Mars Odyssey's Gamma-ray spectrometer (GRS) instrument has detected large amounts of Hydrogen on Mars, particularly near the south pole. This is an indication that water ice exists in the upper meter of these areas of the Martian surface. The epithermal neutron data ranges from 0 to about 12 counts per second. The blue areas indicate high concentrations of Hydrogen (low epithermal neutron counts).
A series of animations was generated to support a Space Science Update (SSU) on the topic. These animations were match-rendered with unsmoothed, smoothed, and Viking true-color data.