Water on the Moon – The NASA LCROSS Mission

Chick Woodward
Professor, Department of Astronomy
University of Minnesota

If water at the poles of the Moon can be accessed by humans, then water can be used for life support resources at future lunar bases; specifically, water can be broken down into oxygen for humans and hydrogen for fuel.  The early evidence for water existing at the lunar poles in permanently shadowed craters included the detection of excess H atoms by the Lunar Prospector neutron spectrometer and anomalous bistatic radar returns from the Clementine lunar orbiter.  However, this evidence for water is indirect and the ice content subject to controversy.  Direct sampling by drilling is a future concept to unequivocally determine regolith water content; however, such experiments currently are not on any NASA Lunar mission manifest. As a prelude to in situ searches, assessment of the polar regolith water content using remote sensing techniques was executed by the NASA Lunar Crater Observations and Sensing Satellite (LCROSS) Mission  impacting a permanently shadowed crater near the south pole of the Moon (Cabeus) at 11:31 UTC on 2009 October 09.  LCROSS piggy-backed on the launch of the Lunar Reconnaissance Orbiter and used the spent second stage as an impactor. The mission objective of LCROSS was to impact and excavate permanently shadowed lunar regolith, ejecting this material above the crater rim into sunlight where measurements of water ice and water vapor entrained in the ejecta curtain using remote sensing methods from both the shepherding spacecraft and from ground-based observatories would enable extraction of the regolith water content. I will highlight some of the LCROSS mission objectives and provide a status report of current findings.