Harrison Schmitt credits the image to the entire Apollo 17 crew. While on the Moon's surface, Schmitt — the only geologist in the astronaut corps — collected the rock sample designated Troctolite 76535, which has been called "without doubt the most interesting sample returned from the Moon". Among other distinctions, it is the central piece of evidence suggesting that the Moon once possessed an active magnetic field. As he returned to the Lunar Module before Cernan, Schmitt is the next-to-last person to have walked on the Moon's surface. After the completion of Apollo 17, Schmitt played an active role in documenting the
Tsiolkovskiy (crater) in Mendeleev crater far to the northeast are called Catena Mendeleev, and the row points directly at Tsiolkovsky. For this reason the craters are believed to be secondaries from the Tsiolkovsky impact. This feature was discovered on photographs sent back by the Russian spacecraft Luna 3, and was subsequently imaged by several of the American Lunar Orbiters and then by Apollo astronauts. Apollo 17 Astronaut Harrison "Jack" Schmitt and other scientists (Schmitt was the only trained scientist, a geologist, to walk on the moon) strongly advocated Tsiolkovskiy as the landing site of Apollo 17, using small communications satellites deployed from