Water on Mars: Scientific Results from the Mars Odyssey Neutron Spectrometer

The Mars Odyssey Neutron Spectrometer (MONS) is described and its capabilities to detect and quantify deposits of H within about one meter of the surface will be presented. After two Martian Years in mapping orbit about Mars, three distinct domains of hydrogen deposits have been delimited. High latitude domains in both hemispheres contain large, generally buried deposits of hydrogen and a near-equatorial domain contains more modest, yet significant deposits. All observations are specified in units of water-equivalent hydrogen and are compared with other observations of near-surface deposits of H2O and OH. They are also discussed in terms of theories of volatile exchange between different water reservoirs through the atmosphere or through a system of aquifers.