What Really Happened In The Apollo 13 Disaster?

“Houston we’ve had a problem here.”

These were the infamous words radioed back to NASA from the Apollo 13 crew. The Apollo 13 was supposed to be NASA’s third moon landing mission.  It was supposed to be a moon landing success that instead turned into one of the worst spacecraft malfunctions right in the middle of the journey. The infamous 1995 movie takes inspiration from this notorious accident, but what makes this spaceflight malfunction get so much more limelight out of all the space flight accidents in the annals of history?

Astronauts of Apollo 13

apollo 13 crew

From Left to Right: Fred Haise, Jim Arthur Lovell and Jack Swigert (Photo Credit: NASA/Wikimedia Commons)

The Apollo 13 spacecraft launched on April 11, 1970, from the Kennedy Space Center in Florida. The crew was composed of a three-person team.

First was James Arthur Lovell Jr., more popularly referred to as Jim Lovell, the commander of the Apollo 13. He was first designated as a Naval Aviator on February 1, 1954. In 1962, when NASA was looking for a second group of Astronauts for the Gemini and Apollo programs, Lovell applied and was selected. However, another fun fact is that it was the second time he applied and got picked. Lovell was the backup commander of Apollo 11 and was scheduled to command Apollo 14. Instead, he and his crew swapped missions with the crew of the Apollo 13.

Next, we have Jack Swigert, an American test pilot, as well as a mechanical and aerospace engineer, United States Air Force pilot, and NASA astronaut. He was the Commander Module Pilot for the Apollo 13 mission. The funniest thing is that Jack was not even commissioned to fly on Apollo 13. However, when Ken Mattingly contracted the German measles (which supposedly never happened) three days before the launch, Jack was brought in as a last-minute replacement.

Finally, we have Fred Wallace Haise Jr., who was a former American fighter pilot with the U.S Marine Corps and a test pilot before joining NASA. He was inducted in the NASA Astronaut Group 5 in 1966. His role was to be the lunar module pilot aboard the Apollo 13 space mission.


Apollo line drawingThe spacecraft had three main modules, all of which had various responsibilities in their contribution towards the success of the mission.

The first is the Service Module, which was designed to provide consumables, such as oxygen, water, and power for the mission. It was also the primary propulsion area of the aircraft. It was in this module of the spacecraft where the first fault occurred. It was maintained until just after re-entry into orbit to prevent the heat shield of the command module from deteriorating, due to prolonged exposure to the cold of space.

Naturally, the next part of the spacecraft is the Command Module, which was equipped with couches, and served as the crew compartment and control center.  The main purpose of this module was to bring the astronauts safely back upon re-entry.

The final module was the Lunar Module, which was designed for landing on the moon and would serve as an operation base and living quarters for the astronauts. It played a critical role in the survival of the astronauts and acted somewhat like a lifeboat.

A Crucial Fault Occurs

The Apollo 13 mission is successfully dubbed as the ‘successful failure’ by NASA. The objective of the mission was to land on the moon, but 56 hours into the flight, there was a loss of cryogenic oxygen from the service module, and an electrical fault occurred.


Five words that defined the biggest real-life drama of space (Image Courtesy: Apollo 13, the movie)

The exact sequence of events occurred after 55:53:18 of ground elapsed time (GET). All spacecraft systems were in nominal condition until the fans in the cryogenic oxygen tank were turned on. After the fan was switched ON, a short circuit fault occurred at a fuel cell supplying power to the fan of the cryogenic oxygen tank in the service module. Following this, within a few seconds, two other short circuit faults were detected.

The electrical short circuit that had occurred in the fan of the cryogenic oxygen tank resulted in the melting of the wire insulation, resulting in an increase of pressure within the cryogenic oxygen tank. This lead to the pressure within the cryogenic oxygen tank reaching 1008 psi. Although a relief valve was present, this helped in reducing the pressure for only 9 seconds, after which the relief valve failed and closed, causing the pressure to rise again.

This led to several other faults occurring within a matter of seconds, including a tank line bursting open due to severe heat generated by the short-circuiting of the cryogenic oxygen tank.

The Survival

Severe heat buildup in the service module had led to the power failure. This led to the malfunction of all vital life-supporting functions. The power failure led the crew to evacuate the command module immediately. With only one alternative place to survive, the team shifted to the lunar module, which was intended to help them survive on the surface of the moon.

With careful coordination between ground control and the astronauts, they were able to devise an economic return plan, taking into consideration the shortage of amenities and fuel. The method they devised was to use the moon’s gravity as a gravitational slingshot.

Apollo 13 timeline

Trajectory plan from the ground station at Houston to Apollo 13

This was done by flying Apollo 13 close enough to the moon to get into its field of gravity, but not so close as to be pulled into it. Apollo 13 revolved around the moon and picked up momentum from the orbital velocity of the moon before shooting back home. The Apollo 13 astronauts remain the farthest that any human has gone into space, as they have orbited the dark side of the moon. At the right escape point, they turned on their boosters, which allowed them to slingshot out of the moon’s orbit and gave them a velocity, which propelled them towards Earth.

This truly is a remarkable feat, not only considering the age in which it was done, but also the level of nerves both the astronauts and ground control had to show. Also, considering the ingenuity of both parties at critical moments, this story is one that people will continue to tell for generations to come.


  1. Smithsonian National Air and Space Museum
  2. NASA.com
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About the Author:

Venkatesh is an Electrical and Electronics Engineer from SRM Institute of Science and Technology, India. He is deeply fascinated by Robotics and Artificial Intelligence. He is also a chess aficionado, He likes studying chess classics from the 1800 and 1900’s. He enjoys writing about science and technology as he finds the intricacies which come with each topic fascinating.

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