He did not mind his solitary time aboard the spacecraft, which was named Columbia.

“I had this beautiful little domain,” Mr. Collins said. “It was all mine. I was the emperor, the captain of it, and it was quite commodious. I had warm coffee, even.”

Unlike half a billion people on Earth, Mr. Collins did not see the broadcast of Mr. Armstrong’s first steps on the moon.

There was no television in the command module. Even if there were, he would still not have seen it. Mr. Collins was above the far side of the moon at that moment, cut off from all communications, and he missed Mr. Armstrong’s legendary words: “That’s one small step for man , one giant leap for mankind.”

Mr. Collins spoke of his life as a NASA astronaut in the 1960s in a series of interviews, two with New York Times journalists and one with the playwright J. T. Rogers as part of research for a play commissioned by The Times. He discussed other questions he has often been asked, too.

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What was the mood as you sat on the launchpad awaiting liftoff on July 16, 1969?

“I was thinking of per diem, you know, how many dollars per mile we’d be paid for this voyage,” he joked.