New Evidence: Past Water on Mars

The NASA rover Spirit, currently prowling Mars' Gusev Crater, has found a patch of sand that strongly indicates water was present at the site. The soil is 90 percent pure silica. Project scientist Steve Ruff of ASU explained that, on Earth, "the only way you can achieve that level of enrichment is by pumping water through rocks." Steve Squyres of Cornell University added, "It was astonishing."