Apollo 12 was struck by lightning twice during launch and survived
Just 36 seconds after lifting off for the Moon in November 1969, Apollo 12's Saturn V rocket was struck by lightning, followed by a second strike 16 seconds later. The electrical surge tripped all three fuel cells, blinding the cockpit with warning lights and scrambling telemetry. The mission was saved when 26-year-old flight controller John Aaron recognized the obscure telemetry glitch and calmly radioed the fix: "Try SCE to AUX."
Lifting Off into the Storm
On the morning of November 14, 1969, Apollo 12 stood on Launch Complex 39A at Kennedy Space Center, prepared to become the second mission to land astronauts on the Moon. The crew consisted of Commander Charles "Pete" Conrad Jr., Command Module Pilot Richard F. Gordon Jr., and Lunar Module Pilot Alan L. Bean. Rain had moved over the Florida coastline, blanketing the pad in gray drizzle and low-hanging cloud decks. Among the thousands of spectators gathered to watch was President Richard Nixon, marking the first time a sitting United States president had traveled to Florida to observe a crewed space launch in person.
Launch rules at the time permitted liftoff during rain as long as surface winds and cloud ceiling limits were respected, and ground monitoring equipment showed no signs of active lightning activity in the immediate area. Because there were no active electrical discharges around the launch pad, flight directors gave the final clearance to proceed. At 11:22 a.m. Eastern Standard Time, the five giant F-1 engines of the Saturn V first stage ignited. Generating 7.5 million pounds of thrust, the 363-foot rocket cleared the launch tower and climbed directly into the dense, rain-soaked overcast.
The Rocket as a Lightning Rod
While observers on the ground had checked for ambient lightning, the launch vehicle itself fundamentally changed the electrical balance of the surrounding air. As a massive rocket climbs, it produces a towering plume of hot, ionized exhaust gas. This exhaust trail is composed of highly conductive ions and water vapor, effectively forming an unbroken electrical wire extending thousands of feet from the rocket engines back toward the ground. When the vehicle penetrated clouds containing strong static electric fields, it did not merely encounter existing lightning; it actively triggered it.
Exactly 36.5 seconds into the flight, at an altitude of approximately 6,000 feet, the first discharge occurred. The electrical current struck the rocket, traveled down its metal skin, and discharged down the ionized exhaust column directly into the mobile launcher at the pad. Spectators on the ground watched a brilliant bolt of electricity illuminate the clouds, tracing the rocket's ascent path. Sixteen seconds later, at 52 seconds after liftoff, a second lightning strike hit the climbing vehicle. Inside the spacecraft, the crew had no clear visual view of the strikes, but their cockpit panels immediately registered catastrophic disruption.
Chaos in the Cockpit
The first strike delivered an intense electrical transient throughout the Command Module Yankee Clipper. The massive electrical surge tripped the circuit breakers connecting the spacecraft's three hydrogen-oxygen fuel cells to the main direct-current buses. With the fuel cells suddenly severed from the system, the Command Module's electrical grid collapsed onto its internal chemical entry batteries. These batteries were intended exclusively for the brief duration of atmospheric reentry and were not sized to supply power for an entire lunar mission.
Inside the cabin, the master alarm blared, and the main display console lit up with dozens of warning indicators, including critical bus undervoltage lights. AC inverters tripped off the line, cutting power to basic cockpit instrumentation. The second strike at 52 seconds knocked out the gyroscopic Flight Director Attitude Indicator—colloquially known as the 8-ball—sending it tumbling aimlessly. Conrad later noted that he had never seen so many warning lights lit simultaneously in any ground simulation. Yet amidst the cockpit chaos, the crew continued to feel the steady, crushing acceleration of the Saturn V. The rocket's primary navigation system, the Instrument Unit mounted in a separate ring atop the S-IVB third stage, was completely independent of the Command Module's electrical architecture and continued to steer the booster on its planned trajectory.
