Evidence for Water Ice Near Mercury's North Pole from MESSENGER Neutron Spectrometer Measurements

Measurements by the Neutron Spectrometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show decreases in the flux of epithermal and fast neutrons from Mercury's north polar region that are consistent with the presence of water ice in permanently sha...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2013-01, Vol.339 (6117), p.292-296
Main Authors: Lawrence, David J., Feldman, William C., Goldsten, John O., Maurice, Sylvestre, Peplowski, Patrick N., Anderson, Brian J., Bazell, David, McNutt, Ralph L., Nittler, Larry R., Prettyman, Thomas H., Rodgers, Douglas J., Solomon, Sean C., Weider, Shoshana Z.
Format: Article
Language:English
Subjects:
Backscattering
Deposition
Environmental conditions
Fast neutrons
Hydrogen
Italian ices
Latitude
Mercury (planet)
Mercury surface
MESSENGER Mission
Neutrons
North Pole
Onboard
Online
Planets
Polar regions
Radar
Radio astronomy
Scientific Concepts
Signals
Simulations
Spacecraft
Spectrum analysis
Water
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Summary:Measurements by the Neutron Spectrometer on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft show decreases in the flux of epithermal and fast neutrons from Mercury's north polar region that are consistent with the presence of water ice in permanently shadowed regions. The neutron data indicate that Mercury's radar-bright polar deposits contain, on average, a hydrogen-rich layer more than tens of centimeters thick beneath a surficial layer 10 to 30 cm thick that is less rich in hydrogen. Combined neutron and radar data are best matched if the buried layer consists of nearly pure water ice. The upper layer contains less than 25 weight % water-equivalent hydrogen. The total mass of water at Mercury's poles is inferred to be 2 × 10 16 to 10 18 grams and is consistent with delivery by comets or volatile-rich asteroids.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1229953