April 13, 1970: Apollo 13 Explodes


Apollo 13 was the 3rd crewed mission meant to land on the moon, and the 7th crewed mission in the Apollo space program. It was launched on April 11, 1970 from the Kennedy Space Center, but 2 days into the mission to the moon, it was aborted after an explosion. The crew looped around the moon, and everyone returned safely on April 17.

The explosion happened when a routine stir of an oxygen tank ignited. The explosion vented the contents of both oxygen tanks to space, leaving the crew without oxygen. The team on board and back at home worked to bring the crew home alive. The crew experienced a cold, wet cabin, a shortage of water, and limited power.

The aircraft ultimately splashed down into the South Pacific Ocean, and everyone on board lived.


On board Apollo 13 was commander Jim Lovell, command module pilot Jack Swigert, and lunar module pilot Fred Haise. In the morning of the 3rd day of the mission, on April 13, a TV broadcast was scheduled, where Lovell would act as the emcee and show the audience around the aircraft.

A little bit over 6 minutes into the broadcast, the pressure sensor in one of the oxygen tanks appeared to be malfunctioning, so Sy Liebergot, the person in charge of monitoring the electrical system from the ground, requested that the stirring fans in the tank be activated, a task typically done once daily. This would be an additional, unplanned stir, but would help make the pressure readings more accurate. Swigert activated the switches controlling the fans, and turned them off a few seconds later.

A touch over a minute and a half later, the team heard a large bang and began to see fluctuations in the power, and the firing of the attitude control thrusters. They lost contact with Earth for 1.8 seconds, and when it came back, Swigert famously reported: "Okay, Houston, we've had a problem here".

Initially, Lovell thought that the noise came from Haise activating the cabin-re-pressurization valve, which he sometimes did to startle his crew mates, but he became more concerned when he saw that Haise had no idea what was going on. Swigert's initial thought was that a meteoroid may have struck them, but there was no leak. The problem they identified, a Main Bus B undervolt, meant that they didn't have sufficient voltage flowing from the 3 power cells to the power distribution systems. Haise checked the status of the fuel cells, and found 2 were dead. Entering lunar orbit was forbidden if fuel cells weren't operational.

In the next minutes after the accident, more bizarre readings were being seen, including that tank 2 was empty, tank 1's pressure was falling, the computer was reset and the antenna was not working. Liegergot had missed the concerning signs from tank 2, as he was focused on tank 1. Lovell reported a "gas of some sort" venting into space. They realized they had a serious problem at hand.

Because the fuel cells need oxygen to operate, when Tank 1 ran dry, the rest of the fuel cell would shut down, so their only sources of power would be batteries and a surge tank. Typically used for the final hours of the mission, the fuel cell was already pulling oxygen from the surge tank to survive. At this point, the mission was just to get the crew home alive.

They had charged batteries and full oxygen tanks, initially planned for use on the surface of the moon, and the astronauts were directed to power up the lunar module for use as a "lifeboat". They were lucky the accident happened on the way there instead of on the return flights, because the lunar module would have already been used.

The initial plan was to conduct a "direct abort", where the crew would turn around and come home before reaching the moon. But, because the Service Propulsion System (SPS), the engine they would have used, may have been damaged in the accident, they decided on a longer route: they would loop around the moon, and then come back to Earth. They could do this through the Descent Propulsion System (DPS), though it wasn't as powerful as the SPS. Another problem: The DPS was never been planned to maneuver the spacecraft, so the software for Mission Control's computers would need to be written.

Lovell copied down the information and performed hand calculations to transfer to the guidance system, and Mission Control checked his figures. They anticipated getting Apollo 13 back in about 4 days, with a splashdown in the Indian Ocean. Jerry Bostick, along with other Flight Dynamics Officers (FIDOs), wanted the travel time to be shorter, and hoped for a splashdown in the Pacific Ocean, where recovery forces could better access them.

The FIDOs proposed various solutions. In one, they'd save 36 hours, but the aircraft's heat shield would be exposed to space, which it hadn't been designed for. They ultimately decided on a different plan: a burn using the DPS that would save 12 hours and lead to a land in the Pacific.

I can't tell you exactly what they did, but the burn went off as planned. Typically, alignment is easy to check, but because of all of the debris, it wasn't practical. The astronauts used the sun to give their position, and everything worked out, they were less than a foot per second off. They were headed back to Earth.

The trip back to Earth was not great. They had enough oxygen to sustain 2 astronauts for 45 hours on the moon, not enough for 3 astronauts during their journey home. They had a lot of other issues, but were able to work with the ground crew to improvise solutions.

