The sons eventually followed their own paths. Mark became a software developer. Rick studied marine biology and became an animal trainer, before shifting gears and joining his brother at a software start-up.

“I think a lot of times, the son wants to outdo the father,” Rick said. “I pretty much learned quickly that that wasn’t going to be something I needed to worry about. First man on Mars would probably be the only chance I would have, and that was not a realistic career goal. I was able to let go of that issue pretty early on, and I don’t feel that ever bothered me.”

[Read The Times obituary for Neil Armstrong from 2012.]

In later years, Neil Armstrong largely withdrew from public life, but they dispute perceptions of him as a recluse. “He was a funny guy,” Rick said.

Mark recalled being at a talk that his father was giving at the Sydney Opera House around 1977. Neil Armstrong, the program said, did not exercise because he thought everyone has a set number of heartbeats and he did not want to waste any — something he had said, likely in jest, in 1969 to Life magazine.

Mark said his father walked onto the stage and said, "Before I get started, I want to clear one thing up." Mr. Armstrong took off his jacket, dropped down to do about 20 push-ups, got up, put his jacket on, and without further comment, launched into his prepared talk.