groundwater dissolved minerals as it percolated through rocks below the surface, leaving behind the resulting mineral salts when the water evaporated near the surface. This source of water is different from what scientists found on the opposite side of the planet with the Opportunity rover, where bedrock outcrops showed evidence of water flowing on the surface. Spirit dug the crater during its journey to the Columbia Hills, over three kilometers from its landing site.

Related Links:

•  AP article
•  Press Association article
•  NASA/JPL press release