Apollo 13: How Aquarius and a Makeshift CO2 Adapter Saved the Crew

Roughly 320,000 km from Earth, on its way to the Moon, Apollo 13 began losing the oxygen and electrical power that kept its three-man crew alive. Jim Lovell, Fred Haise and Jack Swigert had lifted off from Florida on April 11, 1970, bound for the lunar highlands of Fra Mauro. Lovell and Haise were to descend to the surface while Swigert stayed in orbit. The landing never happened.

The crew and the two spacecraft

Swigert had joined the crew shortly before launch. Ken Mattingly, the original command module pilot, had been exposed to German measles and lacked immunity. The command module Odyssey carried the heat shield for returning to Earth. Behind it, the service module supplied oxygen, electrical power and the main engine. The lunar module Aquarius was built to take two men down to the Moon and back into lunar orbit. The two craft travelled joined together on the outward journey.

The explosion

On the evening of April 13, Houston time, the astronauts finished a television broadcast. Minutes later, during routine checks, ground control asked for the oxygen tanks to be stirred, using fans inside the tanks to mix their contents. Then came a bang: an oxygen tank in the service module had ruptured. Swigert called the ground: "Okay, Houston, we've had a problem here." Lovell looked outside and saw material venting into space. The fuel cells depended on oxygen to generate electricity and water, so the failure spread through the resources the mission needed.

Aquarius as a lifeboat

Controllers had to save Odyssey's batteries for the return, so the crew moved into Aquarius and powered down the command module. Aquarius still had oxygen and power but now had to support three men far beyond its planned role. Ground teams calculated what could stay on and how much water the cooling system could use. A burn of Aquarius's engine put the craft on a path around the Moon and toward Earth, and after passing the far side, a longer burn shortened the return.

The carbon dioxide problem

Aquarius's system could not remove carbon dioxide fast enough for three people. Odyssey's spare absorbing cartridges did not fit the lunar module's equipment. Engineers on Earth worked only with materials the astronauts had aboard: plastic bags, cardboard, a suit hose and tape. They designed and tested an adapter and talked the crew through assembling it. It did not repair the oxygen tanks or make new oxygen, but it solved the immediate carbon dioxide problem. The cabins grew cold, the men rationed water, and sunlit debris and vented material could interfere with star sightings, so procedures were adapted using other references, including Earth, to check orientation.

Restarting Odyssey and return

Checklists were rebuilt around the power the crew could afford, so the command module had to come alive in the right order. Before re-entry they separated the damaged service module and photographed it; a whole outer panel was gone. They then abandoned Aquarius. Investigators later traced the failure to the oxygen tank's troubled history, including damage associated with ground heating before launch.