Pattern Recognition in Mission Control
In the Mission Control Center in Houston, telemetry displays suddenly disintegrated into meaningless noise. Data screens monitoring hundreds of spacecraft parameters—temperatures, pressures, fluid levels, and electrical currents—began displaying erratic patterns, scrambled symbols, and impossible readings. Flight Director Gerald Griffin and the flight control team were suddenly flying blind. Without reliable telemetry, controllers could neither diagnose the state of the spacecraft nor determine whether the vehicle was safe enough to continue toward orbit or required an immediate in-flight abort.
At the Electrical, Environmental, and Consumables Operations (EECOM) console sat twenty-six-year-old John Aaron. Studying the wall of garbled data, Aaron experienced a moment of intense pattern recognition. Roughly a year earlier, during pre-flight ground testing at Kennedy Space Center, he had witnessed an identical, bizarre telemetry glitch when an unexpected power drop occurred in the spacecraft's Signal Conditioning Equipment (SCE). The SCE was the electronic box responsible for taking analog signals from spacecraft sensors and conditioning them into clean digital readouts for cockpit displays and ground radio links. Aaron realized that a transient voltage drop had knocked the SCE power supply offline, and the system could not recover on its default circuit.
Flipping the Switch
Trusting his recollection of the obscure ground test, Aaron pressed his headset button and calmly called over the loop: "Flight, EECOM. Try SCE to AUX." Griffin, having never heard the command in flight operations, asked him to repeat it. Aaron confirmed the directive, and Capsule Communicator Gerald Carr relayed the instruction directly to the crew: "Apollo 12, Houston. Try SCE to AUX." Inside the vibrating cabin, Conrad responded with genuine confusion, asking: "SCE to AUX? What the hell is that?"
Sitting in the right-hand couch as Lunar Module Pilot, Alan Bean was intimately familiar with the spacecraft's secondary systems and auxiliary panels. Bean instantly recalled the switch location on panel 3, located on the center instrument panel right in front of his position. He reached out and flipped the toggle switch from NORMAL to AUX, rerouting the Signal Conditioning Equipment to an auxiliary power bus. Telemetry screens in Houston snapped back to life instantly, restoring clean data streams to Mission Control. With instrumentation restored, the crew was able to reset the fuel cells by recycling their circuit breakers once the vehicle reached Earth parking orbit.
The Parachute Gamble and Lasting Rules
Although the spacecraft achieved orbit and the electrical buses returned to normal operation, mission managers faced a quiet, unresolved crisis. The electrical current from the lightning strikes had traveled across the Command Module's exterior hull, directly adjacent to the pyrotechnic charges used to deploy the spacecraft's drogue and main parachutes. Flight controllers harbored deep concern that the surge might have inadvertently fired or damaged the ordnance circuits. If the parachute mortars were disabled, the crew would survive the journey to the Moon only to perish during reentry into Earth's atmosphere.
Because there was no way to physically inspect or test the parachute pyrotechnics in space, NASA leadership concluded that aborting the mission offered no safety benefit over continuing it; the parachutes would either work or fail regardless of whether the mission completed its lunar objectives. Apollo 12 proceeded to the Ocean of Storms, executed a successful lunar landing, and returned safely, with all three main parachutes deploying without incident over the Pacific Ocean. The incident prompted NASA to establish strict weather launch commit criteria. Future launches were strictly barred from flying through or near cumulus clouds with high electrical charge potential, ensuring that rockets would never again act as lightning rods for their own destruction.
Key takeaways
•Apollo 12 did not simply get hit by bad weather; the rocket's conductive, ionized exhaust plume acted as a giant lightning rod, triggering the electrical discharge from charged clouds.
•The lightning strikes knocked all three fuel cells offline, forcing the Command Module to run on its temporary reentry batteries while scrambling telemetry sent to Houston.
•Twenty-six-year-old flight controller John Aaron saved the mission by recognizing the scrambled telemetry signature from a past test and calling out the obscure fix: switching the Signal Conditioning Equipment (SCE) to auxiliary power.
•The near-disaster forced NASA to adopt strict new launch commit criteria regarding electrified clouds and cumulus formations to prevent rockets from triggering lightning strikes in future missions.