6
A Cold, Dark Journey
If you missed the entry corridor by a degree, that’s a real bad day.
—Jerry Bostick, NASA flight controller
As people around the world watched and waited, Apollo 13 zoomed toward Earth. Lovell, Haise, and Swigert saw the moon shrink behind them. They crossed into Earth’s sphere of influence, the point at which Earth’s gravity started to pull them in. The spacecraft gained speed, and the crew thought about the huge task that lay ahead of them. Soon they would have to abandon their lunar lifeboat. Without a heat shield, Aquarius could not get them home. Somehow, they had to bring the cold, dead command module Odyssey back to life. Was that possible from deep space?
Another Glitch
While Lovell and Swigert tried to sleep in Odyssey, Haise kept watch over Aquarius. He turned on a portable tape player and listened to the song “The Age of Aquarius.” He gazed out the window for a last look at the receding moon and heard a thump from somewhere under his feet. Then a whump-shudder shook the spacecraft. Outside the window, what looked like icy snowflakes drifted past.
A master alarm sounded, and a battery light went on for battery 2.
Haise informed mission control, and flight controllers in Houston began scanning their systems for an explanation.
Aquarius had four batteries. Mission control noticed that battery 2 was lower than it should be and was still falling. Battery experts checked it out and learned that battery 2 had exploded. It was a small blast, and the battery still worked. But it wasn’t producing as much electricity as it had before the explosion. Flight controllers assured the crew that batteries 1, 3, and 4 would pick up the slack for battery 2 and that it was a minor, survivable glitch.
But another glitch on top of all the previous glitches made Lovell nervous. After his nap, he pulled off the biomedical sensors glued to his chest. They were itchy, and turning them off would save precious power. Lovell knew that the next two days would be stressful. He didn’t like the idea of the entire world watching his heart rate climb.
Midcourse Correction
Apollo 13 was veering off course. In the eighteen hours since the crew executed the long speed-up burn, the spacecraft had drifted. To the flight controllers in Houston, it looked as if something was pushing the spacecraft off its carefully designed path to Earth. Odyssey was turned off. Only a few pieces of equipment were turned on in Aquarius. Mission control didn’t know what was causing the spacecraft to drift, but they knew they had to correct it.
When the spacecraft entered Earth’s atmosphere, it had to be within a narrow corridor. If it came in too shallow, it would bounce off like a stone skipping across a pond and head back into space for an endless orbit. If it came in too steep, the spacecraft would burn up in the atmosphere.
Apollo 13 was coming in too shallow.
The astronauts needed to perform another burn, this time with the computer and guidance system turned off to save the remaining precious bits of power. They would have to execute the burn manually.
Mission control saw another problem developing. The pressure in Aquarius’s helium tank was rising. The amount of pressure was important because helium moved fuel into the combustion chamber for engine burns. A pressure-relieving burst disk was built into the gas line. When the pressure got too high, it would vent helium out to space and relieve the pressure. But when the helium vented, it could throw the spacecraft farther off course. And if the helium vented, the crew would not be able to fire the engine.
Mission control worked on a plan to perform the midcourse correction burn before the helium blowout. To align the spacecraft before the burn, the crew used an old technique from Apollo 8. Lovell remembered testing the procedure on his earlier mission. The crew pointed Apollo 13 in the right direction by using Earth’s terminator, the line that separated day from night on the planet’s surface, as a reference marker. While Lovell sighted on Earth, Haise looked through the alignment telescope at the sun. The two points of reference confirmed the spacecraft was positioned correctly.
The astronauts worked together to perform the fifteen-second burn. Lovell fired the engine and controlled the spacecraft’s roll. Haise kept Apollo 13 oriented correctly. Swigert timed the procedure with his wristwatch. Once again, the astronauts proved they were terrific pilots. Apollo 13 was back in the center of the reentry corridor.
Three hours after the midcourse correction, the crew heard a dull pop and hiss beneath the floor of Aquarius. Lovell looked out the window. “I noticed a lot of sparklies going out,” he told mission control. Houston confirmed what the crew suspected. The helium burst disk had ruptured. Lovell noted that when the helium vented, the spacecraft changed the direction and speed of its passive thermal control roll. He talked it over with mission control. They decided that as long as the sun’s heat stayed evenly distributed by the roll, they would be able to leave it alone.
NASA space scientist and mathematician Katherine Johnson poses for a portrait at NASA’s Langley Research Center in 1966 in Hampton, Virginia.
Cold, Damp, and Yucky
The temperature in Odyssey hovered around freezing. The astronauts could see their breath. Water droplets formed on the walls, windows, and instrument panels. The combination of cold and damp chilled the astronauts. Lovell and Haise pulled on the heavy boots they would have worn on the moon to stay warm.
“Going back up into the refrigerator,” said Swigert when it was time for him to rest.
“I thought it was the bedroom,” said mission control.
“Well, it’s got a new name now because it is about 30 degrees [17°C] cooler.”
It was so uncomfortable in the command module that Haise stretched out in the 3-foot-wide (0.9 m) tunnel between Aquarius and Odyssey and tried to sleep there. Swigert slept on the floor of Aquarius with a restraint wrapped around his arm to keep from floating.
