But the triumph was equally human. The flight controllers, led by Kranz, coined the phrase “tough and competent” as their new mantra. They rewrote the book on mission rules, contingency planning, and real-time problem-solving. The disaster forced NASA to redesign the entire service module, adding a third oxygen tank and a backup battery. It also instilled a culture of “stop and think” that would prove vital in later missions, including the Space Shuttle program.
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. Apollo 13
The cold was unbearable. To save power, they shut off all non-essential systems. The temperature inside the LM dropped to near freezing—about 38°F (3°C). Water condensed on every surface. The men developed urinary tract infections. Haise ran a fever of 104°F. They slept in shifts, shivering violently, their breath fogging the tiny windows. The Moon, once their destination, now became their slingshot. They looped around the far side at a distance of 254 kilometers (158 miles)—closer than any lunar module had ever come. During the 25 minutes of radio blackout behind the Moon, the crew was utterly alone. Lovell later wrote that he felt the silence “like a physical weight.” When they emerged, the critical burn to accelerate their return to Earth had to be performed with pinpoint accuracy. But the triumph was equally human
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. The disaster forced NASA to redesign the entire
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.
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.
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.”