Apollo 13 (1970): The Successful Failure in Space

Apollo 13 was the third American mission intended to land astronauts on the Moon, and it became the most famous rescue in the history of spaceflight. Launched on 11 April 1970, it was crippled two days later when an oxygen tank exploded more than 300,000 kilometres (about 200,000 miles) from Earth. Through improvisation by the crew and engineers on the ground, astronauts Jim Lovell, Jack Swigert and Fred Haise looped around the Moon and returned safely on 17 April, earning the mission the nickname “a successful failure”.

Background

Less than a year earlier, Apollo 11 had achieved the first Moon landing in July 1969, and Apollo 12 followed in November. Apollo 13 was to land in the Fra Mauro highlands, a hilly region thought to contain material thrown out by the impact that formed the huge Imbrium basin. Studying it would help scientists date the Moon’s history.

The spacecraft had two crewed vehicles. The command module, named Odyssey, was attached to a service module that carried the main engine, oxygen tanks and fuel cells for power. The lunar module, Aquarius, was to carry two astronauts down to the surface while the third stayed in orbit.

The commander, Jim Lovell, was the most experienced astronaut of the time. He had flown on Gemini 7, Gemini 12 and Apollo 8, the first crewed flight around the Moon. Fred Haise, a former test pilot, was the lunar module pilot on his first spaceflight.

The original command module pilot was Ken Mattingly. A few days before launch, a member of the backup crew, Charlie Duke, came down with German measles (rubella). Mattingly had never had the disease and was judged at risk, so three days before launch he was replaced by the backup pilot, Jack Swigert. Mattingly never fell ill and later flew on Apollo 16.

Launch and outbound flight

Apollo 13 lifted off from Kennedy Space Center at 2:13 p.m. Eastern time on 11 April 1970. During the climb, the centre engine of the Saturn V’s second stage shut down about two minutes early because of severe vibrations, a problem known as pogo. The other engines burned longer to compensate, and the spacecraft reached orbit safely.

The flight to the Moon was so routine at first that the American television networks did not carry the crew’s broadcast live on the evening of 13 April. In a new experiment, the spent third stage of the rocket was steered to crash into the Moon so that the seismometer left by Apollo 12 could record the impact.

The explosion

At about 9:08 p.m. Houston time on 13 April, nearly 56 hours into the flight, Mission Control asked Swigert to stir the service module’s cryogenic oxygen tanks, a routine task. Seconds later the crew heard a loud bang, and warning lights came on. Swigert reported “Houston, we’ve had a problem”, and Lovell repeated the words moments later.

Oxygen tank No. 2 had exploded, blowing off an outer panel of the service module and damaging tank No. 1. Within a couple of hours the command module’s oxygen supply and its three fuel cells, which made electricity and water, were failing. Lovell looked out of a window and saw gas venting into space.

In Mission Control in Houston, flight director Gene Kranz and his team worked to understand the problem. It soon became clear that the landing was off and that the crew’s survival was in question. The command module’s limited batteries had to be saved for re-entry, so the astronauts powered it down and moved into the lunar module.

Lifeboat to the Moon and back

Aquarius had been designed to support two men for about two days. Now it had to keep three alive for around four. Engineers drew up plans to ration power, water and oxygen, and the crew switched off almost every system that was not essential.

The spacecraft was already on a path that would carry it around the Moon. About five and a half hours after the explosion, the crew fired the lunar module’s descent engine to put Apollo 13 back on a free-return trajectory, a course that would naturally bring it back to Earth. On 14 April they swung behind the far side of the Moon, reaching what was then the greatest distance from Earth ever travelled by human beings. About two hours later they fired the descent engine again to shorten the journey home.

A new danger emerged: carbon dioxide from the crew’s breath was building up. The lunar module’s filters were nearly used up, and the command module’s spare lithium hydroxide canisters were square, while the lunar module’s sockets were round. Engineers in Houston devised an adapter from items on board, including plastic bags, cardboard, hoses and tape, and talked the crew through building it. The improvised “mailbox” brought carbon dioxide levels down. The episode became one of the best-known examples of engineers solving a life-or-death problem using only the materials the astronauts actually had with them.

