LRO is a robotic mission that set out to map the moon’s surface and, after a year of exploration, was extended with a unique set of science objectives. LRO observations have enabled numerous groundbreaking discoveries, creating a new picture of the moon as a dynamic and complex body.
LRO and the Lunar CRater Observation and Sensing Satellite (LCROSS) were launched on an Atlas V rocket on June 18, 2009, beginning a four-day trip to the moon. LRO spent its first three years in a low polar orbit collecting detailed information about the moon and its environment. After this initial orbit, LRO transitioned to a stable elliptical orbit, passing low over the lunar south pole.
Objectives and Discoveries
Distribution of Polar Ice
LRO collected evidence indicating that the moon’s polar regions are cold enough to retain water ice, especially in permanently shadowed regions (PSRs). LRO observations indicate subsurface hydrogen deposits in both sunlit regions and PSRs, and indicate the composition of gases released from the Cabeus crater PSR by the LCROSS impact.
Geological Dynamics and Diversity
LRO discovered a global population of young extensional and contractional landforms, which suggest that the moon has undergone relatively recent geological activity. LRO observed volcanic complexes formed by viscous lava, extending the history of volcanism on the moon, and found that the lunar crust is more complex than previously recognized.
Traces of Previous Explorers
LRO has imaged the effects of human and robotic activity
on the lunar surface, including the landing/impact sites of Ranger, Surveyor, Apollo, and the Soviet Luna missions. These images provide a baseline for the analysis of space weathering and contextualize the collection sites of lunar samples. The high-resolution images of the Apollo landing sites are an inspiring record of lunar exploration.
Space Environment Interaction
LRO measured galactic cosmic ray interactions with the moon during a period of high radiation intensity, enabling the estimation of the radiation dose to the lunar surface. LRO also created a proton albedo map of the moon and, for the first time, remotely detected the lunar helium atmosphere.
LRO data has been used to investigate the bombardment history of the moon, improving the age dating of landforms through high-resolution images. By assessing the relative ages of impact basins, scientists created a chronology of lunar impacts, improving our understanding of the ancient impactors that affected the inner planets of the solar system.