Solar wind particles likely source of water locked inside lunar soils
October 14, 2012

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.

But the origin of lunar surface water has remained unclear. Is it mainly the result of impacts from water-bearing comets and other chunks of space debris, or could there be other sources? Theoretical models of lunar water stability dating to the late 1970s suggest that hydrogen ions (protons) from the solar wind can combine with oxygen on the moon’s surface to form water and related compounds called hydroxyls, which consist of one atom of hydrogen and one of oxygen and are known as OH.

In an article published online Sunday in the journal Nature Geoscience, U-M’s Youxue Zhang and colleagues from the University of Tennessee and the California Institute of Technology present findings that support solar-wind production of water ice on the moon.

Read more: Solar wind particles likely source of water locked inside lunar soils — phys.org.

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