This is the 21st in an exclusive series of 50 articles, one published each day until July 20, exploring the 50th anniversary of the first-ever Moon landing. You can check out 50 Days to the Moon here every day.
Apollo 8 was the triumphant Christmas Eve flight of the Apollo capsule, with crew members Frank Borman, Jim Lovell, and Bill Anders. It flew to the Moon, orbited 10 times, the astronauts read to the world from Genesis during a live TV broadcast, and the capsule returned—all virtually flawlessly.
Apollo 8 was an improvised mission: it flew without a lunar module, because they were behind schedule, and there wasn’t one ready for space. The goal was, quite literally, to get America to the Moon before the Russians could fly there.
One of Apollo 8’s key missions was to test the accuracy and capability of the spacecraft’s flight computers and instruments. Could the newly created computers navigate with absolute precision to the Moon, and then bring the astronauts back to Earth with that same precision? Could the first global tracking network follow its path and communicate with it without any interruption?
Coming home, the computer’s ability to fly the spacecraft was just as perfect. In fact, the computer performed so well, it caused a problem—and provoked a cautionary memo.
Bill Tindall was a senior NASA official in Houston, a good-humored genius of space navigation and mission planning. Part of his job was to make sure the spaceships got to exactly where NASA wanted them to go.
After Apollo 8’s splashdown, Tindall wrote what was for him a slightly testy letter to Jerry Hammack, NASA’s head of recovery operations, explaining the problem and the solution.
Apollo 8 had flown 580,000 miles and landed just 1.6 miles from its target point in the Pacific Ocean—while literally passing right over the aircraft carrier Yorktown on its way into the ocean. So close, then, that the man in charge of all that navigation wanted the U.S. Navy to stand off the aircraft carriers so that future spaceships didn’t accidentally land right on the flight deck.
As it would turn out, Apollo 8 set the standard for that kind of landing accuracy.
Eight more Apollo missions flew all the way to the Moon and back. Only three landed two miles or more from their target point in the ocean. Four landed 1.5 miles from the target or less. Apollo 14 landed just 0.7 miles from its target.
In almost every case, the aircraft carrier picking up the astronauts—and their capsules—were kept four miles or more from the inbound spaceship.

Charles Fishman, who has written for Fast Company since its inception, has spent the past four years researching and writing One Giant Leap, a book about how it took 400,000 people, 20,000 companies, and one federal government to get 27 people to the Moon. (You can order it here.)
For each of the next 50 days, we’ll be posting a new story from Fishman—one you’ve likely never heard before—about the first effort to get to the Moon that illuminates both the historical effort and the current ones. New posts will appear here daily as well as be distributed via Fast Company’s social media. (Follow along at #50DaysToTheMoon).