Houston, we have a problem. This line was made famous by Tom Hanks portraying Jim Lovell in Apollo 13. But, this was not the first time that Jim Lovell reported an inflight problem to Houston.
Before Apollo 13, Jim Lovell was the Command Module Pilot for Apollo 8, the mission flew around the moon for the first time in December 1968. On the way back from the moon, the guidance computer suddenly reset itself to a location on the launch pad. His call to Houston was less dramatic, “For some reason, we suddenly got a Program 01 and no attitude light on our computer.”
He meant to initiate star alignment with star 01, but accidentally entered the command P01, which reset the position back to the mission origin. P01 was never intended to be used while in flight. No harm came from this error, the transcripts show that the procedure to correct it came 10 minutes later in the mission. Good thing they were on day 5 of the 6-day mission.
What is interesting to me, this issue was not a new one. Margaret Hamilton actually found it during a testing session on a Saturday when she brought her daughter, Lauren, into work. Lauren was playing with the computer simulator and entered that same command. Margaret raised the issue but the change board declined to authorize a fix because the astronauts are very well trained and would not make that same mistake.
How many times has this happened in bug reviews?
PS: Margaret fixed the issue before Apollo 11.
Want to try it yourself? You can geek out with a simulator of the guidance computer.