>>18862305 lb

>Ebb and Flow

The Gravity Recovery and Interior Laboratory (GRAIL) was an American lunar science mission in NASA's Discovery Program which used high-quality gravitational field mapping of the Moon to determine its interior structure. The two small spacecraft GRAIL A (Ebb) and GRAIL B (Flow)[4][5] were launched on 10 September 2011 aboard a single launch vehicle: the most-powerful configuration of a Delta II, the 7920H-10.[1][6][7] GRAIL A separated from the rocket about nine minutes after launch, GRAIL B followed about eight minutes later. They arrived at their orbits around the Moon 25 hours apart.[8][9] The first probe entered orbit on 31 December 2011 and the second followed on 1 January 2012.[10] The two spacecraft impacted the Lunar surface on December 17, 2012.[11]

https://en.wikipedia.org/wiki/GRAIL