AS15-91-12366 (31 July-2 Aug. 1971) --- The crater Posidonius at the northeastern edge of the Sea of Serenity, was photographed with a 70mm handheld Hasselblad from the Command and Service Module (CSM) by astronaut Alfred M. Worden, command module pilot, in lunar orbit. While Worden remained with the CSM in lunar orbit, astronauts David R. Scott and James B. Irwin descended in the Lunar Module (LM) "Falcon" to explore the lunar surface.