Lunar water likely comes from solar wind
Scientists from the university of Michigan have concluded that a likely source of the water deposits found in lunar soil comes from the Sun's solar winds.
For many years, it was believed that the moon was about as dry as things get, but over the past five years, that notion has come to change. New research has been done on the soil samples brought back from the Apollo missions in the 60's and 70's, as well as on the moon itself via spacecraft observations; as it turns out, the moon is quite wet.
The moon hardly needs a caption, but it gets one anyway
There is a surprisingly large concentration of ice crystals in the moon, as well as in the dust- and rock-layer called regolith, which coats the moon's surface. One standing theory is that all of this water is a result of impacts with comets and other rocks rich in water. Another theory, first thought of in the late 1970's states that the Sun may be responsible, and a recent paper published in Nature Geoscience supports this theory.
University of Michigan's Youxue Zhang and colleagues at the University of Tennessee, and California Institute of Technology, believe that the solar winds which are emitted by the Sun have been creating the water through chemical reactions. The solar wind, which hammers the solar system endlessly and is responsible for the auroras seen on planetary poles, is rich in hydrogen ions. These ions could be combining with oxygen molecules on the moon's surface, and thus create H2O, water.
The researchers have been using infrared and mass spectrometry top analyze lunar samples from Apollo, and have found hydroxyl inside aglutinate glass (aglutinate is common and makes up 50% of the lunar regolith). The hydroxyl, essentially a bonded hydrogen and oxygen atom, would need another hydrogen atom to become water, but it is a first step in the process. The research shows that the creation of hydroxyl likely comes from interaction between the moon and solar wind.
Grain of the glass which hold hydroxyl groups on the moon
This in turn makes it likely that the water ice found in the north and south poles of the moon also exist as a result of the solar wind. That would make it likely that other inhospitable places in the solar system, such as the planet Mercury or asteroid Eros, may hold water as well; a very important finding if our species ever plans on establishing permanent colonies off-world.