A panoramic view of Taurus–Littrow taken in December 1972, during the Apollo 17 lunar mission. This lunar valley is located on the near side of the Moon, along a ring of mountains on the southeastern edge of Mare Serenitatis. Toward the right, geologist-astronaut Harrison Schmitt prepares to take a sample. Data collected on Apollo 17 show that the valley is composed primarily of feldspar-rich breccia in the large massifs surrounding the valley and basalt underlying the valley floor, covered by an unconsolidated layer of regolith, or mixed materials, formed by various geologic events.Photograph: Eugene Cernan