The Global Distribution of Near-Surface Hydrogen on Mars

Bill Feldman

Neutron data observed using the Neutron Spectrometer aboard 2001 Mars Odyssey provide a lower limit to the global inventory of Martian water-equivalent hydrogen. Hydrogen-rich deposits ranging between 20% and 100% water-equivalent by mass are found poleward of +/-50^o latitude and less rich, but significant deposits are found at near-equatorial latitudes. The equatorial deposits range between 2% and 10% water-equivalent hydrogen by mass and reach their maximum in two regions that straddle the zero-km elevation contour. The hydrogen content of surface soils in the latitude range between +/-(50^o to 80^o) as seen from orbit are equal to within determination uncertainties. A lower-limit estimate of the global inventory of near surface hydrogen amounts to a global water layer about 14 cm thick if the reservoir sampled from orbit is assumed to be 1 m thick.