13 — Apollo

Fate intervened just days before launch. Mattingly was exposed to German measles (rubella) via a friend, and while he showed no symptoms, NASA’s strict quarantine protocols demanded he be removed from the crew to protect the others. In a decision that would later seem prophetic, Mattingly was replaced by his backup, John L. “Jack” Swigert Jr. Swigert was a capable pilot, but he had only 48 hours to integrate into a tightly-knit team. The chemistry was slightly off; Lovell later recalled a moment of tension when Swigert used the wrong pronoun, saying “my” flight plan instead of “our.” That minor friction would soon dissolve into a life-or-death partnership. The first two days of the mission were unremarkable. The crew performed a trans-lunar injection burn, slingshotting them toward the Moon. On the evening of April 13—ironically, the 13th—the crew had just completed a television broadcast, showing the American public a somewhat sleepy view inside the spacecraft. Lovell signed off with a casual, “This is the crew of Apollo 13. Good night.”

Lovell would often say, “Apollo 13 wasn’t a failure. It was a triumph of the human spirit.” In the end, the mission did not land on the Moon. But it landed something far more profound in the collective memory: a reminder that in the cold, dark, infinite vacuum of space, the most powerful engine of all is the human mind, working together, duct-taping a square peg into a round hole to bring three men home.

It was meant to be the third lunar landing. A routine “mountain expedition” to the Fra Mauro highlands, a geologically rich area named after a 15th-century Italian monk. For the astronauts—James Lovell, Fred Haise, and Ken Mattingly—it was the culmination of years of relentless training. For the American public, weary of Vietnam War headlines and the gradual normalization of spaceflight, Apollo 13 was almost mundane. The networks had even ceased live coverage of the launch. But at 9:07 PM EST on April 11, 1970, the massive Saturn V rocket lifted off from Kennedy Space Center, carrying with it a crew and a spacecraft that would never touch the Moon, but would instead etch itself into history as NASA’s most harrowing and brilliant “successful failure.” The Crew: Experience and the Cruelty of a Measles Exposure The crew dynamics were critical to the survival that followed. Commander James A. Lovell Jr. was a space veteran, having flown on Gemini 7, Gemini 12, and Apollo 8—the first mission to orbit the Moon. For Lovell, Apollo 13 was deeply personal; it was his chance to finally walk on the lunar surface. Command Module Pilot (CMP) Thomas K. “Ken” Mattingly was the meticulous, brilliant navigator and systems expert. Lunar Module Pilot (LMP) Fred W. Haise Jr. was a former Marine Corps pilot and a civilian test pilot, making his first spaceflight.

They then transferred back into the frozen, dead command module Odyssey . They had to power it up from scratch, a procedure that had never been fully practiced. The batteries had to last. At 12:07 PM EST on April 17, 1970, the command module separated from the lunar module Aquarius —the little ship that had saved their lives. They aimed for the Pacific Ocean near Samoa. Apollo 13

Gene Kranz, the legendary flight director, gathered his “White Team” in the Mission Control conference room. He famously didn’t pray; he made a list. The decision, made in a matter of minutes, was audacious: they would abandon the command module, power it down completely, and use the Lunar Module Aquarius as a “lifeboat.” Aquarius was designed to support two men for two days on the lunar surface. It now had to support three men for four days, traversing 200,000 miles of cold, radiation-soaked space. The ingenuity displayed over the next 86 hours remains a textbook example of engineering triage. Inside the LM, designed for a short hop on the Moon, the CO₂ levels began to rise perilously. The lithium hydroxide canisters that scrubbed carbon dioxide were square—designed for the command module. The LM’s system used round canisters. A mismatch meant death by asphyxiation. On the ground, engineers led by Ed Smylie threw together a makeshift adapter using only materials known to be onboard: a plastic bag, a cardboard cover from a flight manual, a roll of gray duct tape, and a suit hose. They radioed up the instructions. Astronaut Fred Haise, with the steady hands of a surgeon, assembled the “mailbox” in zero gravity. It worked.

The initial plan was a “free return” trajectory—the simple loop around the Moon that would bring them back to Earth. But this would take too long; the CO₂ would kill them. They needed a faster, shorter path. Using the LM’s descent engine (which was never designed for continuous burns of this duration), they performed a 30-second burn, then a second, critical 4-minute 23-second burn. The margin for error was razor-thin. A miscalculation would send them careening off into deep space or skipping off Earth’s atmosphere like a flat stone on a pond. Lovell later said, “We had to thread a needle from a quarter of a million miles away.” With just hours to go, the crew jettisoned the crippled service module. As it drifted away, they saw for the first time the full extent of the damage: an entire side panel blown out, wiring and conduits hanging like shredded muscle. Haise whistled. Swigert said simply, “That’s got the whole side blown out.”

Onboard, the crew felt a loud “bang” and a shudder that ran through the entire spacecraft. Warning lights exploded across the instrument panel. Swigert, his voice tight but professional, radioed the now-immortal words: “Okay, Houston, we’ve had a problem here.” (The 1995 film famously misquoted it as “Houston, we have a problem.”) Lovell quickly confirmed, “Houston, we’ve had a problem.” In Mission Control in Houston, the flight controllers initially dismissed the warning lights as a possible instrumentation glitch. But then the telemetry began to scream. Main Bus B voltage dropped to zero. Then Main Bus A followed. The fuel cells—the ship’s primary power source—began to fail one by one. The crew watched in disbelief as their primary supply of oxygen bled into space. Within two hours, both oxygen tanks were completely empty. Fate intervened just days before launch

Without oxygen, they had no electricity. Without electricity, they had no heat, no navigation computers, and—most critically—no water (fuel cells produced water as a byproduct). The command module, Odyssey , was dying. The lunar landing was not just canceled; the crew’s very survival was now measured in hours.

For the crew, life went on. Ken Mattingly, who had been grounded by the measles, later flew on Apollo 16 and walked on the Moon. Fred Haise was slated to command Apollo 18, but the final three missions were canceled. He never got his lunar walk. Jim Lovell never flew in space again, though he remained with NASA for years.

Inside the Apollo 13 service module, a routine procedure requested by Swigert—a “cryo stir” of the liquid oxygen tanks—sent a command to a small, damaged fan inside Oxygen Tank No. 2. The tank had a fatal flaw: Teflon insulation on its internal wires had been damaged during a pre-launch test months earlier at the Kennedy Space Center. When the fan was turned on, a short circuit ignited the Teflon. In the pure oxygen environment of the tank, the fire was instantaneous and explosive. The tank’s internal pressure skyrocketed from 900 psi to over 1,000 psi in a fraction of a second. The tank blew its dome off, tearing a hole in the adjacent Oxygen Tank No. 1 and shredding the service module’s aluminum panel. “Jack” Swigert Jr

Splashdown occurred within one nautical mile of the recovery ship, the USS Iwo Jima. The astronauts were weak, dehydrated, and suffering from hypothermia and urinary infections. But they were alive. The Apollo 13 Review Board concluded that the explosion was caused by a combination of poor design, inadequate testing, and a series of minor errors that cascaded into a catastrophe. The Teflon-insulated wires in the oxygen tank, the use of an incorrect thermostat, and the decision to use 65-volt ground support equipment on a 28-volt system—all were human errors.

Then came the problem of navigation. Without the command module’s guidance computer, Lovell had to use the LM’s telescope to align the ship using the stars. But the explosion had left a debris field around the spacecraft, making star sightings impossible. The crew had to use the Sun’s terminator on Earth as a reference point. Lovell manually performed a burn that had never been simulated, using a wristwatch and a sextant.