A new global map of Mars shows likely locations of water ice based on observations of hydrogen made by NASA’s Odyssey spacecraft. The presence of hydrogen is a strong indicator that water — most of it almost surely frozen — exists near the surface of Mars, embedded in the soil. Liquid water might exist on the red planet, but no data so far has provided firm indications. The new map is based on more than a year’s worth of Odyssey data, much of which has already been announced. The purpose is to show the extent of frozen water on Mars in a visual format. Bill Feldman, a Los Alamos National Laboratory researcher who led the observations, called the map “breathtaking.”