When the first two humans walked on the lunar surface, Michael Collins sat alone in the command module and drifted behind the dark side of the Moon. As he did, all communications ceased with Earth, blocked by the Moon, leaving him completely cut off from humanity and hundreds of thousands of miles from home.

"I am alone now, truly alone, and absolutely isolated from any known life," Collins wrote in his 1974 book Carrying The Fire: An Astronaut's Journeys. "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."

It's an experience shared by just six other people in history, but Collins was remarkably unfazed by the experience, and always found it odd how the media portrayed him as the "loneliest man in history".

"I feel this powerfully – not as fear or loneliness – but as awareness, anticipation, satisfaction, confidence, almost exultation. I like the feeling," he wrote.

"Outside my window I can see stars – and that is all. Where I know the moon to be, there is simply a black void; the moon’s presence is defined solely by the absence of stars. To compare the sensation with something terrestrial, perhaps being alone in a skiff in the middle of the Pacific Ocean on a pitch-black night would most nearly approximate my situation."

On the Apollo 11 mission in 1969 that would see the first people land on the Moon, Collins was in the command module Columbia for 21 hours while Buzz Aldrin and Neil Armstrong made their descent to the surface and had a historic stroll. Keeping him occupied were thoughts of animals waiting for him back on Earth.

"What I was worried about was the white mice," he said in 2018. When the crew returned from their journey, they would be quarantined for two weeks, just in case they had picked up contagions on the Moon (though this was deemed extremely unlikely, it's better safe than sorry). 

"If one of those poor little things didn't do too well, we were in deep trouble, we might've brought back some pathogen. So every time I was asked, 'weren't you the most lonely one?' I think, 'Oh God, those poor little white mice, I hope they're doing alright.'"

As Armstrong and Aldrin returned from the Moon, Collins took a photograph of Earth, our satellite, and the Eagle lunar module. The only human or animal alive at that time that wasn't within the frames of the photograph was Collins himself.

About his historic mission to the Moon, Collins was very humble.

"When the history of our galaxy is written, and for all any of us know it may already have been, if Earth gets mentioned at all it won't be because its inhabitants visited their own moon," he wrote in his 1988 book Liftoff: The Story of America's Adventure In Space.

"That first step, like a newborn's cry, would be automatically assumed. What would be worth recording is what kind of civilization we earthlings created and whether or not we ventured out to other parts of the galaxy."

An earlier version of this article was published in April 2021.