Nasa said Young died at home in Houston on Friday night following complications from pneumonia.
The space agency said Young was the only agency astronaut to go into space as part of the Gemini, Apollo and space shuttle programs, and the first to fly into space six times. He was the ninth man to walk on the moon.
Young was in Nasa’s second astronaut class, chosen in 1962, along with the likes of Neil Armstrong, Pete Conrad and James Lovell.
“Today, Nasa and the world have lost a pioneer,” Nasa administrator Robert Lightfoot said in a statement. “Astronaut John Young’s storied career spanned three generations of spaceflight.
“John was one of that group of early space pioneers whose bravery and commitment sparked our nation’s first great achievements in space.”
Counting his takeoff from the moon in 1972 as commander of Apollo 16, Young’s blastoff tally stood at seven, for decades a world record. He flew twice during the two-man Gemini missions of the mid-1960s, twice to the moon during Nasa’s Apollo program, and twice more aboard the new space shuttle Columbia in the early 1980s.
He spent his last 17 years at Nasa’s Johnson Space Center in Houston in management, focusing on safety issues. He retired at the end of 2004.
Robert Crippen, Young’s co-pilot on Columbia’s successful maiden voyage in 1981, said flying with Young was “a real treat”.
“Anybody who ever flew in space admired John,” said Crippen, a close friend who last spoke to Young a few months ago.
The US astronaut Terry Virts said in a tweet: “Rest In Peace John Young. You were one of my heroes as an astronaut and explorer and your passion for space will be missed.”
The retired Canadian astronaut Chris Hadfield echoed that on Twitter, saying: “John Young is one of my heroes, an astronaut’s astronaut, a fearless individual and a good friend. Godspeed.”
The retired US astronaut Scott Kelly said he was saddened by the loss and called Young in a tweet “the astronauts’ astronaut, a true legend”.
“Fair winds and following seas, Captain,” he added.
Bush said he and his wife Barbara Bush “join our fellow Americans and many friends in the space community in mourning the loss”.
“John was more than a good friend,” Bush said. “To us, he represented the best in the American spirit always looking forward, always reaching higher.”
Bush also said: “John leaves a tremendous legacy of accomplishment, in addition to his wonderful family. May his memory serve to inspire future generations of explorers to dare greatly, act boldly, and serve selflessly.”
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