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 LCROSS - Lunar CRater Observation and Sensing Spacecraft
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Lunar CRater Observation and Sensing Satellite (LCROSS)

Crater Impact Characteristics
The primary goal of LCROSS was to measure the concentration of water ice (ice to dust ratio) in permanently shadowed lunar regolith. Setting constraints on water ice set a fiducial for the LRO studies of hydrogen neutrons, that were expected to have water ice as a source. Several important processes occur when a body strikes the lunar surface, including the initial impact, ejecta and plume dispersion, and the exposure of fresh subsurface (Figure 1). Continuously monitoring the impact events at a variety of spatial (m to km to exosphere scales) and temporal scales (sec to minutes to days) allowed us to understand lunar impact processes and assess the likelihood that water ice, due to impacts occurring within the permanently shadowed target crater, may be distributed non-uniformly.

Life cycle of a lunar impacr showing development over 1 hour
Figure 1 The life cycle of a lunar impact and associated time and special scales. The LCROSS measurement methods are “layered” in response to the rapidly evolving impact environment.

Plime Expectations

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The upper stage of the launch vehicle (about the weight of a large SUV) impacted into the South Pole of the Moon at over 9,000 km/h (5,600 mph).
SUV and the Moon

The impact excavated a crater about 1/3 of a football field wide and about the depth of the deep end of a swimming pool.
Football field and the Moon

The amount of material (dust and probably ice) ejected could fill ten school buses, or ten Space Shuttle cargo bays. The plume was expected to reach nearly 50 km high (over 30 miles)!
10 Space shuttles

centaur impact site

IR still of Centaur Crater

Watch an animation of a meteoroid hitting the Moon’s surface.
Visit the NASA Mission Site @ http://www.nasa.gov/lcross

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Editor: Brian Day
NASA Official: Daniel Andrews
Last Updated: October 2010