Research conducted by former graduate student Alice DeSimone, under the guidance of Professor Thomas Orlando of the School of Chemistry and Biochemistry, intended to measure the impact of solar photonic action on water molecules on the lunar surface has yielded a set of benchmark measurements that other astrochemists and physicists can use to calculate the likely volumes of water of other solar system bodies.

Using and in-house built ultra-high pressure vacuum to simulate the atmospheric conditions of space, the team bombarded a lunar sample with ultraviolet (157 nm) photons and recorded the photodesorption of water molecules in the sample. They either came off with a cross section of ~ 6 x 10−19 cm2  or broke apart with a cross section of  ~ 5  x 10−19 cm2.. According to the team’s measurements, approximately one in every 1,000 molecules leave the lunar surface simply due to absorption of UV light. This relatively large number establishes that solar UV photons are likely removing water from the moon’s surface.

“The cross section is an important number planetary scientists, astrochemists and the astrophysics community need for models regarding the fate of water on comets, moons, asteroids, other airless bodies and interstellar grains,” said Orlando regarding the measurements.

For more information on this research follow this link to Georgia Tech Research News.
To read the journal article by DeSimone and Orlando, follow this link to the Journal of Geophysical Research.