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How did LCROSS confirm water ice near the Moonâs south pole?
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Moon
(Left) Near side of Earth's Moon, photographed by the Galileo spacecraft on its way to Jupiter. (Right) Far side of the Moon with some of the near side visible (upper right), photographed by the Apollo 16 spacecraft.
The LCROSS mission confirmed the presence of water ice near the Moonâs south pole by deliberately crashing its Centaur upper stage into the floor of the Cabeus crater on October 9, 2009.12
Because the floor of this crater remains permanently in shadow, scientists hypothesized that water could survive there as ice beneath the surface. Upon impact, the Centaur stage struck the lunar surface at a speed of 9,000 km (5,600 miles) per hour, creating a plume of debris. The LCROSS spacecraft, which was trailing the impactor, flew through this plume to analyze its composition. Subsequent analysis of the material ejected by the impact revealed that the lunar soil at the bottom of the crater contained 5.6 percent water ice.123