The immortal words that have so often been repeated – these were the words came from the Apollo 13 spacecraft and nearly spelt disaster for the three crew members, John Swigert, Fred Haise and James Lovell.
There were problems for the Apollo 13 mission before it even launched though. With Apollo 11 landing on the moon, the space race was over and many Americans were questioning why more money was being spent sending another mission to the moon. The popularity of space launches was declining, after all, this was the seventh manned mission into space that the American Apollo space program had launched and was the third that was supposed to land on the moon.
The Crew
The original crew of the Apollo 13 was slated as Jim Lovell, Commander; Ken Mattingly, Command Module Pilot and Fred Haise, Lunar Module Pilot. However, just seven days before the launch, the back-up Lunar Module Pilot, Charlie Duke, caught rubella from one of his children. Both the primary and back-up crew had been exposed to the disease. Mattingly hadn’t had rubella as a child and wasn’t immune to the disease. The flight surgeon insisted that he be grounded due to the risk of infection and that Jack Swigert take his position.
Mattingly never contracted rubella, however he was part of the Apollo 16 crew that was the fifth Apollo mission to land on the moon.
The Command Module and Lunar Module
Ground tests of the lunar module showed that one of the supercritical helium tanks might be poorly insulated, so the flight plan had to be modified so that the Lunar Module pilot entered the Lunar Module three hours earlier than originally planned to get an onboard readout of the tank pressure.
The number 2 oxygen tank for Apollo 13 was originally installed as part of the Apollo 10, and had been damaged when it was removed. The tank was fixed, tested and installed on Apollo 13. It was tested again. The number 2 tank didn’t behave the way it was supposed to. There was excess oxygen left in the tank and the test director decided to “boil-off” the excess oxygen using an electrical heater in the tank. It worked, but took 8 hours. But there was a still a problem. Due to an oversight in replacing a tiny and seemingly insignificant component when the tank design was modified for Apollo 13, the “boil-off” operation severely damaged the internal heating elements of the number 2 tank.
The Mission Objective
Apollo 13 was supposed to land so that the astronauts could explore the Fra Mauro formation, otherwise known as the Fra Mauro highlands on the moon.
Due to the failure of the Apollo 13 mission, the Apollo 14 mission was assigned the same objective and successfully completed it.
Houston, we have a problem
The mission launched on 11th April 1970. 5 1/2 minutes after lift-off, the command crew felt a little vibration in the Command Module. This might not seem like something to worry about, but when it comes to space travel, even the smallest things can have the biggest significance. This was followed by the centre engine of the S-II stage shut down two minutes earlier than it was supposed to. This meant that the remaining four engines had to burn for 34 seconds longer than was planned – not a big deal? Well, this then meant that the S-IVB third stage had to burn for nine seconds longer than planned to get Apollo 13 into orbit.
46 hours and 43 minutes into the mission, Capcom, Joe Kerwin is reported to have said “The spacecraft is in good shape as far as we are concerned. We’re bored to tears down here.”
The crew of Apollo 13 did a 49 minute broadcast that showed them living and working in the weightless atmosphere of space. It ended at the 55 hours and 46 minute mark of their mission with Jim Lovell signing off “This is the crew of Apollo 13 wishing everybody there a nice evening, and we’re just about ready to close out our inspection of Aquarius and get back for a pleasant evening in Odyssey. Good night.”
9 minutes later the oxygen tanks were “stirred” as one of the normal procedures of the Apollo missions. The number 2 oxygen tank exploded and caused the number 1 oxygen tank to fail. The command module lost it’s normal supply of electricity, light and water as well. At this point, the three men were 200,000 miles away from the Earth.
At 9:08pm on 13th April 1970, the words were uttered, “Houston, we’ve had a problem here.”
The mission became one of survival.
The Lunar Module was used as a lifeboat and the men had to ensure that it had the necessary supplies that would enable it to get the them back to Earth. The Lunar Module had been designed to sustain two men for 45 hours. This had to be stretched to 90 hours for three men. Oxygen on the Lunar Module wasn’t an issue, but power was a concern as there was no way to recharge the Lunar Module battery if it ran out of power and without power, the men wouldn’t be able to return to Earth. Running out of water was also a concern. The three men cut their water intake and reduced the power being used by the Lunar Module, meaning that they were far from comfortable. Reducing power meant there was little heat, save for that which the men’s bodies produced. The temperature in the Lunar Module dropped to 38 degrees Fahrenheit (just above freezing) and condensation formed on all the walls.
Though oxygen wasn’t a problem, the risk of carbon dioxide poisoning was. Though there were air scrubbers, the filters for the Lunar Module and Command Module were different. The men on the ground at NASA had to come up with a way of making the square filters of the Command Module fit the round scrubbers in the Lunar Module with the limited items that the men in the Lunar Module had on hand.
In order to return to Earth safely, the Lunar Module didn’t have the Command Module navigation system and in order to get them on the right course they had to executed a 35 second burn. A five minute burn rounding the far side of the moon also had to be completed.
Returning to Earth
When the power was turned on for the return to Earth, there was a serious risk of short circuits due to the amount of condensation on the walls, instruments and behind the panels.
Despite all these problems, the Lunar Module landed in the Pacific Ocean near Samoa on 17th April 1970 and was recovered by the USS Iwo Jima. The Apollo 13 mission lasted for 5 days, 22 hours, 54 minutes and 41 seconds and covered a distance of 622,268 miles.
According to NASA:
“After an intensive investigation, the Apollo 13 Accident Review Board identified the cause of the explosion. In 1965, the CM had undergone many improvements that included raising the permissible voltage to the heaters in the oxygen tanks from 28 to 65 volts DC. Unfortunately, the thermostatic switches on these heaters weren’t modified to suit the change. During one final test on the launch pad, the heaters were on for a long period of time. This subjected the wiring in the vicinity of the heaters to very high temperatures (1000 F), which have been subsequently shown to severely degrade teflon insulation. The thermostatic switches started to open while powered by 65 volts DC and were probably welded shut. Furthermore, other warning signs during testing went unheeded and the tank, damaged from eight hours of overheating, was a potential bomb the next time it was filled with oxygen. That bomb exploded on April 13, 1970 – 200,000 miles from Earth.”
Apollo 13: the movie
A movie about the Apollo 13 mission was released in 1995 and stared Tom Hanks as Jim Lovell, Kevin Bacon as Jack Swigert and Bill Paxton as Fred Haise. It was directed by Ron Howard and the screenplay was adapted from the books by Commander Jim Lovell and Time Magazine correspondent Jeffrey Kluger.
The movie not only looks at what the men in the spacecraft went through on their perilous journey through space, but also their families and those at NASA back on Earth.
Mightier Than the Sword UK Publications 
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