On Mars, water ice may be both biological buried treasure and a rich resource for future Mars explorers. NASA’s 2001 Mars Odyssey spacecraft has found enormous quantities of subsurface water ice. Scientists using the spacecraft’s gamma ray spectrometer instrument have detected hydrogen in the upper three feet (one-meter) of soil. That hydrogen is believed likely to be in the form of water ice. The spacecraft spotted enough Mars water ice to fill Lake Michigan twice over in what may be a “splash” of data, with the deluge yet to come.