Conditions were miserable. With little power for heating, the cabin temperature dropped to just a few degrees above freezing. Condensation formed on the walls and panels, raising fears of electrical short circuits when the command module was switched back on. Water was rationed, the astronauts slept little, and Haise developed a urinary tract infection.

Re-entry and splashdown

The crew had to restart the cold, unpowered command module for re-entry using its limited batteries. Engineers and astronauts, including Mattingly, worked in simulators to develop a power-up sequence that stayed within the tight electrical budget.

On 17 April the crew released the service module and saw for the first time the extent of the damage, with a whole side panel missing. They then left Aquarius and released it too. Odyssey re-entered the atmosphere, and after a tense radio blackout that lasted longer than expected, its parachutes appeared. The capsule splashed down in the South Pacific near Samoa at 1:07 p.m. Eastern time and the crew were recovered by the USS Iwo Jima.

The investigation

NASA set up the Apollo 13 Review Board, chaired by Edgar Cortright, director of the Langley Research Center. Its report in June 1970 traced the failure to a chain of earlier events. The oxygen tank had been dropped about 5 centimetres (2 inches) during factory handling in 1968. Before launch, it would not empty normally during a ground test, so its internal heaters were left on for hours to boil the oxygen off.

The heaters’ thermostat switches had been designed for the spacecraft’s 28-volt supply, but the ground equipment used 65 volts. The switches welded shut, and temperatures inside the tank rose far above design limits, damaging the Teflon insulation on internal wiring. In flight, when the fans were switched on, the damaged wires short-circuited and ignited the insulation in the pure-oxygen tank.

The board also noted that the problem had escaped detection because the unusual ground test was not recognised as a hazard, and that the records of the tank’s earlier drop had not raised concern. The tanks were redesigned and a third oxygen tank, with an extra battery, was added to later service modules. Apollo 14 flew to Fra Mauro in early 1971.

Myths and facts

The famous line “Houston, we have a problem” was never spoken. The crew said “we’ve had a problem”, and the present-tense version was popularised by the 1995 film Apollo 13, directed by Ron Howard.

The phrase “Failure is not an option” is also widely associated with the mission, but it was written for the film rather than recorded during the flight. Gene Kranz later used it as the title of his memoir.

Timeline

• 1970, April (days before launch): Ken Mattingly is replaced by Jack Swigert after exposure to German measles.
• 1970, 11 April: Apollo 13 launches from Kennedy Space Center.
• 1970, 13 April, about 9:08 p.m. Houston time: Oxygen tank No. 2 explodes.
• 1970, 14 April: A descent engine burn puts the spacecraft on a free-return path; the crew pass behind the Moon.
• 1970, 17 April: The crew jettison the service and lunar modules and splash down in the South Pacific.
• 1970, June: The Cortright review board reports on the cause of the accident.
• 1971, 31 January: Apollo 14 launches with redesigned oxygen tanks.

Legacy

Apollo 13 became a celebrated example of crisis management, teamwork and engineering ingenuity. President Richard Nixon awarded the Presidential Medal of Freedom to the three astronauts and to the mission operations team. The story reached a new audience through Lovell’s 1994 book Lost Moon, written with Jeffrey Kluger, and the 1995 film.

The accident also cut short public enthusiasm for lunar exploration. Budget pressures had already led NASA to cancel Apollo 20, and later in 1970 Apollos 18 and 19 were cancelled too. The programme ended with Apollo 17 in December 1972.

Why it matters

Apollo 13 showed both the dangers of spaceflight and the ability of well-trained people to solve problems under extreme pressure. The mission failed in its goal of landing on the Moon, but bringing the crew home alive became one of NASA’s proudest achievements and a lasting lesson in engineering safety.