NASA’s LCROSS mission confirmed water ice near the Moon’s south pole by impacting the lunar surface in 2009.
LCROSS, the Lunar Crater Observation and Sensing Satellite, launched with the Lunar Reconnaissance Orbiter on June 18, 2009. Its spent Centaur rocket stage struck the permanently shadowed Cabeus crater on October 9, 2009. LCROSS followed behind, flew through the debris plume, and observed it before also impacting the Moon.
Spectroscopic measurements of the plume provided evidence for water in the crater’s cold, permanently shadowed region. These areas receive little or no sunlight, allowing volatile substances such as water ice to remain frozen for long periods.
The mission’s result did not mean the Moon has Earth-like lakes or oceans. Instead, it showed that water ice is mixed into lunar soil in extremely cold polar environments. The Lunar Reconnaissance Orbiter, launched on the same rocket, was a separate spacecraft with a broader mapping mission.