US space agency Nasa has paid tribute to American astronaut Thomas K Mattingly, who died on October 31. He was 87.
Mr Mattingly was best known for his efforts on the ground that helped to return the damaged Apollo 13 spacecraft safely back to Earth, in 1970.
The astronaut and two of his colleagues were meant to be the primary crew of the ill-fated mission, but were removed when Nasa medical officers feared that they had been exposed to rubella.
When the crew of the Apollo 13 Moon mission became stranded after their spacecraft suffered damage, the world followed the news anxiously.
Among the bright minds working on the ground, as mission control in Houston tried to bring the flight back home safely, was Mr Mattingly.
The replacement crew for the mission, which comprised James Lovell, Jack Swigert and Fred Haise, would eventually say what has now become a popular phrase: "Houston, we have a problem".
Bill Nelson, administrator of the US space agency Nasa, led the tributes to Mr Mattingly.
"Perhaps his most dramatic role at Nasa was after exposure to rubella just before the launch of Apollo 13," he said.
"He stayed behind and provided key real-time decisions to successfully bring home the wounded spacecraft and the crew of Apollo 13."
A liquid oxygen tank that was already damaged before the flight, which launched on April 11, 1970, caused the explosion of the craft as it was on its way to the Moon.
The landing module that the crew was meant to use to touchdown on the Moon became their lifeboat.
Mission control was quick in problem-solving, instructing the crew to turn off most of the electricity to make sure they would have enough power for their return journey.
They came up with five trajectories for the crew's trip back to Earth and also had engineers inside a mock up of the spacecraft to mimic every decision the astronauts were making.
It was meant to be the third human landing on the lunar surface but instead they looped around the Moon.
The crew made it home on April 17, splashing down in the South Pacific ocean.
The six-day trip helped to inspire Hollywood's Apollo 13 movie in 1995, with Mr Mattingly who was portrayed by actor Gary Sinise.
Mr Mattingly was also part of the Apollo 16 mission in 1972.
He served as the command module pilot and remained in lunar orbit, as his colleagues John Young and Charlie Duke landed on the Moon.
And, although he did not step foot on the Moon, he made history by performing the world's second ever deep-space walk.
Ten years later, Mr Mattingly served as spacecraft commander for space shuttle missions STS-4 and STS 51-C.