Since the explosion, the astronauts had stuck to their strict intake of 6 ounces (177 mL) of water per day. As the spacecraft approached Earth, they were beginning to feel the effects of dehydration. Focusing clearly was becoming more difficult. Haise felt feverish and achy. Their food choices were limited because they ate only food that didn’t need water. Some food packets were frozen. They lived on peanut cubes and sandwich spread. As the hours passed, their cozy home became far less cozy.
Normally, liquid waste was dumped out of the spacecraft through a venting system that shot it out into space. But since Apollo 13 kept drifting off course, mission control worried that venting urine would throw them farther off course. The crew had to store their liquid waste in plastic bags for the rest of the spaceflight. After a few days, bags of urine were everywhere.
The Last Twenty-Four Hours
The final day of the spaceflight was the busiest for the astronauts. Mission control gave the crew a detailed checklist of all their tasks to get ready for splashdown. The checklist gave instructions for each event and the exact time the astronauts would perform the tasks.
One of the first items was to recharge Odyssey’s batteries using power from Aquarius. During reentry, the spacecraft used reentry batteries to supply all of its power. After the explosion, Odyssey had automatically pulled power from one of its three reentry batteries to try to keep itself alive. “We’re 20 amp-hours short on one of the entry batteries, and we’ve got to juice that up to get you home,” mission control told the crew.
The astronauts worried the lunar module didn’t have power to spare. Wouldn’t Aquarius run out of power if it gave some to Odyssey? Also, Lovell pointed out, the procedure reversed the electrical currents from their normal paths. The command module fed electrical power to the lunar module, not the other way around. Would reversing the flow cause a short circuit?
Mission control reassured the crew. Turning off most of the lunar module’s equipment had conserved power so well that Aquarius had power to spare. Flight controllers explained the procedure to draw current from Aquarius to Odyssey. It had never been done or tested, but mission control felt it would work.
For three days, the crew had watched flight controllers solve problems that seemed unsolvable. They knew everyone at NASA was working as hard as they could to bring them home. And, as mission control reminded them, without a battery charge, there was no way the astronauts would make it back to Earth. The crew executed the procedure and charged one of Odyssey’s batteries for fifteen hours. Then they topped off another battery for about two hours.
While the batteries charged, the crew completed another task to prepare for reentry. They added weight to the command module. The calculations for reentry assumed moon rocks would be on board.
The crew transferred equipment from Aquarius to Odyssey to make up for the lack of moon rocks.
A Power-Up Plan
A team of engineers at mission control had been working continually to find a way to power up the command module for reentry. Normally, the power-up sequence took a full day. In a slow, precise process, technicians turned on each piece of equipment and checked it before moving on to the next. They used thousands of amp hours of ground power to warm up each system and make sure it worked properly. But the normal power-up procedure would not work on Apollo 13. Flight controllers had to find a way to bring the dead command module back to life using no more than 43 amps.
Flight controllers knew they could not turn on every system on the spacecraft. They had to figure out which systems to turn on, how much power they each would use, and the order for switching them on. They tried one configuration, then another, to come up with a plan that didn’t exceed the limited resources. Each time they updated the procedure, Ken Mattingly tested it in a simulator to make sure no glitches occurred when they passed the instructions to the crew.
The spacecraft would reach Earth on Friday, regardless of whether the plan was ready. Mission control worked to find a solution before time ran out.
The crew in space grew restless. They knew that they were tired and that could cause them to make mistakes. They wanted time to study the power-up plan and make sure all three of them clearly understood each instruction.
“Just a reminder,” Lovell told mission control. “It’s less than twenty-four hours to go.” He asked for any procedures they had, “so I can run through them with the crew and make sure we get all our signals straight.”
“Roger that, Jim,” said mission control. “We are trying to get the procedures finished and up to you as quickly as we can.”
Finally, the checklist was ready. Since 1970 was pre-internet, mission control could not email the plan to the crew. They weren’t able to upload the instructions from a powerful computer on the ground. Mattingly joined the mission control crew. He had tested the procedure in a simulator, so he read the instructions to Swigert—one line at a time.
It was slow going. Mattingly read an instruction. Swigert wrote it down using every scrap of paper he could find. Then Swigert repeated it, and mission control checked to make sure it was correct. Back and forth they went. Sometimes the communications signal dropped, and they had to repeat themselves.
It took nearly two hours for Swigert to copy the procedures. There were hundreds of intricate steps. And each one of them had to be exact. After Swigert finished the command module instructions, mission control read Haise the final checklist for the lunar module. The crew would not execute the plan for several hours. They studied it and discussed it. They made sure there were no conflicts between instructions for the command module and for the lunar module.
“If you have any questions,” Mattingly said, “after you mull it over, why, we’re always available. Just ask us what you’re thinking about.”
“Okay,” said Swigert. “That’s what we’re going to do.”
Before he signed off, Mattingly assured the crew that they had tested and retested the procedures. “We think we’ve got all the little surprises ironed out for you.”
“I hope so,” said Swigert, “because tomorrow is examination time.”