Astronaut Alan Bean is remembered for being the fourth human to walk on the moon, one of the first Americans to live aboard a space station, and a uniquely talented painter. But of his many career achievements, few are as important as the moment he saved the Apollo 12 Mission.

Alan Bean died on Saturday in Houston after battling an illness. NASA Administrator Jim Bridenstine released a statement mourning the loss of the 86-year-old former astronaut, highlighting his achievements and the 11 world records Bean shattered in the areas of space and astronautics.

“As all great explorers are, Alan was a boundary pusher,” Bridenstine said. “Rather than accepting the limits of technology, science, and even imagination, he sought to advance those lines — in all his life’s endeavors.”

Bean was the Lunar Module Pilot of Apollo 12, which made the second successful moon landing in 1969. During his 31 hours on the moon, Bean collected lunar samples and checked on the status of Surveyor 3, which had landed two years earlier. But Bean and his fellow astronauts, Commander Charles “Pete” Conrad, Jr. and Command Module Pilot Dick Gordon, almost didn’t make it.

From left to right: Pete Conrad, Dick Gordon, and Alan Bean pose with their Apollo 12 Saturn V moon rocket in the background on the pad at Cape Canaveral on 29 October 1969
From left to right: Pete Conrad, Dick Gordon, and Alan Bean pose with their Apollo 12 Saturn V moon rocket in the background on the pad at Cape Canaveral on 29 October 1969

Just seconds after the Saturn V rocket carrying the astronauts launched, the large booster was struck by lightning. Immediately, multiple instruments inside the Apollo Command Module went offline and the spacecraft began transmitting nonsensical data to the ground. The astronauts began to worry once they realized the lightning also decalibrated Gordon’s navigations platform. They were on a space mission without guidance.

“Okay, we just lost the platform, gang,” Conrad called down to Houston. “I don’t know what happened here; we had everything in the world drop out.”

Back in Houston, flight controller John Aaron deduced that switching the rocket’s Signal Conditioning Equipment (SCE) to its backup mode would bring it back online. He told flight director Gerry Griffin to convert the “SCE to Aux,” but Griffin didn’t recognize the command. Griffin passed the message to Conrad, but he didn’t recognize the command, either. The only person on the spacecraft to recognize the command was Bean, who found and flipped the appropriate switch to revert SCE to its backup mode.

Thanks to Bean’s fast move, Mission Control once again received the correct telemetry data to guide Apollo 12 on its mission. This near-tragedy turned into a triumphant win.

“I remember saying to myself, ‘You know, this is really the moon. We’re really here. That’s the Earth up there.’ And I said it two or three more times to myself,” Bean said in a 2016 interview with NPR.

Bean would go on to command the second Skylab mission in 1973, but would eventually give up space exploration for painting. “Even in this endeavor,” Bridenstine said, “his passion for space exploration dominated. We will remember him fondly as the great explorer who reached out to embrace the universe.”

Photos via Wikicommons, NASA