Finding Mars on Earth: Chilean Hot Springs Provide New Clues to a Martian Mystery

In 2007, the Mars Exploration Rover (MER) Spirit came across a slightly raised platform, roughly pentagonal in shape and 90 meters across, which scientists named Home Plate. The rocky outcrop had a base of solidified ash, with nearby deposits of gas-filled basalts. Next to the plateau, nubby, nodular chunks of rock showed up, and light-colored soil just beneath the surface was exposed by the rover’s wheels. Mineralogical spectra of the bright soil were beamed back to Earth, revealing, to the scientists’ surprise, that it was composed almost entirely of silica.