First Apollo to landing on moon

Apollo 11 lunar module pilot Buzz Aldrin stands on the moon near the American flag during NASA's historic first manned moon landing on July 20, 1969. Apollo 11 commander Neil Armstrong took the photo.

Credit: NASA

Apollo 11 was four minutes into its landing sequence when the terse words of its commander, Neil Armstrong, came from the speaker in Mission Control:

"Program alarm."

Buzz Aldrin, sitting next to Armstrong in the descending Lunar Module, stared at the frozen display on the computer, which read "1202." It was an error code, but for what? Controllers in Houston scanned their notes trying to figure out what the heck the problem was. But time was running short. [45th Anniversary of Apollo 11: Complete Coverage]

"Give us a reading on that program alarm, " Armstrong said. He sounded tense, but no more so than during the simulations. It was hard to grasp that a life-or-death struggle was playing out 240, 000 miles (386, 000 kilometers) from Earth, in a small, fragile machine descending rapidly to the moon. Communications were spotty; the computer was threatening to quit, and Gene Kranz, the flight director for this first lunar landing, felt Mission Control slip a bit further behind the power curve.

A risky moonshot

Most people knew that going to the moon was risky. Some outside of Mission Control, listening to the tense communication between the astronauts and Houston, understood what some of the urgency meant. But few, very few, knew the scope of the dangers that the crew faced. These were no longer theoretical; they were being played out in space at that very moment.

Key players in the landing of Apollo 11, including Kranz, related the stakes to me these many decades later. "We would either land on the moon, we would crash attempting to land, or we would abort, " he said simply. "The final two outcomes were not good."

That is an understatement on a grand scale.

The Apollo 11 lunar module Eagle is seen from the Columbia command module in this photograph by command module pilot Michael Collins on July 20, 1969. Aboard the Eagle, Apollo 11 commander Neil Armstrong and lunar module pilot Buzz Aldrin prepared to land on the surface of the moon for the first time.

Credit: NASA

Approaching the moon

Credit: by Karl Tate, Infographics Artist

The problems began immediately upon separation from the Command Module in which Armstrong, Aldrin and Michael Collins had ridden to the moon. (Collins would remain in the Command Module as Armstrong and Aldrin landed.) Mission Control was having trouble with the radio link to the Lunar Module.

"It was purely my decision how much information was enough, " Kranz recalled. "This is now going through my mind: 'Do I have enough information to continue?' And the answer is yes" — but barely. "I gave the crew the go for powered descent, " that is, to beginthe rocket-braked landing, "and we immediately lost communications again."

Aldrin had adjusted the antenna, and Mission Control had done what they could on their end, but the radio connection just kept on fading in and out. If it got much worse, Kranz would have to order an abort. [Apollo 11 Quiz: Are You a Moon Maven?]