A significant layer of water ice has been spotted across the mid latitudes of Mars, located just a few feet below the planet’s surface. This new finding adds a new layer to the geological history of the Red Planet, and also may offer a useful source of water for future human expeditions sent there.

Mars has been found to hold water ice in previous explorations, such as in the case of NASA’s Phoenix lander finding subsurface ice at Mars’ north pole, and the discovery of a Lake Superior-sized reservoir of subsurface ice by the Mars Reconnaissance Orbiter (MRO) in 2016. This new discovery was announced by U.S. Geological Survey geologist Colin Dundas, highlighting the spectral analysis of eight sites imaged by MRO with steep slopes that exposed the subsurface rock layers. Amongst those layers were bands that showed the spectral signature for water, just three to six feet below the surface.

"[They are] very cool images that capture the subsurface ice predicted by theory," says Caltech planetary scientist Bethany Ehlmann. "Also, we may be able to core the ice for a record of climate change on recent Mars, much like we do on Earth." Dundas theorizes that the ice formed during heavy snowfalls that occurred millions of years ago, possibly when Mars had a greater tilt to its axis, making its seasons more pronounced.

"It’s looking more encouraging that water ice could be available at depths shallow enough that could be used as resources for human missions to Mars," says director of the Center for Space Resources at the Colorado School of Mines, Angel Abbud-Madrid. This easily accessible source of water just below the Martian surface can be used for not just drinking water, but also as a hydrogen fuel and breathable oxygen source.