Vertical distribution of hydrogen at high northern latitudes on Mars: The Mars Odyssey Neutron Spectrometer

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Read Full Article (file size: 305643 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L05201, doi:10.1029/2006GL028936, 2007 Vertical distribution of hydrogen at high northern latitudes on Mars: The Mars Odyssey Neutron Spectrometer W. C. Feldman Los Alamos National Laboratory, Los Alamos, New Mexico, USA M. T. Mellon Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA O. Gasnault Centre d'Etude Spatiale des Rayonnements, Observatoire Midi-Pyrenees, Toulouse, France B. Diez Centre d'Etude Spatiale des Rayonnements, Observatoire Midi-Pyrenees, Toulouse, France R. C. Elphic Los Alamos National Laboratory, Los Alamos, New Mexico, USA J. J. Hagerty Los Alamos National Laboratory, Los Alamos, New Mexico, USA D. J. Lawrence Los Alamos National Laboratory, Los Alamos, New Mexico, USA S. Maurice Centre d'Etude Spatiale des Rayonnements, Observatoire Midi-Pyrenees, Toulouse, France T. H. Prettyman Los Alamos National Laboratory, Los Alamos, New Mexico, USA Abstract Neutron leakage currents measured using the Mars Odyssey Neutron Spectrometer are used to develop a two-layer model of the distribution of hydrogen (here parameterized as water-equivalent hydrogen, WEH) at high northern latitudes. The WEH abundance in the upper layer, Wup, was found to range between 1% and about 5%. The maximum value of the apparent thickness, D, of this upper layer peaks at about 60° latitude, giving the appearance of zonal bands of enhanced D in both hemispheres. This maximum is consistent with an expected transition from WEH contained solely in hydrous minerals at lower latitudes, to WEH contained both in the forms of water ice and water of hydration at high latitudes. A strong anti-correlation between the WEH concentration in the lower layer and apparent depth, D, at high latitudes is observed and may provide clues to the origin of these deposits. Received 28 November 2006; accepted 25 January 2007; published 3 March 2007. Keywords: Mars; water; Vastitas Borealis Formation. Index Terms: 0702 Cryosphere: Permafrost (0475); 0738 Cryosphere: Ice (1863); 5462 Planetary Sciences: Solid Surface Planets: Polar regions; 6225 Planetary Sciences: Solar System Objects: Mars. Read Full Article (file size: 305643 bytes) Cited by Citation: Feldman, W. C., M. T. Mellon, O. Gasnault, B. Diez, R. C. Elphic, J. J. Hagerty, D. J. Lawrence, S. Maurice, and T. H. Prettyman (2007), Vertical distribution of hydrogen at high northern latitudes on Mars: The Mars Odyssey Neutron Spectrometer, Geophys. Res. Lett., 34, L05201, doi:10.1029/2006GL028936. Copyright 2007 by the American Geophysical Union.

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