An explosion in space
On April 13, 1970, 56 hours into a mission to land on the moon, the astronauts aboard the Apollo 13 spacecraft heard a loud bang. Indications on oxygen tank 2 immediately went to zero quantity and the astronauts reported seeing “a gas of some sort” vent into space as the level in oxygen tank 1, the only other oxygen tank in the Service Module, gradually drifted to zero over the next 130 minutes. The three astronauts aboard Apollo 13, mission commander Jim Lovell, Fred Haise, and Jack Swigert, were en route to the moon in a damaged spacecraft with little power and heat.
The situation looked grim, but in an impressive feat of ingenuity, teamwork and engineering, the astronauts landed safely back on earth April 17, 1970.
Few of us work in the space industry, but there are many valuable lessons that can be learned from studying incidents like the Apollo 13 mission. The crew would likely not have made it home without the countless hours of training that went into preparing for the mission, both of the astronauts and the people on the ground. The extensive contingency planning also played a huge role in how quickly NASA was able to react to the situation and make decisions. Every organization benefits from effective training and having clear, accurate contingency and emergency plans so it is worthwhile to learn more about the “successful failure” of the Apollo 13 to gain insight about how to improve today.
A Cause Map, a visual format for performing root cause analysis, can be created in order to intuitively lay out the numerous causes that contributed to the potential loss of the crew on Apollo 13. Creating the Cause Map helps organize the information and make the cause-and-effect relationships between the causes clear. To view an intermediate level Cause Map of Apollo 13, click here.
Getting the astronauts home
Safe return from a lunar landing was impossible after the Service Module was damaged, and the mission was aborted within minutes of the explosion. The goal became to simply try to get the astronauts home safely. In order to bring the crew home, NASA had to overcome many obstacles and do it quickly.
Crew moves to the Lunar Module
The Command/Service Module’s power was generated by fuel cells that combined hydrogen and oxygen into water. Once the oxygen supply was depleted, the fuel cells shut down, leaving only the limited-duration battery for power.
Using the Lunar Module as a “lifeboat” had been talked about during a training simulation, but it wasn’t considered a likely scenario. Despite not being part of the original mission plan, the crew was able to shut down the Command Module completely and moved into the Lunar module to save the remaining power in the Command Module for re-entry.
Limited consumables in Lunar Module
The Lunar Module was intended to sustain 2 people for 1.5 days and it needed to support three people for approximately 4 days. The main concern was the limited water supply that was needed for drinking water and to cool equipment. Drinking water was restricted to 6 ounces each per day and astronauts drank fruit juices and ate wet-pack food when they ate. In order to stretch power supplies, the power was turned down to the lowest levels possible and the temperatures inside the Lunar Module dropped as low as 4 degrees C.
The supply of lithium hydroxide canisters needed to reduce carbon dioxide in the Lunar Module was also an issue. The Command Module had an adequate supply of canister, but they were not compatible with Lunar Module systems. Engineers on the ground improvised a way to join the cube-shaped Command Module canisters to the Lunar Module's cylindrical canister-sockets by drawing air through them with a suit return hose so that the Command Module canisters could be used.
Navigation also presented a signification challenge. Prior to the explosion, a normal mid-course correction had been done that put Apollo 13 on a course for a lunar landing and the course needed to be changed to put the spacecraft on a free-return to earth course.
The Lunar Module navigation wasn’t designed to be used in anything like this scenario. The debris from the explosion made it impossible to sight real stars. A new procedure using the sun as an alignment star had to be quickly created.
Restarting the Command Module
A complete power-up of the Command Module had to be done in-flight because it had been powered down after the explosion, something that had never been done or intended. A new procedure had to be quickly and accurately created.
The challenges listed above are by no means an exclusive list of the issues that had to be overcome to bring the Apollo 13 astronauts home. Brand new procedures were written in three pressure filled days instead of the normal three months. The astronauts were asked to perform brand new tasks under stress in a difficult environment. In my mind, getting the Apollo 13 crew home safely was every bit as impressive a feat as bringing a man home after he walked on the moon.
If you would like to learn more about what caused the explosion onboard Apollo 13 or more details about the mission, NASA has information on their website here.