The second human lunar landing. The Apollo 12 Saturn V rocket was struck by lightning twice during launch, the first time 36 seconds after liftoff. The first lightning strike caused a loss of almost all instrumentation in the Command Module and knocked all three fuel cells (critical to the mission) offline. Communication with Mission Control became garbled. A second lightning strike struck the rocket 52 seconds after liftoff. Thankfully, the Saturn V flight computer was isolated from the Apollo crew vehicle and kept flying perfectly. A single flight controller in Mission Control remembered a one-off test malfunction of the Command/Service Module signal conditioning electronics (SCE) assembly and made an on-the-fly, educated call to switch the SCE to its backup power source. The physical switch was unknown to the Flight Director and the mission's Commander. It was Lunar Module pilot Alan Bean who remembered the SCE to AUX button from a training incident a year prior when the same simulated failure occurred. After making it safely to Low Earth Orbit, the crew checked over the spacecraft, got the fuel cells back online, and confirmed there was not serious damage to systems. On the ground, flight controllers were worried the pyrotechnics on the parachutes may have fired when the lightning strikes occurred and would therefore not deploy on landing. Since nothing could be done about this, they sent Apollo 12 to the Moon without telling the crew. The mission safely landed very close to NASA's Survey 3 lunar lander; pieces of the probe were removed for return to Earth. After a successful mission, the crew returned to Earth; the parachutes worked perfectly.