The most likely source of the water locked inside soils on
the moon's surface is the constant stream of charged particles from the sun
known as the solar wind, a University of Michigan researcher and his colleagues
have concluded.
Over the last five years, spacecraft observations and new
lab measurements of Apollo lunar samples have overturned the long-held belief
that the moon is bone-dry.
In 2009, NASA's Lunar Crater Observation and Sensing
satellite, known as LCROSS, slammed into a permanently shadowed lunar crater
and ejected a plume of material that was surprisingly rich in water ice. Water
and related compounds have also been detected in the lunar regolith, the layer
of fine powder and rock fragments that coats the lunar surface.