The LCROSS Cratering Experiment

<jats:title>Watering the Moon</jats:title> <jats:p> About a year ago, a spent upper stage of an Atlas rocket was deliberately crashed into a crater at the south pole of the Moon, ejecting a plume of debris, dust, and vapor. The goal of this event, the Lunar Crater Observation and Sensing Satellite (LCROSS) experiment, was to search for water and other volatiles in the soil of one of the coldest places on the Moon: the permanently shadowed region within the Cabeus crater. Using ultraviolet, visible, and near-infrared spectroscopy data from accompanying craft, <jats:bold> Colaprete <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="463" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1186986">463</jats:related-article> ; see the news story by <jats:bold> <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6003" page="434" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.2010.330.6003.330_434">Kerr</jats:related-article> </jats:bold> ; see the cover) found evidence for the presence of water and other volatiles within the ejecta cloud. <jats:bold> Schultz <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="468" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1187454">468</jats:related-article> ) monitored the different stages of the impact and the resulting plume. <jats:bold> Gladstone <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="472" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1186474">472</jats:related-article> ), using an ultraviolet spectrograph onboard the Lunar Reconnaissance Orbiter (LRO), detected H <jats:sub>2</jats:sub> , CO, Ca, Hg, and Mg in the impact plume, and <jats:bold> Hayne <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="477" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1197135">477</jats:related-article> ) measured the thermal signature of the impact and discovered that it had heated a 30 to 200 square-meter region from ∼40 kelvin to at least 950 kelvin. <jats:bold> Paige <jats:italic>et al.</jats:italic> </jats:bold> (p. 479) mapped cryogenic zones predictive of volatile entrapment, and <jats:bold> Mitrofanov <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="483" related-article-type="in-this-issue" vol="330" xlink:href="10.1126/science.1185696">483</jats:related-article> ) used LRO instruments to confirm that surface temperatures in the south polar region persist even in sunlight. In all, about 155 kilograms of water vapor was emitted during the impact; meanwhile, the LRO continues to orbit the Moon, sending back a stream of data to help us understand the evolution of its complex surface structures. </jats:p>