John W. Aaron is a legendary former NASA engineer, and was a flight controller during the Apollo program. He is widely credited with saving the Apollo 12 mission when it was struck by lightning shortly after liftoff and played an important role during the Apollo 13 crisis, earning him the highly complimentary appellation of "a steely eyed missile man".
John Aaron was born in Wellington, Texas and grew up in rural Western Oklahoma near Vinson in Booger Hollow, one of the youngest in a family of eight children. His mother was a minister, and his father was a cattle rancher. After spending a year attending Bethany Nazarene College, he transferred to Southwestern Oklahoma State University, from which he graduated in 1964 with a BS degree in physics. Although he had intended to teach math and science after graduating from college, he applied for a job at NASA on the recommendation of a friend.
When he arrived at NASA, Aaron was trained as an EECOM, a flight controller with specific responsibility for the electrical, environmental and communications systems onboard the spacecraft. By January 19, 1965, when the unmanned Gemini 2 was launched, he was already working in Mission Control.
When Apollo 12 launched on November 14, 1969, John Aaron was on shift. Thirty-six seconds after liftoff, the spacecraft was struck by lightning, causing a power surge. Instruments began to malfunction, communications dropped out, and telemetry data became nonsensical. The flight director, Gerry Griffin, expected that he would have to abort the mission. However, Aaron realized that he had seen this odd pattern of telemetry before.
A year before the flight, Aaron had been observing a test at Kennedy Space Center when he had noticed some unusual telemetry readings. On his own initiative, he traced this anomaly back to the obscure Signal Conditioning Equipment (SCE) system, and became one of the few flight controllers who was familiar with the system and its operations. In the case that first drew his attention to the system, normal readings could have been restored by putting the SCE on its auxiliary setting, which meant that it would run even under low-voltage conditions.
Aaron surmised that this setting would also return the Apollo 12 telemetry to normal. When he made the recommendation, "Flight, try SCE to 'Aux'", most of his mission control colleagues had no idea what he was talking about. Both the flight director and the CapCom asked him to repeat the recommendation. Pete Conrad's response to the order was, "What the hell is that?" Fortunately Alan Bean was familiar with the location of the SCE switch inside the capsule, and flipped it to auxiliary. Telemetry was immediately restored, allowing the mission to continue. This call earned Aaron the lasting respect of his colleagues, who declared that he was a "steely-eyed missile man", the absolute highest of NASA compliments.
Aaron was off duty when the Apollo 13 explosion occurred, but was quickly called to Mission Control to assist in the rescue and recovery effort. Flight Director Gene Kranz put Aaron in charge of the Command Module's power supply. He was in charge of rationing the spacecraft's power during the return flight. He is also credited with developing the innovative power up sequence that allowed the Command Module to reenter safely while running on very limited battery power.
Going against existing NASA procedures, he ordered the instrumentation system to be turned on last, just before reentry, rather than first. The call was a calculated risk. Without the instrumentation system, the crew and controllers would not know for certain if the cold startup had been successful until the last possible moment before reentry. However without this sequence change, the capsule would have exhausted its battery supply before splashdown. The procedure was a success, and the crew was recovered safely.
After the Apollo program ended, Aaron remained at NASA. He worked on the Skylab program, and was involved in the development of the Space Shuttle software. Starting in 1984, he worked on the abortive Space Station Freedom project; he became manager of Johnson Space Center's space station projects office in 1989. Four years later, however, he was forced to resign from the position after Senator Robert Krueger blamed him for $500 million in overspending on the station project.
Aaron became a manager in Johnson Space Center's Engineering Directorate in 1993, and stayed in the directorate until he retired from NASA in 2000.
A character based on John Aaron was portrayed by actor Loren Dean in the 1995 film Apollo 13. Aaron was also played by John Travis in the 1998 mini-series From the Earth to the Moon. He was interviewed in the PBS documentary Apollo 13: To the Edge and Back, and in two History Channel documentaries about Mission Control, Failure Is Not an Option and Beyond the Moon: Failure Is Not an Option 2.