Detection of water in the LCROSS ejecta plume.
Several remote observations have indicated that water ice may be presented in permanently shadowed craters of the Moon. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed to provide direct evidence. On 9 October 2009, a spent Centaur rocket struck the persistently shadowed region within the lunar south pole crater Cabeus, ejecting debris, dust, and vapor. This material was observed by a second "shepherding" spacecraft, which carried nine instruments, including cameras, spectrometers, and a radiometer. Near-infrared absorbance attributed to water vapor and ice and ultraviolet emissions attributable to hydroxyl radicals support the presence of water in the debris. The maximum total water vapor and water ice within the instrument field of view was 155 ± 12 kilograms. Given the estimated total excavated mass of regolith that reached sunlight, and hence was observable, the concentration of water ice in the regolith at the LCROSS impact site is estimated to be 5.6 ± 2.9% by mass. In addition to water, spectral bands of a number of other volatile compounds were observed, including light hydrocarbons, sulfur-bearing species, and carbon dioxide.
NASA Ames Research Center, Moffett Field, CA 94035, USA. Anthony.Colaprete-1@nasa.gov
Anthony
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Colaprete
Peter
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Schultz
Jennifer
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Heldmann
Diane
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Wooden
Mark
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Shirley
Kimberly
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Ennico
Brendan
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Hermalyn
William
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Marshall
Antonio
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Ricco
Richard C
RC
Elphic
David
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Goldstein
Dustin
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Summy
Gwendolyn D
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Bart
Erik
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Asphaug
Don
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Korycansky
David
D
Landis
Luke
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Sollitt
D005118:Extraterrestrial Environment; D007053:Ice; D016081:Moon; D019265:Spectroscopy, Near-Infrared; D014867:Water
D007053:Ice; D014867:Water