Harrison “Jack” Schmitt was born in 1935 and grew up in the copper mining country of Santa Rita and Silver City, New Mexico. He earned a geology degree at Caltech in 1957, mapped rock formations in Norway as a Fulbright scholar, received a Harvard PhD in 1964 and helped develop lunar field techniques for NASA with the U.S. Geological Survey in Arizona. Selected in NASA’s first scientist astronaut group in 1965, he completed Air Force jet pilot training and was slated for Apollo 18. When Apollo 18 and 19 were canceled, geologists lobbied for a scientist on the final flight, and in August 1971 NASA assigned him to Apollo 17, replacing test pilot Joe Engle. In December 1972 he landed in the Taurus-Littrow valley with Gene Cernan.

The troctolite sample 76535 he collected became key evidence that the Moon once had a magnetic field. Schmitt left NASA in August 1975, won a U.S. Senate seat from New Mexico as a Republican by defeating a two term incumbent and chaired a subcommittee on science, technology and space. In 1982 Jeff Bingaman beat him during a recession by asking what he had done for voters lately. He later taught engineering physics at the University of Wisconsin-Madison and wrote a 2006 book advocating mining helium-3 on the Moon for fusion power. He resigned as chair of the NASA Advisory Council and quit the Planetary Society in 2008, and in opinion pieces he rejected the scientific consensus that recent warming is mainly human caused.

• He is the only practicing scientist among the 12 people who walked on the Moon, and the second to last to leave its surface.
• He claims he took the Blue Marble photograph; Cernan and Ron Evans also claim it, and NASA credits the whole crew.
• His 2011 appointment as New Mexico energy secretary collapsed after he refused the required background investigation.
• In 2018 he advised a company that flew a commercial space Wi-Fi device on a Blue Origin rocket.
• In July 2026 he was honored on the National Mall for the Semiquincentennial alongside the Artemis II crew.