June 20, 2013
Research Sheds Light On How Radiation Changes The Chemistry Of Water Ice In The Solar System
Brett Smith for redOrbit.com - Your Universe Online
Researchers from NASA and the University of New Hampshire believe they have shed light on the cosmic activity occurring on the dark side of the moon.
The moon's permanently shaded side has never been exposed to the sun, allowing for the formation of a fairly undisturbed layer of lunar soil.
Scientists first discovered molecular hydrogen on the moon as a result of NASA's Lunar Crater Observation Sensing Satellite (LCROSS) mission, which crash-landed the satellite's used Centaur rocket into the moon at 5,600 miles per hour. The rocket slammed into the Cabeus crater, located in the permanently shaded area of the moon.
The resulting collision drove a massive debris plume high above the lunar surface. The orbiting LCROSS detected the somewhat expected results of water vapor and water ice. Meanwhile NASA´s Lunar Reconnaissance Orbiter (LRO), already circling the moon, surprisingly picked up traces of molecular hydrogen.
"After the finding, there were a couple of ideas for how molecular hydrogen could be formed but none of them seemed to work for the conditions in the crater or with the rocket impact," said co-author Andrew Jordan, a researcher at the University of New Hampshire's Institute for the Study of Earth, Oceans, and Space. "Our analysis shows that the galactic cosmic rays, which are charged particles energetic enough to penetrate below the lunar surface, can dissociate the water, H2O, into H2 through various potential pathways."
Jordan and his colleagues reached their findings using data gathered by the LRO's Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument. Jordan's UNH colleague Nathan Schwadron was reportedly the first to suggest cosmic energy particles as the cause for the creation of molecular hydrogen, according to a recent statement.
"We used the CRaTER measurements to get a handle on how much molecular hydrogen has been formed from the water ice via charged particles." Jordan said. Using the CRaTER data, the team created computer models that revealed cosmic particles forming between 10 and 100 percent of the hydrogen molecules measured by the NASA orbiter.
To refine their figures, the study authors said particle accelerator experiments on frozen water could be performed to more accurately determine the number of chemical reactions caused by specific levels of cosmic rays and solar energetic particles.
"This result indicates the importance of radiation exposure to the volatile chemicals stored in lunar cold traps, which has implications for our understanding of the history of the solar system as well as its future exploration," said co-author Timothy Stubbs, research scientist from NASA Goddard.
The LRO also contains the Lyman Alpha Mapping Project (LAMP), which maps the entire lunar surface in the ultraviolet spectrum in pursuit of surface ice and frost in the moon's polar regions. It also captures images of the moon's permanently shadowed regions that are only illuminated only by starlight.