March 27, 2013
Lunar Reconnaissance Orbiter Detects Hydrogen, Mercury From Twin GRAIL Impacts
redOrbit Staff & Wire Reports - Your Universe Online
Using instruments on board the Lunar Reconnaissance Orbiter (LRO), NASA officials were able to detect mercury and hydrogen in the gas plumes that arose following the impact of the twin Gravity Recovery and Interior Laboratory (GRAIL) spacecraft last December, the US space agency announced on Tuesday.
The LRO´s Lyman Alpha Mapping Project (LAMP) also measured the time evolution of those gases as they rapidly expanded into the vacuum of space at near-escape velocity. The impact came after the GRAIL vehicles crashed onto the lunar surface in the north pole region on December 17 — an intentional move made by NASA officials after the twin spacecrafts successfully completed their prime and extended science missions.
"While our results are still very new, our thinking is that the hydrogen detected from the GRAIL site might be related to an enhancement at the poles caused by hydrogen species migrating toward the colder polar regions," Dr. Kurt Retherford, LAMP principal investigator and a principal scientist at the Southwest Research Institute (SwRI) — which developed the instrument — said in a statement.
Back in October 2009, LAMP also observed the impact of NASA's Lunar Crater Remote Observation and Sensing Satellite (LCROSS), which resulted in the first confirmation that atomic mercury, molecular hydrogen and carbon monoxide, and small amounts of calcium and magnesium, were present on the moon.
By combining the results of those observations with those from the GRAIL impact, LAMP team member and SwRI senior research scientist Dr. Thomas Greathouse believes that scientists could learn more about hydrogen and water near the lunar poles.
“We have begun to understand that the amount of water ice near the polar regions is higher than was previously thought, but we don't fully understand how it gets there,” he added.
According to the SwRI, which developed the instrument, LAMP uses a novel method in which it can study the permanently shadowed regions of the moon, which makes it the ideal tool for looking into the darkest areas of the moon and study its atmosphere.
It typically observes the night-side lunar surface using light from nearby space, which covers all of the features in a soft glow. That glow is invisible to the human eye, but can be seen by LAMP as it reflects off the moon´s surface.
Now, however, LAMP has become the first instrument to detect these emissions (which are known as Lyman-alpha emissions) from native lunar atomic hydrogen gas released by the impact.