Geological Chronicle
Mare Spumans (Latin for 'Foaming Sea') is an irregular lunar mare spanning 139 kilometers across the eastern near side of the Moon at 1.1° N, 65.1° E. The mare occupies elevated terrain directly south of Mare Undarum and southeast of the main Crisium impact basin. Spumans rests on a highland bench where volcanic lavas flooded fractures in the older Nectarian period crust.
The basalt plain dates to the Upper Imbrian epoch. Magma reached the surface through crustal faults created during the Crisium impact, filling low depressions between pre-existing crater walls. The mare is bordered by the crater Apollonius to the north and northwest and Maclaurin to the south. On the western edge of Spumans sits Petit (formerly known as Apollonius W), a bright impact crater surrounded by a distinct ray system extending over the dark mare floor. High-albedo lunar swirls also appear across the surrounding terrain, linked to localized crustal magnetic fields that shield the lunar soil from solar wind weathering.
During the Apollo program, northern Mare Spumans provided a landmark for lunar orbit navigation. Mission planners designated a small rayed crater at 1.7981° N, 65.0741° E as landmark A-1/11. On revolution 4 of Apollo 11 in July 1969, astronaut Michael Collins sighted this crater through the Command Module sextant to feed position data into the onboard guidance computer. Collins named the feature KAMP after his wife Patricia and children Kate, Ann, and Michael. In December 1972, the mapping camera on Apollo 17 photographed Mare Spumans and adjacent Mare Undarum from orbit.