July 20, 1969: What Actually Happened on the Moon

Apollo 11 launched from Kennedy Space Center on July 16, 1969, at 9:32 AM EDT. The Saturn V rocket was 111 meters tall and produced 7.6 million pounds of thrust at liftoff. Neil Armstrong, Buzz Aldrin, and Michael Collins were aboard.

Collins would remain in lunar orbit inside the Command Module *Columbia*. Armstrong and Aldrin descended in the Lunar Module *Eagle*.

The landing almost didn't happen.

**The 1202 alarm**

About 6,000 feet above the lunar surface, the guidance computer in Eagle began flashing a 1202 alarm — a code that nobody in the landing crew had seen before. Armstrong and Aldrin kept flying. Mission Control's 26-year-old guidance officer, Jack Garman, had documented the alarm just days before during a training exercise: it meant the computer was overloaded and dropping lower-priority tasks. "Go," said Steve Bales. The landing continued.

Then the landing zone appeared wrong. Armstrong was looking out the window at a crater filled with boulders — not a safe landing site. With roughly 30 seconds of fuel remaining, he took manual control and flew horizontally across the surface, searching for flat ground.

He found it. At 4:17 PM EDT on July 20, the *Eagle* touched down in the Sea of Tranquility. Aldrin said "Contact light." Armstrong said "The Eagle has landed." Charlie Duke at Mission Control replied: "Roger, Tranquility. We copy you on the ground. You've got a bunch of guys about to turn blue. We're breathing again."

**The moonwalk**

Armstrong climbed down the ladder and stepped onto the lunar surface at 10:56 PM EDT, July 20 (02:56 UTC, July 21). His exact words: "That's one small step for [a] man, one giant leap for mankind." The "a" was lost in transmission static; Armstrong always insisted he said it.

Aldrin joined him 20 minutes later. They planted the American flag — which required a wire frame to stay extended in the airless vacuum — collected 21.5 kilograms of rock and soil samples, deployed scientific instruments, and spent 2 hours and 31 minutes outside.

Collins, meanwhile, orbited overhead in *Columbia*, unable to see the landing site. He spent 21.5 hours flying solo — farther from any other human than anyone in history, on the far side of the Moon.

**What the Soviets were doing**

Two days before the landing, the Soviet Luna 15 probe was in lunar orbit, attempting to land, collect samples automatically, and return to Earth before Apollo 11. It crashed on July 21, while Armstrong and Aldrin were still on the surface.

The Soviet cosmonauts watched the Apollo 11 broadcast live, in what was an unusual breach of the usual Soviet practice of ignoring American successes. The N1 Moon rocket, which would have carried Soviet cosmonauts, had exploded catastrophically on July 3, 1969 — two weeks before Apollo 11's launch. The explosion destroyed the launch pad and was the largest accidental non-nuclear explosion in history at that point.

The race was over. The United States had won.

July 20, 1969: What Actually Happened on the Moon

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