John Young, who has died at the age of 87, was the longest-serving Nasa astronaut, making two flights to the moon and piloting the first test flight of the Space Shuttle.
By the time Young was due to command Apollo 16, in April 1972, the Soviet Union's Lunokhod robot was exploring the Sea of Rains and doubts were expressed as to whether the cost of a fifth US moon landing was justified.
The astronauts wanted to counter such misgivings by landing in the rugged Aristarchus area near the lunar south pole.
Nasa chiefs thought this was too risky, and Young and his companions, Ken Mattingly and Charlie Duke, had to be content with aiming at the mountainous Descartes region, which geologists hoped - in vain - would prove to be volcanic.
It was just as well, for the flight was plagued with mechanical problems. Young and Duke were eventually given the go-ahead to land, and a global audience witnessed their three excursions aboard the lunar rover, including a celebratory "lunar grand prix", during which Young drove the rover in circles at its top speed of 17km/h, skidding it to test wheel grip.
John Watts Young was born in San Francisco on September 24 1930, and brought up in Orlando, Florida, where he graduated from high school.
After studying aeronautical engineering at the Georgia Institute of Technology, he joined the US Navy, serving in a destroyer during the Korean War, after which he was sent on flight training.
As a test pilot he set records for altitude climbs in the Phantom jet fighter, and rose to the rank of captain. Selected by Nasa for the second intake of astronauts in 1962, his six missions enabled him to achieve multiple firsts.
On his debut flight in the two-person Gemini spacecraft in 1965, Young operated the first space-borne computer, but earned an official reprimand for smuggling a corned beef sandwich on board.
When the crew of Gemini 10, the last in the series, were killed in a plane crash, Young and Michael Collins replaced them. Young's third flight was aboard Apollo 10, which flew around the moon in May 1969 and staged a rehearsal of moon landing procedures.
After his own successful moon landing, Young spent the following six years helping to design and develop the Space Shuttle.
He piloted the first test flight, followed by the first horizontal landing of a spacecraft in the Californian desert.
His last mission was in 1983.
He is survived by his wife Susy and a son and a daughter from a previous marriage. 
1930-2018..