... was the seventh manned mission in the Apollo programme, and was intended to be the third to land on the Moon. It was launched at 19:13:00 UTC (GMT) on 11 April 1970 – 14:13 local time. The mission commander was James A. Lovell; his crew consisted of John L. 'Jack' Swigert (Command Module Pilot) and Fred W. Haise (Lunar Module Pilot). Lovell was the world's most experienced astronaut, on his fourth space mission; for both Swigert and Haise, this was their first mission. Swigert was a late replacement for Ken Mattingly, who was grounded by the flight surgeon after exposure to German measles.
Just under 56 hours into the mission, with the craft 205,000 miles from Earth (about 80% of the way to the Moon), mission controller Sy Liebergot noticed a low–pressure warning signal on a hydrogen tank in the command module. This could have meant a problem, or it could have indicated that the hydrogen just needed to be resettled by heating and fanning the gas inside the tank. This routine procedure was called a 'cryo stir,' and was supposed to stop the supercold hydrogen from settling into layers.
Two minutes after Swigert threw a switch to start the cryo stir, the crew heard a "loud bang" and noticed that one of the command module's two main electrical circuits had experienced a drop in power ("a main B bus undervolt" in the words of mission commander James Lovell). They notified Mission Control – Swigert famously reporting, "Houston, we've had a problem here." (Ron Howard's film Apollo 13 took some creative licence, changing the words and having them said by Lovell – played by Tom Hanks.)
Much later, a NASA investigation determined that some wires had been exposed in the oxygen tank, through a combination of manufacturing and testing errors before the flight. That night, a spark from one of them caused a fire, ripping apart one oxygen tank and damaging another inside the spacecraft.
Since the command module's fuel cells were powered by oxygen, power was reduced as well. The spacecraft attempted to stabilize itself by firing small jets, but this didn't work very well as several of the jets had been slammed shut by the explosion.
The damage to the service module made safe return from a lunar landing impossible, so Lead Flight Director Gene Kranz ordered an abort of the mission. The existing abort plans, first drawn up in 1966, were evaluated; Kranz chose the option to make one pass behind the Moon, and use the Moon's gravity to return the ship to Earth.
Luckily for Apollo 13, the damaged command module had a healthy backup: the lunar module, whose systems weren't supposed to be turned on until the crew was about to land on the moon. It didn't have a heat shield to enable it to survive the trip back to Earth, but it could keep the crew alive long enough to get there. The astronauts could then return to the command module for the final stage of the trip home. It wouldn't be straightforward; the consumables in the lunar module were intended to sustain two people for a day and a half, not three people for four days.
Haise and Lovell frantically worked to boot the lunar module up in less time than designed, while Swigert stayed in the command module to shut down its systems to preserve power for splashdown.
The crew performed a crucial burn to point the spacecraft back towards Earth, then powered down every non–essential system in the spacecraft. Without a source of heat, cabin temperatures quickly dropped close to freezing. Some food became inedible. The crew also rationed water to make sure that the lunar module – operating for longer than it was designed – would have enough liquid to cool its hardware down. Needless to say, staff at Mission Control back on Earth were also working round the clock to support them.
It was a long few days back home. The crew lost a total of 31.5 pounds in weight, and Haise developed a kidney infection. In the hours before splashdown, the exhausted crew powered up the command module (which had essentially been in cold storage for days, and could have shorted out if they were unlucky). They then prepared for splashdown, hoping against hope that the explosion hadn't damaged the heat shield.
Lovell, Haise and Swigert splashed down safely in the Pacific Ocean at 18:07:41 UTC on April 17 – just 1 hour, 5 minutes and 19 seconds short of six days after take–off. They were picked up by USS Iwo Jima 45 minutes later. The spacecraft design was revised, with better wires and an extra tank, and the problem didn't recur in subsequent missions. Although NASA's reputation was not enhanced by Apollo 13's design problems, the rescue of the mission was seen as a shining example of how NASA successfully solved a potential disaster in space.
The most detailed account I have found, while still remaining readable, is here, on the NASA website.
Apollo 13 is said to have travelled further from Earth than any other manned mission because on its pass behind the moon, it didn't make a burn to drop into lunar orbit. This meant that it passed higher above the far side of the moon than any other mission. But its record orbit height was only 254 kilometres (157 miles); what nobody seems to mention is how far the Moon was from the Earth at the time. As the Moon's orbital radius varies from 356,400 kilometres (221,500 miles) to 406,700 kilometres (252,700 miles), the variation in orbit height would seem to be insignificant if the Moon was further from the Earth during any other Apollo mission than it was during Apollo 13.
But there is no shortage of sources to corroborate the assertion that Apollo 13 holds the record. So for quizzing purposes, it's clearly the one to go for.
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