The grave circumstances of Apollo 13 became a worldwide sensation. Television coverage broke in and reported routinely on the mission, in a special report scenario that harkened back to the assassination of President John F. Kennedy and other tragedies. Updates did not look particularly encouraging for some time, leading to a sense of panic and a feeling that a terrible calamity would result. The small supply of electrical power in the craft did not allow live television broadcasts, so news desks passed on the latest statements and updates, as broadcasters employed models of the spacecraft to try to explain to viewers what was happening and how the mission might end.

Lovell later wrote that using the LM as a lifeboat for three astronauts really stretched the limits of what it was intended to do: It was supposed to sustain two astronauts for about a day and a half rather than three astronauts for the four-day return to Earth. The command/service module produced water as a byproduct from its fuel cells. But such was not the case with the LM, which employed silver-zinc batteries, and so within the LM, vitally important electrical power and water were in short supply. Oxygen was less of a concern because the LM had enough to spare in order to repressurize the spacecraft’s atmosphere after each lunar surface activity. But Kranz and the astronauts all wanted to minimize the inherent risks, of course, so they powered down the LM as much as possible to preserve supplies. This also helped them keep communications and life-support functions as stable as possible until nearing reentry into Earth’s atmosphere.

Another looming problem that worsened as the cruise toward Earth continued was carbon dioxide. This, in fact, proved to be a challenging test for both the controllers and the crew alike. Removing carbon dioxide from the LM’s atmosphere would be critical — too much buildup of this gas would prove fatal. Carbon dioxide removal took place via lithium hydroxide canisters, and the LM lacked the number required to remove sufficient carbon dioxide for the return cruise home. Further, the backups were in storage, out of reach, and the command/service module lithium hydroxide canisters were incompatible with the LM. So ground controllers worked out a plan, communicated it to the crew, and the astronauts jury-rigged an outfit to accomplish the task, using hoses to connect the cubical command module canisters to the LM’s cylindrical sockets. They later referred to this arrangement as “the mailbox.”





Back home

As the craft approached Earth, the crew would have to power up the command module from scratch. This had never before been tried during a flight. Given the craft’s weak power availability, controllers Aaron and Mattingly proposed a procedure, but they were uncertain. The extremely cold temperatures within the spacecraft, which dropped as low as 39 degrees Fahrenheit (4 degrees Celsius), meant that water had condensed on surfaces and alarmed the crew and controllers, who thought of potential electrical shorts. But this did not, in the end, turn out to be a problem.

Another risky maneuver loomed. Before approaching Earth’s atmosphere, the crew would have to separate the LM from the command module. Ordinarily, the astronauts would employ the service module’s so-called reaction control system, with its thrusters, to accomplish this. But the craft’s power failure meant this was not operable, and the service module would be gone before the LM anyway. University of Toronto engineers, led by Bernard Etkin and called on by Grumman, worked on the problem for a day and proposed pressurizing the tunnel connecting the LM and the command module just prior to reentry. This, they proposed, would push the two craft away from each other. They communicated their slide-rule calculations to Mission Control, who sent them on to the astronauts. The procedure worked.

With Apollo 13 approaching home, the world watched, bound by hope. The sustained crisis brought people of all nations together as everyone wished for the astronauts’ safe return. News reports became ever more frantic, and despite the constant analysis, all that could now be done was to wait and hope.

As the crew moved toward Earth, they first separated the service module, pushed away from it using the LM’s thrusters, and then photographed the damage on the service module as the two crafts inched apart. They were stunned to see an entire panel on the side of the service module missing. Safely back within the command module, the crew then jettisoned the LM, and, within Odyssey, began reentry into Earth’s atmosphere. The blackout with Apollo 13 lasted six minutes, longer than expected, which heightened the drama on the ground terrifically.

But then, in a flash, communications returned, the craft was spotted, and Odyssey made a splashdown, its chutes out, in the Pacific Ocean, southeast of American Samoa. The amphibious assault ship, USS Iwo Jima, picked up the crew, and the world celebrated. In the end, the most dangerous circumstance in space exploration ended with a triumph. The astronauts missed walking on the Moon, but they lived to walk again on Earth. Lessons from this drama would help fuel the momentum of the Apollo missions to come.