The crew of Apollo 13 had survived some type of explosion which resulted in lost power capabilities and loss of oxygen. With the help of experts on Earth, they had moved aboard the Lunar Module, corrected their trajectory, survived the cold and a buildup of CO2, and shortened the trip home. Now, they had a few more hurdles to overcome before they could see their families again.
A Simple Procedure Complicated
Their new re-entry procedure required two more course corrections. One would align the spacecraft more towards the center of the re-entry corridor, while the other would fine tune the angle of entry. This angle had to be between 5.5 and 7.5 degrees. Too shallow and they would skip across the atmosphere and back into space, like a pebble skimmed across a lake. Too steep, and they would burn up on re-entry.
They could not afford to power up the guidance platform again and burn up their precious remaining power. They would have to determine the attitude of the ship manually. For experienced pilots, this would normally not be an impossible job, it would just be a matter of taking star sights. The problem now, though, came from the cause of their troubles. Ever since the initial explosion, the craft had been surrounded by a cloud of debris, glittering in the sun, and preventing such a sighting. The ground opted to use a technique worked out during Apollo 8, in which the Earth’s terminator and the sun would be used.
"Because it was a manual burn, we had a three-man operation. Jack would take care of the time," according to Lovell. "He'd tell us when to light off the engine and when to stop it. Fred handled the pitch maneuver and I handled the roll maneuver and pushed the buttons to start and stop the engine." The engine burn was successful, correcting their re-entry angle to 6.49 degrees.
A Real Mess
Four and a half hours prior to re-entry, the Apollo 13 crew jettisoned the damaged Service Module. As it slowly receded from their view, they were able to make out some of the damage. They relayed to Houston what they saw. "And there's one whole side of that spacecraft missin'. A whole panel has blown out. Almost from the base to the engine. Its really a mess."
Later investigaion said the cause of the explosion was exposed electrical wiring. When Jack Swigert flipped the switch to stir the cryo tanks, the power fans were turned on within the tank. The exposed fan wires shorted and the teflon insulation caught fire. This fire spread along the wires to the electrical conduit in the side of the tank, which weakened and ruptured under the nominal 1000 psi pressure within the tank, causing the no. 2 oxygen tank to explode. This damaged the no. 1 tank and parts of the interior of the service module and blew off the bay no. 4 cover.
Two and a half hours before re-entry, using a set of special power-up procedures relayed to them by Mission Control in Houston, the Apollo 13 crew brought the CM back to life. As the systems came back on, everyone aboard, in Mission Control, and around the world breathed a sigh of relief.
Spashdown
An hour later, their Lunar Module lifeboat was also jettisoned. Mission Control radioed, "Farewell, Aquarius, and we thank you." Jim Lovell later said of her, "She was a good ship."
The Apollo 13 Command Module, carrying its crew of Jim Lovell, Fred Haize, and Jack Swigert splashed down in the South Pacific on April 17 at 1:07PM (EST), 142 hours and 54 minutes after launch. It came down within sight of the recovery ship, the USS Iwo Jima, who had the crew aboard within 45 minutes.
The crew of Apollo 13 had returned to Earth safely, completing one of the most exciting adventures in the history of space exploration.
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