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Apollo 13

18 Feb

Apollo 13 may be the most well known Apollo mission, save for the first lunar landing mission, Apollo 11. It included a crew of three, Jim Lovell, Jack Swigert and Fred Haise. It was also conceived to be a lunar landing, but that part of the proposed mission was aborted after two days into the flight when an explosion of an oxygen tank damaged the service module. The flight had launched on April 11, 1970 from Cape Kennedy. It was the seventh manned mission of the Apollo series and was intended to be the third to have included a lunar landing.

Image credit: NASA

Apollo 13 could have easily ended in tragedy, since the service module’s systems were critical to the completion of the mission as it had been planned. The service module was intended to provide life support and maneuvering capabilities, among other functions. In an oversimplification of the actions taken to save the crew and return them back to Earth, the astronauts shut down the systems of the command module, in an effort to preserve resources for reentry and landing, and moved into the lunar module. Mission Control, headed up by lead flight controller Gene Kranz, quickly improvised a revised plan that included the spacecraft making a loop around the moon, exiting the lunar orbit at just the right point, returning to Earth, reentering Earth’s atmosphere and a splashdown. Numerous issues had to be dealt with and new procedures developed to safely accomplish this.

The explosion occurred just under fifty-six hours into the mission, shortly after the crew had completed a television broadcast which, not surprisingly, was not even carried by American television networks. The public had grown somewhat complacent with the space program after two successful lunar landings. Jim Lovell later said that the scheduled action to stir the oxygen tanks was routine and designed to make sure that the liquid in them was properly mixed in order that their gauges would provide accurate readings. Jack Swigert was instructed to trip switches that engaged fans inside the tanks. Ninety-some minutes after he did, he crew heard a bang and an alarm sounded. Personnel on the ground were also monitoring the instrument readings and realized that they were irregular. Lovell reported back to Houston what had happened and that the crew observed that material was venting out into space. One of three oxygen tanks appeared to have completely emptied and a second was also losing oxygen. On the ground, efforts quickly changed to focus on bringing the crew back alive. Lovell would later say that the astronauts themselves had no immediate ideas about how to complete the flight and return to Earth.

The lunar module was the section of the spacecraft designed to support two of the astronauts on the surface of the moon for two days. In the revised plan it became the “lifeboat” for the three crew members for the four days of the flight, should it be possible to complete it. The issues included having limited power, not much potable water and poor environmental conditions. Further difficulties included the buildup of carbon dioxide from the exhaled breath of the crew. The ground personnel and the astronauts dealt with these and many other issues and the crew returned to Earth on April 17, 1970.

There were many people responsible for the completion of the flight and dealing with all the issues that arose, one of which issues was to deal with the buildup of carbon dioxide in the lunar module. Around the time the spacecraft looped around the moon, carbon dioxide monitors began to register high levels. This was not a completely unknown eventuality, since one aspect of the training included a similar scenario in which the astronauts might have to use the lunar module in such a manner. One of the complications was carbon dioxide buildup. Astronaut Ken Mattingly had initially been selected to be one of the three astronauts but was grounded in favor of Swigert after Mattingly was determined to have been exposed to German measles. Mattingly was extremely familiar with the spacecraft, and helped the ground personnel improvise a carbon dioxide “scrubber” using a scavenged filtration canister from the command/service module (they were attached to one another). The scrubber of the lunar module was circular in shape, whereas the device from the command/service module was rectangular. Both scrubbers operated by channeling air through a filter that not only trapped particles but by using lithium hydroxide, also filtered carbon dioxide. Devising a makeshift method that required duct tape, plastic bags, cardboard, an air hose from a space suit and the command/service module canister, the ground personnel relayed the procedures to the astronauts who were able to recreate the improvised filtration system for the lunar module.

Another of them was engineer John Aaron. Aaron had been born in the Texas Panhandle town of Wellington and raised just across the state line in Oklahoma. He had started his college education at Bethany Nazarene College and finished at Southwestern Oklahoma State in Weatherford with a degree in physics. Aaron had been hired during the Gemini program and was serving as EECOM (electrical, environmental and communications officer) on Apollo 13. His interesting account of Apollo 13 (and the rest of his career) is available in three oral history interviews on the NASA website. When the explosion occurred on Apollo 13, he was at home shaving, getting ready for his shift. He received a call from NASA describing the situation and remembered observing that the spacecraft’s displays indicating depleting oxygen levels did not sound like instrument failure to him, but rather pointed toward a serious hardware issue. Aaron contributed to the decision to shut down the command module, realizing that another problem would be the order in which the module was powered up for reentry, also to be as certain as possible that there would be enough battery power to do so. He and his associates had no kind of simulator on the ground, but worked out the power-up procedure using graph paper, slide rules and arithmetic. They came up with a check list of the timing and order in which this sequence was to be performed. He also recalled when they rushed into Mission Control with the completed check list, they were immediately asked by other controllers “Where’s my copy?” Accordingly, they quickly ran back and made copies for the others. The sequence of steps was then relayed to the astronauts who executed them perfectly.

Aaron recounted that his team’s preparation (and his personal orientation) included trying to consider “what if” problems. Because spacecraft systems are so integrated, he tried to learn as much as he could about other systems beside those of his responsibility. In his comments, he was quick to give credit to all the other teams that worked on Apollo 13, those on the ground as well as the astronauts. He also noted that during the crisis, he and his group were so compartmentalized that they were not even aware of some of the other issues, including carbon dioxide buildup. Likewise, he observed that the astronauts had done a first rate job of dealing with everything, given the harsh environment in which they were working.

Many hardware modifications were made as a result of the Apollo 13 mission. The program continued with more successful lunar landings.

Several good books have been written about this mission, including astronaut Jim Lovell’s book originally titled “Lost Moon.” Numerous documentaries and films have also been made, including the 1995 feature film directed by Ron Howard. Despite the necessary time compression and having to condense four days into the better part of two hours, the 1995 film gets high marks for historical and factual accuracy.

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Posted by on February 18, 2021 in space program

 

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