Apollo 6 (SA-502): Unmanned Saturn V mission. Unlike the previous mission, several things went wrong: The first stage (SI-C) developed longitudinal vibrations (Pogo Effect) at 125 seconds for 10 seconds; after 4.5 minutes, engine 2 shut down, and a second later, engine 3 did too. The IU immediately corrected the attitude to compensate for the shutdown of two engines and ordered the other three to burn longer to correctly reach the programmed orbit. Finally, the third stage failed to ignite properly. The cause and remedy for all the malfunctions, in a joint effort between NASA, universities, and contractors, was found in the record time of just a few months. The automatic in-orbit imaging also had problems, but one succeeded and brought spectacular images of the Saturn V’s staging back to Earth. The Saturn V had several cameras attached, destined to be ejected and later recovered. Three of the four cameras on board the S-IC (first stage) failed to eject and were therefore destroyed, and only one of the two cameras on the S-II (second stage) was recovered.
