On 18 June 2009, NASA launched the Lunar Reconnaissance Orbiter (LRO) to map the surface of the Moon and collect measurements of potential future landing sites as well as key science targets. After two and a half years in a near-circular polar orbit, LRO entered an elliptical polar orbit on 11 December 2011 with a periapsis (point where the LRO is closest to the surface) near the south pole, and t