Geological Chronicle
Mare Fecunditatis sits in the eastern half of the visible Moon. Its underlying basin formed in the Pre-Nectarian epoch, while basin material surrounding the mare dates to the subsequent Nectarian epoch. Volcanic mare material erupted later during the Upper Imbrian epoch. This basalt layer is relatively thin compared to neighboring maria.
The basin is overlapped with the Nectaris, Tranquillitatis, and Crisium basins. Where the Fecunditatis basin meets Nectaris basin along its western edge, the area is faulted by arcuated grabens. The crater Langrenus and Sinus Successus lie along the eastern edge of the mare, while the craters Messier and Messier A lie near the center.
Unlike many other lunar maria, Mare Fecunditatis has no mass concentration (mascon), or gravitational high, in its center. Doppler tracking of the five Lunar Orbiter spacecraft identified central mascons in maria such as Serenitatis or Imbrium in 1968, but Fecunditatis showed none. Later orbital surveys by Lunar Prospector and GRAIL mapped the gravity field at higher resolution and showed an irregular pattern.
The mare was the site of a milestone in robotic exploration. In September 1970, the first automated sample return took place via Luna 16 from Mare Fecunditatis.