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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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