Ronald Ellwin Evans Jr. was an American electrical engineer, aeronautical engineer, officer and aviator in the United States Navy, and NASA astronaut. As Command Module Pilot on Apollo 17 he was one of the 24 astronauts to fly to the Moon, and one of 12 people to fly to the Moon without landing.

Apollo 17 was the eleventh and final mission of NASA's Apollo program, the sixth and most recent time humans have set foot on the Moon or traveled beyond low Earth orbit. Commander Gene Cernan and Lunar Module Pilot Harrison Schmitt walked on the Moon, while Command Module Pilot Ronald Evans orbited above. Schmitt was the only professional geologist to land on the Moon; he was selected in place of Joe Engle, as NASA had been under pressure to send a scientist to the Moon. The mission's heavy emphasis on science meant the inclusion of a number of new experiments, including a biological experiment containing five mice that was carried in the command module.