In 1961, only a few months after President John F. Kennedy announced the goal of putting astronauts on the moon by the end of the 1960s, North American Aviation, which leased the Downey site from NASA, won the contract for the cone-shaped command module and the accompanying service module, which provided the propulsion and power. North American also won the contract to build the second stage of the gigantic Saturn 5 rocket.

Grumman won the lunar lander contract a year later.

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To appreciate the whiplash pace of aerospace progress during the 20th century, look at the life of Ernest Finamore. When he joined Grumman as a teenager during World War II, he riveted together TBF Avenger torpedo bombers, propeller warplanes with a top speed of 275 miles per hour and a range of 1,000 miles. By his 40s, he was a lead inspector for the construction and testing of the lunar lander, which would make history a quarter million miles from Earth.

Mr. Finamore, 93, shared a memory of the day he bumped into Neil Armstrong.

As he was working in the lunar module cockpit there was a knock on the door. “The guy comes in and bumps shoulders and all,” Mr. Finamore said. “And then I took another slow look and he says, ‘Hi, I’m Neil Armstrong.’”

Mr. Armstrong looked out the window and asked about a device called a touchdown rod, which would register when the spacecraft had landed. Mr. Armstrong complained that it might bend up and become ensnared with the ladder that he and Mr. Aldrin would climb down.

An engineer was called in and agreed, and the rod was removed. (The rods on the other three landing pads remained.)

Mr. Armstrong also laughed at the two stools in the cockpit. Mr. Finamore recalled him asking, “‘When I’m going to have time to sit down?’ I said, ‘Oh, O.K. Take the stools; save more weight.’ This is how things happened.’”