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.
Colaprete
Anthony
A
NASA Ames Research Center, Moffett Field, CA 94035, USA. Anthony.Colaprete-1@nasa.gov
Schultz
Peter
P
Heldmann
Jennifer
J
Wooden
Diane
D
Shirley
Mark
M
Ennico
Kimberly
K
Hermalyn
Brendan
B
Marshall
William
W
Ricco
Antonio
A
Elphic
Richard C
RC
Goldstein
David
D
Summy
Dustin
D
Bart
Gwendolyn D
GD
Asphaug
Erik
E
Korycansky
Don
D
Landis
David
D
Sollitt
Luke
L
D005118:Extraterrestrial Environment; D007053:Ice; D016081:Moon; D019265:Spectroscopy, Near-Infrared; D014867:Water
D007053:Ice; D014867:Water