" " Apollo 13 flight directors applaud the successful splashdown of the Command Module "Odyssey" after the spacecraft suffered an explosion that shut down almost every system necessary to sustain life onboard. NASA

Apollo 13 was headed for the moon. On April 11, 1970, the spacecraft lifted off. Fifty-five hours and 55 minutes later, an explosion shut down almost every system necessary to sustain life onboard.

The string of events leading to the explosion began in 1965, with an oversight involving the oxygen tank thermostats. Tank No. 2 — which had been damaged before the launch — violently ruptured when a fan was turned on. That set the stage for one of the most amazing collaborative rescues in history. So many things went wrong on Apollo 13, it's an engineering miracle that the crew — astronauts James Lovell, John Swigert and Fred Hayes — made it home at all, let alone alive and well [source: Banke].



Minutes after the crew completed a television broadcast from space, telling America everything was going well, an explosion shook the spacecraft. One disaster led to another. When Tank No. 2 blew up, the force caused another oxygen tank to malfunction. Immediately after, two of the craft's three fuel cells shut down. Apollo 13 was 200,000 miles (321,868 kilometers) away from home, venting oxygen into space, and its normal supply of electric power, water, oxygen, heat and light had been cut off.

The ingenuity that followed is a testament to the genius of the human mind and spirit. To conserve whatever power, food, water and oxygen was left, the astronauts aboard Apollo 13 survived on almost no food, water and sleep and in temperatures that dropped to near freezing. The crew members lost a combined 31.5 pounds (14.3 kilograms) in less than six days.

Meanwhile, the people on duty at NASA's Mission Control center from April 11 through April 17 found a way to get the men home. They did months of calculation in days. They found a way to get the lunar module to support the crew and get the spacecraft back to Earth, although it was never intended for that purpose. The canisters that removed carbon dioxide from the command module didn't fit the system in the lunar module. So Mission Control found a way for the astronauts to make them fit using tools they had onboard: cardboard, plastic bags and tape.

Still, with no controls, no extended life support and no navigation system, the biggest problem of all was how to get the craft into a trajectory for an Earth landing. Apollo 13 had already made the planned adjustments for a moon landing before the initial explosion.

Mission control developed a plan. The onboard navigation was based on finding a key star. That system was out. In three hours, NASA found a way to use the sun instead, a series of calculations that would normally take three months; and they found a way to use the moon's pull to get the craft into the right position, because they had to save all of the power for the trip home.

The calculations based on the sun turned out to be accurate to within less than 1 degree. Apollo 13 rounded the moon and descended toward Earth. So much condensation had built up on the walls of the lunar module from the days of cold that when the spacecraft finally powered up -- and heated up -- for the trip home, it rained inside the cabin [source: NASA].

Apollo 13 landed successfully on April 17, 1970, in the Pacific Ocean. While all of the astronauts were fine, the spacecraft, of course, was not. But that was typical for the time. NASA didn't have a working reusable spacecraft until 1981, when the first space shuttle, named Columbia, made history.