'Loneliest' Astronaut Michael Collins, Who Flew on Apollo 11 Mission to the Moon, Dies at 90

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Michael Collins, who holds an important place in history as one of the astronauts who helped humans walk on the Moon for the first time, died of cancer Wednesday, his family announced. He was 90.

It was in July 1969 that Collins, Neil Armstrong and Buzz Aldrin ventured to the Moon as part of NASA's Apollo 11 mission. Collins — the mission's command module pilot — remained in orbit as Armstrong and Aldrin became the first humans to walk on the Moon's surface.

"He spent his final days peacefully, with his family by his side. Mike always faced the challenges of life with grace and humility, and faced this, his final challenge, in the same way. We will miss him terribly," his family said in a statement posted on social media. "Yet we also know how lucky Mike felt to have lived the life he did. We will honor his wish for us to celebrate, not mourn, that life."

"Please join us in fondly and joyfully remembering his sharp wit, his quiet sense of purpose, and his wise perspective, gained both from looking back at Earth from the vantage of space and gazing across calm waters from the deck of his fishing boat," the statement continued.

During his career as an astronaut, Collins spent 266 hours in space during two space flights, according to NASA.

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Acting NASA Administrator Steve Jurczyk said Wednesday the nation "lost a true pioneer and lifelong advocate for exploration."

"As pilot of the Apollo 11 command module – some called him 'the loneliest man in history' – while his colleagues walked on the Moon for the first time, he helped our nation achieve a defining milestone," Jurczyk said, in part.

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"NASA mourns the loss of this accomplished pilot and astronaut, a friend of all who seek to push the envelope of human potential," he added. "Whether his work was behind the scenes or on full view, his legacy will always be as one of the leaders who took America's first steps into the cosmos. And his spirit will go with us as we venture toward farther horizons."

According to NPR, Collins gained the nickname "the loneliest man" in history during the Apollo 11 flight. While Armstrong and Aldrin explored the Moon together, Collins remained in communication with NASA controllers aboard the spacecraft.

But as the ship reached the backside of the Moon, Collins was temporarily cut off from communication with NASA. For a short time, some 240,000 miles away from Earth, he was truly alone.

"I am alone now, truly alone, and absolutely isolated from any known life," Collins once told NASA of his time alone in the spacecraft. "I am it. If a count were taken, the score would be three billion plus two over on the other side of the moon, and one plus God knows what on this side."

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Aldrin — who is now the last surviving Apollo 11 member — posted a picture of himself, Collins and Armstrong (who died in 2012), to Twitter, along with a heartfelt message to his friend.

"Dear Mike, Wherever you have been or will be, you will always have the Fire to Carry us deftly to new heights and to the future," Aldrin wrote. "We will miss you. May you Rest In Peace."