"Flight, EECOM. Try SCE to aux."
On November 14th, 1969, those six words saved Apollo 12.
36.5 seconds after lift-off, lightning struck the Saturn V rocket. Protective circuits kicked in, shutting down all three fuel cells. Nearly every warning light on the Command Module's control panel lit up. Its instrumentation malfunctioned. The telemetry the spacecraft sent back to Houston's Mission Control became garbled and useless.
Flight director Gerry Griffin was ready to abort the mission. But Aaron was in the room.
As the man in charge of the spacecraft's electrical, environmental, and communications systems (EECOM), 27-year-old Aaron had an encyclopedic knowledge of those systems, as well as an eidetic memory. At that critical moment, he recalled a simulation he had witnessed at Kennedy Space Center a year before. He had noticed unusual telemetry readings and, on his initiative, traced the anomaly back to the obscure Signal Conditioning Electronics (SCE) system. He had determined that switching the SCE to its auxiliary setting would reset the instrumentation and restore accurate readings.
The SCE was so arcane that Aaron was the only flight controller on duty that day familiar with it. When he suggested that the astronauts in the capsule switch the SCE to auxiliary, neither Flight Director Griffin, CAPCOM (capsule communicator) Gerald Carr nor Mission Commander Pete Conrad knew what Aaron was talking about. But Lunar Module Pilot Alan Bean remembered the location of the SCE switch inside the capsule from a training incident a year earlier.
Bean flipped the switch to aux. The action immediately restored telemetry and saved the mission.
John grew up in the sticks. A "very rural community," he called it. There were but nine people in his Vinson, Oklahoma high school graduating class. His mother was a minister, his father, a cattle rancher.
John wanted to teach, but only to make enough money to get into his dream profession: raising cattle. He entered college seeking degrees in physics and math, intending to teach those subjects until he had saved enough to establish a herd of Herefords.
Once in college, he became enamored with physics and math, and neglected to take the education courses he needed to obtain a teaching degree.
John would have to go to school an extra year to complete the courses he required. He wasn't looking forward to that.
April 13th, 1970. Apollo 13 was on its way to the moon. Aaron, still EECOM Manager, was off-shift, at home, shaving. The phone rang.
There had been an explosion. Apollo 13's Command Module was crippled. The spacecraft could no longer generate electricity. The only power sources remaining were a few batteries. Landing on the moon was out of the question. The new mission objective: get the three astronauts, Jim Lovell, Fred Haise, and Jack Swigert, back home safely.
Mission Control had shut the Command Module down. The astronauts had moved to the cramped Lunar Module, which had become a makeshift lifeboat. They had successfully established a "free-return trajectory" and were on their way back home. To survive the fiery re-entry through the Earth's atmosphere, they would need the protection of the Command Module's heat shield. They were going to have to get back into the Command Module and power it back up. The Command Module had never been shut down during flight before. It had never been powered up during flight, either.
Would it power up at all? Even if it did, the power left in the batteries seemed nowhere near what was necessary to run even just the essential systems. The power would undoubtedly run out way before the spacecraft reached Earth. Lovell, Haise, and Swigert were doomed.
Flight Director Gene Kranz made a critical decision. He made one man and one man only, responsible for the mission's power supply. Aaron.
Aaron realized that the sequence in which the astronauts powered up the systems would have a massive impact on the amount of power used. He devised an innovative power-up procedure that would turn on the instrumentation system, which included telemetry and communication, last. This sequence ran contrary to accepted methods. Without instrumentation, the crew and flight controllers would not know if the cold startup had been successful until the last possible moment before re-entry. Furthermore, the astronauts in charge of executing the sequence were cold, hungry, thirsty, and sleep-deprived, making a complicated process even more fraught. But Aaron determined that powering up in any other order would result in the capsule exhausting its battery supply way before splashdown. Although quite risky, this sequence was, really, the only choice.
The procedure was a success. The crew made it home safely. Once again, Aaron saved the day.
Just as John was reluctantly resigning himself to another year of college, Richard Bates, a friend of John's who had graduated a year before, told John that NASA was hiring people to work on the space program. John knew nothing about NASA or the space program, but at Bates's suggestion, he submitted a Form 57, NASA's employment application. He thought he might get an interview.
Instead, he received a telegram from Mona Kazmierski of NASA's human resources department. The telegram constituted a job offer. The job paid $6,770 per year, more money than John had ever seen. He recalls:
Well, you know, I'm broke. I'll go down there and do that a couple of years, and then I'll come back and raise Herefords.
That was my plan.
Fortunately, things didn't go according to plan.
John Aaron was born in Wellington, Texas, and grew up near Vinson, Oklahoma. He spent a year at Bethany Nazarene College, then transferred to Southwestern Oklahoma State University, where he graduated in 1964 with a B.S. in Physics. Later that year, John Aaron arrived at NASA and was immediately trained as an EECOM. He retired from NASA in 2000.
He neither taught, nor raised cattle.
Instead, he became, as his NASA colleagues dubbed him, a "steely-eyed missile man."
Attribution Note: In addition to the articles linked above, background information for this essay was gathered from the following Wikipedia articles: Apollo 12 and Apollo 13. I also consulted this NASA document, this NASA fandom page and this NASA Oral History Project interview transcript.
This essay was inspired by the fantastic podcast, 13 Minutes to the Moon. Season 1 describes the descent of Apollo 11's Lunar Module to the surface of the moon, and Season 2 recreates the entire Apollo 13 mission through interviews with the mission's actual astronauts (except for Jack Swigert, who died in 1982) and mission controllers. 13 Minutes to the Moon is an original podcast from the BBC World Service. But you should really listen to Kevin Fong say that.