The electricity was an issue as well, and water for equipment cooling and drinking was scarce. Power was reduced to the lowest level possible, and even with extreme rationing for the personal consumption of water, they calculated that they would run out of water for cooling equipment about 5 hours before reentry. They rationed to .2 liters of water per day, leading to a group 31lb weight loss and UTIs.

The spacecraft was dark, and the temperature was a miserable 38 degrees Fahrenheit. They would be too hot in their spacesuits, so they put on as many layers as they could find. Despite attempts to keep warm, they were extremely cold. Lovell and Haise wore their lunar EVA boots, but Swigert was not scheduled to walk on the moon so he didn't have any, and he had gotten his feet wet while filling water bags. When they went to the bathroom, they had to store it in bags and not discharge into space, as to not throw off trajectory. Despite the miserable conditions, the crew did not complain.

They drifted off course a bit while heading back to Earth, and had to do 2 more burns to get the trajectory back within safe limits. The crew was able to see all of the damage for the first time, and they photographed it. An entire panel was missing from the exterior, the fuel cells were tilted, the antenna was damaged, and debris was everywhere.

All problems had been solved, the only thing left was to splashdown. The crew was supposed to lose contact for 4 minutes, but ended up losing it for 6 minutes, leading the team on the ground to believe something had gone wrong. But, they regained contact, and safely splashed down in the Pacific Ocean, only 3.5 nautical miles away from the recovery ship. The crew was tired, but in good condition. They were flown to Hawaii where President Richard Nixon awarded them the Presidential Medal of Freedom, and then were flown back to Houston.


Lovell and Haise reflected on their journey with NASA's podcast, "Houston, We Have a Podcast" which is a pretty amazing name. (2)

Lovell credited positivity, and solving issues as they came up, with their ability to make it home safely. "You have to look at what you've got, and how you can get home. And as long as we could get over one crisis after another, we kept, you know, thinking positive, and until we finally made the landing," Lovell said. (2)

Lovell echos what most everyone has said about the explosion: If it had happened at any other time, they probably wouldn't have made it home, and could have ended up stranded on the moon. (2)

The biggest lesson that the crew took away from Apollo 13 was teamwork. Lovell said that he couldn't just close his eyes and hope for a miracle, because he had to work for the miracle, with everyone on board and helping at home. (2)

Jim Lovell retired from the space program in 1973 and went to work at the Bay-Houston Towing Company, going on to become CEO in 1975. He became president of Fisk Telephone Systems in 1977, and became executive VP of Centel, retiring in 1991. (3)

He wrote a book about the Apollo 13 mission, and the book was the basis for the Apollo 13 movie. Lovell had a cameo in the movie as the captain of the ship that rescued them after the splashdown. A small crater in the moon was named after him, among countless other awards and recognitions. (3)

Fred Haise continued with the space program and was the backup mission Commander for Apollo 16, and was slated to command Apollo 19, but it was cancelled due to budget cuts. He moved to the Space Shuttle Program and continued his success. In 1979, he left NASA to become a test pilot for Grumman Aerospace Corporation, and stayed there until retiring in 1996. He has been given many awards and honors for his work, and was inducted to the International Space Hall of Fame in 1983, the Aerospace Walk of Honor in 1995, and the U.S. Astronaut Hall of Fame in 1997. (4)

Jack Swigert stayed with NASA after Apollo 13 as the command module for the Apollo-Soyuz Test Project. Swigert got caught up in a scandal where Apollo astronauts made agreements with a stamp dealer in West Germany to autograph items in exchange for payment. When Swigert was found to be involved, he was removed from the mission. (5)

After NASA, he became the executive director of the Committee on Science and Astronautics, U.S. House of Representatives. He tried to get into a political career, but was defeated in his run for the U.S. Senate. He became the VP of B.D.M Corporation and left in 1981 to become VP of financial and corporate affairs for International Gold and Minerals Limited. He ran for U.S. Congress in 1982 and won the seat with 64% of the popular vote. Unfortunately, during his run, he was diagnosed with a malignant tumor and bone marrow cancer, and he died at age 51, 7 days before he would have started his congressional term. He was also remembered and given various awards for his achievements. (5)

This is one of the rare stories I wrote where nobody died because of the disaster, and through brilliant innovation and teamwork, everyone was brought home alive. Apollo 13 has been well-memorialized, the movie being one of the most famous space movies, and the brilliant men on board and on the ground deserve the legacy they achieved.


1. https://en.wikipedia.org/wiki/Apollo_13#Accident

2. https://www.cnn.com/2020/04/13/us/apollo-13-explosion-anniversary-scn/index.html

3. https://en.wikipedia.org/wiki/Jim_Lovell

4. https://en.wikipedia.org/wiki/Fred_Haise

5. https://en.wikipedia.org/wiki/Jack_Swigert

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