The story of Apollo XI, the first mission to land men on the moon, is familiar to most of us. But what many people don't know is how close it came to being aborted in the last few seconds before landing.
As the Lunar Module began its descent to the surface of the moon, the Apollo Guidance Computer on board began sounding 1201 and 1202 alarms. Those alarms meant that the computer was overloaded and could not complete all its tasks; it would have to cancel some of those tasks. Of course, that could have been disastrous, or result in the astronauts having to abort the mission.