GRAIL Impacts on the Moon: Plumes of Gas Detected
A science instrument onboard NASA’s Lunar Reconnaissance Orbiter (LRO) detected plumes of gas rising from the December 17 impact on the Moon of the space agency’s twin GRAIL spacecraft.
Viewing the impact sites, LRO’s Lyman Alpha Mapping Project (LAMP) aboard LRO detected the presence of mercury and hydrogen. The device and measured their time evolution as the gas rapidly expanded into the vacuum of space at near-escape velocities.
Following GRAIL’s successful prime and extended science missions, both spacecraft were maneuvered to hit a mountain near the lunar north pole last year, which was shrouded in shadow at the time.
The two satellites, named Ebb and Flow, used radio signals to precisely measure their separation as they flew in formation, one following the other in the same nearly circular polar orbit. These measurements allowed mission scientists to build up an accurate and detailed gravity map of the Moon.
Cold polar regions
LRO’s LAMP — developed by Southwest Research Institute (SwRI) — uses a novel method to peer into the darkness of the Moon’s permanently shadowed regions, making it ideal for observations of the Moon’s night-side and its tenuous atmospheric constituents.
“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,” said Kurt Retherford, LAMP principal investigator and a principal scientist at SwRI in a press statement.
According to Thomas Greathouse, a LAMP team member and SwRI senior research scientist: “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.”
Water on the Moon is an invaluable resource, one that can be used to make rocket fuel and supply future lunar outposts with oxygen and water.
For video clips showing the LAMP-gathered data, go to: