American astronaut John Young, who walked on the moon during the Apollo 16 mission and commanded the first space shuttle mission, has passed away, NASA announced on Saturday.

Young died from complications of pneumonia at the age of 87 on Friday.

He completed six spaceflights during his career, which was a world record at the time of his retirement. He is the only person to go into space as part of the Gemini, Apollo and space shuttle programs.

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During this career spanning three generations of spaceflight, he spent a total of 835 hours in space.

In a post on Twitter, NASA called Young their "most experienced astronaut."

"Today, NASA and the world have lost a pioneer," acting NASA Administrator Robert Lightfoot said in a statement. "John Young was at the forefront of human space exploration with his poise, talent, and tenacity. He was in every way the 'astronaut's astronaut.'"

Young was born in San Francisco, California, but grew up in Orlando, Florida. As a child, his favorite hobby was building model airplanes. He went on to study aeronautical engineering at Georgia Tech, where he graduated with highest honors in 1952.

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He then joined the Navy and, after a year's service aboard a destroyer, was sent to flight training.

After flying fighter planes for four years, he completed test pilot training and served three years at the Navy's Air Test Center. Then, after hearing President Kennedy's proposal in 1961 to land a man on the moon and return him safely to Earth, he decided to take his love of flying even further.

Young began his career at NASA in 1962, when he was selected from hundreds of young pilots to join NASA's second astronaut class.

In March 1965, he made his first flight as an astronaut, joining Gus Grissom on Gemini 3, the first manned flight of that program.

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Young commanded the Gemini 10 mission in July 1966 and in May 1969 served as command module pilot on Apollo 10, flying all the way to the moon with crewmates Tom Stafford and Gene Cernan. 

Young made a return trip to the moon as commander of Apollo 16 in April 1972. "The moon is a very nice place," Young said.

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In April 1981, he commanded Space Shuttle Columbia on its — and the Shuttle program's — first flight, STS-1. It was the first time a piloted spacecraft was tested in space without previous orbital flights with nobody on board. 

When asked what moment in his career was most memorable at his retirement from NASA in 2004, he replied, "I liked them all."

law/msh (dpa, Reuters)