On This Day in Space: NASA Launched GRAIL Probes to Map Moon's Gravity on Sept. 10, 2011

Summary

On September 10, 2011, NASA launched the GRAIL mission, consisting of twin spacecraft Ebb and Flow, to map the moon's gravitational fields and study its interior structure. The mission successfully mapped lunar mascons, confirming their formation from ancient asteroid impacts, before the probes were intentionally crashed into the moon in December 2012.