Detection of Water in the LCROSS Ejecta Plume

• Published in: Science (American Association for the Advancement of Science) Vol. 330; no. 6003; pp. 463 - 468
• Main Authors: Colaprete, Anthony, Schultz, Peter, Heldmann, Jennifer, Wooden, Diane, Shirley, Mark, Ennico, Kimberly, Hermalyn, Brendan, Marshall, William, Ricco, Antonio, Elphic, Richard C, Goldstein, David, Summy, Dustin, Bart, Gwendolyn D, Asphaug, Erik, Korycansky, Don, Landis, David, Sollitt, Luke
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 22.10.2010; The American Association for the Advancement of Science
• Subjects: Astronomy; Average linear density; Craters; Debris; Earth, ocean, space; Ejecta; Exact sciences and technology; Extraterrestrial Environment; Features, landmarks, mineralogy, petrology, and atmosphere; Hydroxyl radicals; Ice; Impact craters; Italian ices; Lunar craters; Moon; Planetology; Radiance; Regolith; RESEARCH ARTICLE; Solar system; Spacecraft; Spectral bands; Spectral reflectance; Spectrometers; Spectroscopy, Near-Infrared; Sunlight; Water; Water vapor; Wavelengths; Absorbance; Moon; Steam; Hydroxyl radicals; Lunar crater; Ice; Regolith
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1186986

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 (1). 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.