For Apollo 11 He Wasn’t on the Moon. But His Coffee Was Warm.

That he ended up on Apollo 11 was the serendipity of back surgery.

Mr. Collins was originally assigned to be command module pilot of Apollo 8, which became the first mission to orbit (but not land on) the moon. But he started having trouble walking, caused by disk herniation in his spine. James Lovell replaced Mr. Collins on Apollo 8.

The surgery was successful, and Mr. Collins was reassigned to Apollo 11.

He could have had a third spaceflight as commander of Apollo 17. But even before Apollo 11 launched, he decided he wanted to leave the program because life as an astronaut took him away from his family. He told Deke Slayton of the astronaut office, who had been one of the original Mercury Seven astronauts, “If everything goes exactly as planned, I’m out of here.”

After Mr. Collins left NASA in 1970, he served as assistant secretary of state for public affairs and then director of the National Air and Space Museum, overseeing the construction of the current building on the National Mall in Washington.

Today, Mr. Collins still remembers the view of the moon as they closed in.

“It filled up a whole window, and it was absolutely three-dimensional,” he said. “The lights a lot lighter, the darks a lot darker, the delineation of them so clear. The sunlight was behind, and the sunlight was cascading 360 degrees around the rim of the moon. It made the most glorious spectacle you’ve ever seen in your life.”

But it is the view of Earth from 230,000 miles away, blue and white with a smudge of tan, that made more of a mark on him. “The thing that really surprised me was that it projected an air of fragility,” he said. “And why, I don’t know. I don’t know to this day. I had a feeling it’s tiny, it’s shiny, it’s beautiful, it’s home, and it’s fragile.”