The Apollo 13 spacecraft was set to be the third landing on the Moon. It turned in to a rescue mission, also known as the successful failure. The Apollo 13 mission appeared to be the smoothest flight of NASA’s Apollo programme so far for nearly 56 hours after it launched on April 11, 1970.
The spacecraft carrying astronauts Jim Lovell, Jack Swigert, and Fred Haise to their expected lunar landing had advanced nearly 200,000 miles from Earth and was nearing the moon’s orbit.
On April 13, just before 9 p.m., the crew finished a TV broadcast in which they gave a tour of the spacecraft and discussed how they were coping with weightlessness. “This is the crew of Apollo 13 wishing everybody a pleasant evening,” signed off Mission Commander Lovell, a captain in the United States Navy who had previously served on three missions (including Apollo 8).
Less than 10 minutes later, after a routine maintenance operation went wrong and caused the spacecraft’s oxygen tanks to explode, what was expected to be the third landing on the moon by the United States space programme turned into a desperate race to save the lives of three astronauts. Working around the clock from Mission Control at the Manned Spacecraft Center (now Johnson Space Center) in Houston, Texas, NASA flight controllers and engineers devised a series of novel techniques to safely return Lovell, Swigert, and Haise on April 17, capping off one of the most dramatic episodes in the history of the United States space programme.
Overlooked System Errors On The Apollo 13 Spacecraft
The Apollo spacecraft carried two tanks of liquid hydrogen and two tanks of liquid oxygen to power the fuel cells, which supplied the majority of the electricity used during the mission. The subsequent NASA inquiry found that the No. 2 oxygen tank onboard Apollo 13 was mistakenly dropped during repairs prior to the Apollo 10 mission in 1969, causing minimal internal damage that did not show up in subsequent inspections.
The reinstalled tank failed to completely empty itself of oxygen during testing in March 1970. The research team determined that heating the tank overnight would cause the liquid oxygen to burn off. The surge of power from the high-voltage DC system on the deck, however, caused the automatic shut-off switches on the tank’s heater to fail, causing the temperature to rise to over 1,000 degrees Fahrenheit. The heat apparently damaged the insulation on the wires inside the tank, essentially turning the tank into a bomb waiting to explode, despite the fact that there was no outward sign of the issue.
Explosion Caused By Chain Reaction
While in orbit, the astronauts had to regularly switch on the internal fans of the fuel tanks to stir the super cold oxygen, which appeared to stratify, or settle into layers. However, when Swigert switched on the fans on the second oxygen tank for a regular “cryo stir” on the night of April 13, the damaged wiring triggered a spark, which ignited the fire. The tank exploded at 9:08 p.m., when its internal pressure increased.
As Lovell recounts, the bang took both him and Haise off balance. “I looked up at Fred Haise, wondering if he knew what was causing the noise. And, based on his speech, he had no idea. Then I looked down at Jack Swigert in the command module, his eyes as wide as saucers. And I could see that…this was just the beginning of a long, perilous journey home.”
Swigert shouted, “Houston, we’ve got a problem here,” after seeing an alarm light switch on after hearing the bang of the exploded tank. (He was famously misquoted later.) More flashing lights soon signalled the loss of two of the ship’s three fuel cells, which provided potable water in addition to electricity for cooling the spacecraft’s systems and hydrating the astronauts.
Then, 13 minutes later, Lovell looked out the window and found something else troubling. “We’re venting something out into…space,” he reported. “It’s some kind of gas.” Since the two oxygen tanks were in the same section of the spacecraft, the explosion had also destroyed the other tank, causing it to leak oxygen into space.
Apollo 13’s Difficult Flight Back To Earth
Ground controllers in Houston have been activated to conduct an unparalleled survival operation. They directed the crew to exit the spacecraft’s command module, Odyssey, and enter the separate landing module, Aquarius. If all had gone according to plan, Aquarius would not have been enabled until the astronauts were ready to land on the moon. It now had to hold Lovell, Swigert, and Haise alive for an estimated 90 hours before they could move back to the damaged command module for reentry into the Earth’s atmosphere.
To save energy, the crew switched off all non-critical systems onboard the spacecraft and reduced their water intake significantly in order to have enough to cool the landing module’s overworked hardware. If so much carbon dioxide collected in Aquarius, Mission Control devised a plan for the astronauts to clear the gas out, instructing them to make a “letter box” out of plastic bags, cardboard, and tape in order to purge the gas using command module canisters.
“They devised a method and then word for word relayed it up to us,” Lovell tells HISTORY This Week. “Hose.” Time, duct tape, and an old sock were the only things that kept us alive.”
The Apollo 13 Mission Deemed a ‘Successful Failure.’
The crew prepared for the final stages of their journey to Earth by jettisoning the lunar module on April 17, after engineers in Houston successfully re-powered Odyssey. Finally, at 11:53 a.m., the Apollo 13 spacecraft re-entered the Earth’s atmosphere, landing in the Pacific Ocean near Samoa.
NASA graded the Apollo 13 mission as a “successful failure” because so much useful experience was gained during the rescue of Lovell, Swiger, and Haise. Beginning with Apollo 14, each spacecraft will be outfitted with an additional battery as well as a third reserve oxygen tank, located in a separate section of the service module from the other two, that could be used solely to supply air to the astronauts. No such incident occurred again over the next eight Apollo missions.