Apollo 13 was the seventh manned mission in the Apollo Space program (1961-1975) and was supposed to be the third lunar landing mission, but the three astronauts aboard never reached the moon. Instead the crew and ground control team scrambled through a hair-raising rescue mission. On April 13, 1970, an oxygen tank on board exploded. Ground control in Houston rushed to develop an emergency plan as millions around the world watched and the lives of three astronauts hung in the balance: commander James A. Lovell Jr., lunar module pilot Fred W. Haise Jr. and command module pilot John L. Swigert.

Apollo 13’s Mission

The Apollo 13 astronauts
T<em>he Apollo 13 lunar landing mission prime crew from left to right are: Commander, James A. Lovell, Jr., Command Module pilot, John L. Swigert Jr. and Lunar Module pilot, Fred W. Haise, Jr.</em>

On April 11, 1970, Apollo 13 launched from Cape Canaveral, Florida. On board were astronauts James Lovell, John “Jack” Swigert and Fred Haise. Their mission was to reach the Fra Mauro highlands of the moon and explore the Imbrium Basin, conducting geological experiments along the way.

WATCH: Apollo 13: Modern Marvels on HISTORY Vault 

"Houston, we've had a problem..."

At 9:00 p.m. EST on April 13, Apollo 13 was over 200,000 miles from Earth. The crew had just completed a television broadcast and was inspecting Aquarius, the Landing Module (LM). The next day, Apollo 13 was to enter the moon’s orbit. Lovell and Haise were set to become the fifth and sixth men to walk on the moon.

It was not to be. At 9:08 p.m.—about 56 hours into the flight—an explosion rocked the spacecraft. Oxygen tank No. 2 had blown up, disabling the regular supply of oxygen, electricity, light and water. Lovell reported to mission control: “Houston, we’ve had a problem here.” The Command Module (CM) was leaking oxygen and rapidly losing fuel cells. The moon landing mission was aborted.

LISTEN ON APPLE PODCASTS: 'Houston, We've Had a Problem'

How the Crew of Apollo 13 Survived

One hour after the explosion, mission control instructed the crew to move to the LM, which had sufficient oxygen, and use it as a lifeboat. The LM was only designed to transport astronauts from the orbiting CM to the moon’s surface and back again; its power supply was meant to support two people for 45 hours. If the crew of Apollo 13 were to make it back to Earth alive, the LM would have to support three men for at least 90 hours and successfully navigate more than 200,000 miles of space.

Conditions on board the LM were challenging. The crew went on one-fifth water rations and endured cabin temperatures a few degrees above freezing to conserve energy. The square lithium hydroxide canisters from the CM were not compatible with the round openings in the LM environmental system, meaning the removal of carbon dioxide became a problem. Mission control built an impromptu adapter out of materials known to be onboard, and the crew successfully copied their model.

Navigation was also extremely complicated; the LM had a more rudimentary navigational system, and the astronauts and mission control had to work out by hand the changes in propulsion and direction needed to take the spacecraft home.

On April 14, Apollo 13 swung around the moon. Swigert and Haise took pictures and Lovell talked with mission control about the most difficult maneuver, a five-minute engine burn that would give the LM enough speed to return home before its energy ran out. Two hours after rounding the far side of the moon, the crew, using the sun as an alignment point, fired the LM’s small descent engine. The procedure was a success; Apollo 13 was on its way home.

READ MORE: What Went Wrong on Apollo 13?

The Farthest Distance From Earth Reached by Humans

On April 15, 1970, Apollo 13 was 254 km (158 miles) from the lunar surface on the far side of the moon—and 400,171 km (248,655 miles) above the Earth’s surface, meaning the crew of Apollo 13 set a Guinness World Record for the farthest distance from Earth reached by humans.

Apollo 13 Crew Returns to Earth

Lovell, Haise and Swigert huddled in the chilly lunar module for three long days. In these dismal conditions, Haise caught the flu. On April 17, a last-minute navigational correction was made using Earth as an alignment guide. Then the re-pressurized CM was successfully powered up. One hour before re-entry into Earth’s atmosphere, the LM was disengaged from the CM.

Just before 1 p.m. on April 17, 1970, the spacecraft reentered Earth’s atmosphere. Mission control feared that the CM’s heat shields were damaged in the accident and waited a harrowing four minutes without radio communication from the crew. Then, Apollo 13‘s parachutes were spotted. All three astronauts splashed down safely into the Pacific Ocean.

Apollo 13 Voyage
Bettmann Archive/Getty Images
Apollo 13's mission path.

Apollo 13 Movie

Though Apollo 13 did not land on the moon, the heroism of the crew and the quick-thinking of mission control were celebrated widely as a success story. It was even made into the 1995 movie Apollo 13 starring Tom Hanks, Ed Harris, Bill Paxton and Kevin Bacon.