Fortunately, somebody had already been working on that problem for months.
A Year Earlier, in the run-up to the Apollo 10 mission, the flight controllers and astronauts had been thrown a curveball during a simulation. "The simulation guys failed those fuel cells at almost the same spot," as when Apollo 13's oxygen tank exploded in real life, remembers James ("Jim") Hannigan, the lunar module branch chief, "It was uncanny."
Legler had been present for the Apollo 10 simulation when the lunar module was suddenly in demand as a lifeboat. While some lifeboat procedures had already been worked out for earlier missions, none addressed having to use the lunar module as a lifeboat with a damaged command module attached. Although Legler called in reinforcements from among the other lunar module flight controllers, they were unable to get the spacecraft powered up in time, and the Apollo 10 simulation had finished with a dead crew.
"Many people had discussed the use of the LM as lifeboat, but we found out in this sim," that exactly how to do it couldn't be worked out in real time, Legler says. At the time, the simulation was rejected as unrealistic, and it was soon forgotten by most. NASA "didn't consider that an authentic failure case," because it involved the simultaneous failure of so many systems, explains Hannigan.
But the simulation nagged at the lunar module controllers. They had been caught unprepared and a crew had died, albeit only virtually. "You lose a crew, even in a simulation, and it's doom," says Hannigan. He tasked his deputy, Donald Puddy, to form a team to come up with a set of lifeboat procedures that would work, even with a crippled command module in the mix.
"Bob Legler was one of the key guys," on that team, recalls Hannigan. As part of his work, Legler "figured out how to reverse the power flow, so it could go from the LM back to CSM," through the umbilicals, says Hannigan. "That had never been done. Nothing had been designed to do that." Reversing the power flow was a trick that would ultimately be critical to the final stages of Apollo 13's return to Earth.
For the next few months after the Apollo 10 simulation, even as Apollo 11 made the first lunar landing and Apollo 12 returned to the moon, Puddy's team worked on the procedures, looking at many different failure scenarios and coming up with solutions. Although the results hadn't yet been formally certified and incorporated into NASA's official procedures, the lunar module controllers quickly pulled them off the shelf after the Apollo 13 explosion. The crew had a copy of the official emergency lunar module activation checklist on board, but the controllers needed to cut the 30-minute procedure to the bare minimum.
The lunar module team's head start stood them in good stead. Although Liebergot and his team had initially estimated 2 hours of life left in the last fuel cell when Kranz had asked Heselmeyer and his team to start working up how to get life support running in the lunar module, the situation was rapidly worsening. By the time the crew actually got into the Aquarius and started turning it on, the backroom controllers estimated there were just 15 minutes of life left in the last fuel cell onboard the Odyssey.
This article is presented in three parts. For part two click here.
