Water on the moon? Maybe a lot more than we thought ... thanks to the sun.
A new study finds 'an unanticipated, abundant reservoir' of water on the moon, molecules formed on the surfaces of oxygen-bearing rocks bombarded by protons from the solar wind.
The moon's top layer of crushed rock and soil may hold far more water than previously estimated, according to a new study.Skip to next paragraph
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Most of that water can trace its origin to protons streaming from the sun, the researchers show, confirming in samples of lunar soil a mechanism for making lunar water that until now largely had been the province of theoretical models.
The find "represents an unanticipated, abundant reservoir" of water on the moon, according to researchers from three US universities, who formally reported their results Sunday in the journal Nature Geoscience. And it could help explain the presence of water on other airless planets and asteroids in the inner solar system.
"Reservoir" does not mean a source of readily tapped liquid, the researchers caution. The evidence shows up as hydroxyl – a single oxygen and hydrogen atom representing two-thirds of a standard water molecule. Hydroxyl and water molecules are captured in tiny deposits of glass in rock and soil grains. The glass forms from heat generated when micrometeoroids slam into the surface and fuse soil grains into tiny clumps.
Still, the mini-clumps containing the glass may represent between 50 and 70 percent of the material making up lunar soils, says Lawrence Taylor, a University of Tennessee geochemist who advised Apollo astronauts gathering lunar samples and has been studying those samples ever since.
"That means you've got a lot of water stuck around in this glass that we never even thought too much about before," says Dr. Taylor, who was a member of the research team.
The notion that the moon has water or hydroxyls dates back at least to the early 1960s, when researchers at the California Institute of Technology proposed that water ice might exist in the perpetually dark – and frigid – depths of craters at the moon's poles. These were suggested as the final resting places for water ice deposited by collisions between the moon and comets.
Water's presence on the moon is of more than academic interest. Split into oxygen and hydrogen, water represents a source of raw material for rocket fuel. Finding water on the moon in a form that would be relatively easy to exploit would open the possibility of using the moon as a destination as well as a staging area for human exploration beyond low-Earth orbit and living off the “land” while doing it.