April 28 (UPI) -- Michael Collins, a former NASA astronaut who was part of the first moon landing mission of Apollo 11 in 1969, died on Wednesday. He was 90.
Collins was part of Apollo 11's three-man crew, but unlike Neil Armstrong and Edwin "Buzz" Aldrin, he never walked on the moon. He was sometimes known as the "forgotten astronaut."
"Today the nation lost a true pioneer and lifelong advocate for exploration in astronaut Michael Collins," Acting NASA Administrator Steve Jurczyk said in a statement Wednesday.
"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."
Collins' death leaves Aldrin as the last remaining survivor from the historic Apollo 11 mission. Armstrong died in 2012.
Aldrin tweeted Wednesday afternoon: 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. We will miss you. May you Rest in Peace.
The tweet carried the hashtage #Apollo11.
Collins had been battling cancer. A statement released by his family said: "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."
In 1969, while Armstrong and Aldrin left the main capsule in a craft headed to the lunar surface, Collins radioed, "You cats take it easy."
Collins would circle the moon alone in the command module, 60 miles above the lunar surface, while Armstrong and Aldrin set down on the moon. He had prepared a 117-page list of contingencies in the event of problems.
Aldrin and Armstrong were on the moon's surface for about 22 hours, but only spent a couple hours outside the lunar vehicle.
"The view from the moon of tiny Earth is something I'll always bring with me," Collins told UPI in 2019 during the run up to the mission's 50th anniversary.
"It was tiny but very memorable. Blue and white. It seemed to project a quality of fragility -- which, unfortunately, has turned out to be quite true."