SCREENS AND CHARTS AT MISSION CONTROL changed. No longer was the spacecraft 202,700 miles from Earth; it was now 38,760 miles from the Moon. And it was picking up speed, passing 2,700 miles per hour and gaining by the minute.
At their consoles, controllers made printouts of their displays to commemorate the moment. Someday they would show these papers to their grandchildren and tell them what they’d seen.
A few minutes later, Collins radioed Apollo 8 with an update on their recent television broadcast.
“We are having a playback of your TV shows and are all enjoying it down here. It was better than yesterday because it didn’t preempt the football game.”
“Don’t tell me they cut off a football game,” Borman said. “Didn’t they learn from Heidi?”
Just a month earlier, as millions of Americans watched the New York Jets and Oakland Raiders battle into the final minute of a spectacular game, NBC stuck to its strict broadcast schedule, switching over at 7:00 P.M. to Heidi, a film about a young girl who was living with her grandfather in the Swiss Alps. Viewers erupted in protest, flooding the network with irate calls (and threats) and blowing out twenty-six fuses on the NBC switchboard while the Raiders scored two touchdowns in nine seconds to pull off a miracle come-from-behind win. The next day, The New York Times ran a front-page story on the debacle, and David Brinkley addressed it on the evening news—then showed tape of the game’s last minute. Even on this pioneering trip to the Moon, Borman wanted nothing to do with messing with his beloved game of football.
Thirty minutes after she’d arrived, Marilyn left Mission Control with astronaut John Young, who was going to drive her home.
“Have you seen Susan yet?” Young asked, then offered to take her over to the Borman house.
When they arrived, Marilyn found a familiar scene—loads of visitors, trays of food, kids pinballing between rooms, squawk boxes chirping. The only thing missing was Susan.
“She’s in the bedroom,” someone said. “I’ll tell her you’re here.”
Marilyn sat in the living room and waited, chatting with other visitors and fixing herself a drink. She kept waiting, for thirty minutes, an hour. After two hours, Susan still had not emerged.
I’m part of this just as much as you are, Marilyn thought. My husband is on this flight, too.
Marilyn didn’t know how painful things had been for Susan after the Apollo 1 tragedy. She didn’t know how clearly Susan pictured herself as a widow in the coming hours. If Marilyn had known any of this, she would have understood and would have tried to help. But Susan never showed that vulnerability to anyone, not even to Frank. As Marilyn waited, Susan remained curled up on the bed in her bedroom, listening for her husband’s voice on the squawk box. When Marilyn left, she left with hurt feelings.
Back at home, Marilyn found her house oddly empty. She poured herself a scotch on the rocks, sat on a stool at the wood-paneled bar in the family room, and sobbed. In just ten hours, Apollo 8 would disappear behind the Moon. How had she been so confident all this time? Her husband was disappearing behind the Moon. And that meant he might never come home.
At almost exactly two and a half days into the flight, Apollo 8 prepared for just its second—and final—midcourse correction burn of the outbound leg. It would be accomplished by firing four thrusters on the spacecraft, each of which could produce 100 pounds of thrust. That was only the tiniest fraction of the force that had been required to get Apollo 8 off the launchpad, but it was all the vehicle would need for eleven seconds as it refined its line to the Moon.
“Okay, stand by,” Borman called to his crewmates.
“Burn,” Lovell said.
“Burning,” Anders confirmed.
Eleven seconds later, it was done. Houston analyzed the telemetry—the correction had been nearly perfect, and it was just a matter of riding the ship for another eight hours until lunar rendezvous. Despite such close proximity, the crew still could not see its target. To all of them, it felt like sitting with their backs to the screen in a movie theater during a terrific thriller.
In Houston, the wives began to prepare for when the spacecraft reached the Moon, scheduled for 4:00 A.M. Houston time, when Apollo 8 would attempt a complex maneuver known as Lunar Orbit Insertion, or LOI. Engineers, mathematicians, physicists, and other scientists had spent years developing the calculations and determining how to make the maneuver work. But on its face, LOI was easy to understand.
At 69 hours into the flight, Apollo 8 would pass just in front of the Moon, missing its surface by only 69 miles. That altitude had been chosen for a reason. On future landing missions, it would be close enough so that the lunar module shuttling astronauts to the lunar surface and back wouldn’t require a massive amount of propellant, but far enough away to make it unlikely that the spacecraft waiting in orbit above would crash into the Moon.
If Apollo 8 did not fire its SPS engine—or if the engine failed to ignite—after passing behind the Moon, lunar gravity would cause it to slingshot around the far side and head back to Earth, requiring only minor course adjustments in order to hit its reentry corridor and splash down in the Pacific Ocean. NASA had chosen this free return, figure eight trajectory in case of engine failure or other in-flight problems.
But NASA planned for Apollo 8 to orbit the Moon. To enter lunar orbit, the spacecraft had to slow itself down enough to be captured by the Moon’s gravity. The only way to do that was to fire the SPS engine against the direction of its travel, for just the right amount of time—about four minutes—and with just the right amount of thrust.
If the engine fired for too short a period, or without enough thrust, the spacecraft might still slingshot around the Moon but emerge on an improper trajectory, one that might cause it to burn up on reentry into the atmosphere or miss Earth entirely. Or it might be cast out into space without enough power or propellant to reverse course and come back. Or it might enter a lunar orbit off-kilter enough to cause it to crash into the Moon.
If the engine fired for too long, or with too much thrust, the results might be even worse. That would slow down the spacecraft so much that the Moon’s gravity would overcome the ship and cause it to plummet into the lunar surface.
The SPS was the same engine that had failed to build up proper thrust on its test fire eleven hours into the flight, owing to the suspected helium bubble in a propellant line. Kraft and the controllers in Houston believed the problem had worked itself out, but that was just a best guess. They wouldn’t know for sure until the astronauts tried to light the engine again behind the Moon.
No aspect of the Lunar Orbit Insertion maneuver was easy. In training, the crew and controllers crashed into the Moon time and time again. Sometimes controllers became so anxious that they aborted prematurely or took needless emergency action, fracturing their confidence and planting doubts about their ability to work as a single cohesive unit. So shaken did some controllers become that they sometimes denied they’d made a mistake. To Kraft, that was even worse than the error. When denials happened, he’d stop the session, take the controller aside, and say, “I don’t want any bullshit from you anymore. If you make a mistake, you say you made a mistake.” Kraft demanded truth, and he demanded that everyone perform the maneuver again and again and again. With a few hours to go, he believed his team was ready.
Lunar Orbit Insertion involved an emotional component, too. After flying past the leading hemisphere of the onrushing Moon, the spacecraft would disappear behind its far side and lose contact with Earth, as all signals to and from the ship would be blocked by the Moon. For about thirty-five minutes, no one at Mission Control would have any idea whether the SPS engine had fired or performed well; no one would be able to monitor the spacecraft or its systems, no one would be able to talk to the astronauts. Controllers could only watch their clocks and hope Apollo 8 emerged from the far side exactly when it was supposed to. If it came out any earlier or later than that, something had gone wrong.
Anders had imagined he would watch the Moon closing in, as the pilots did in the film 2001: A Space Odyssey, until it filled the sky. Instead, he saw emptiness. Even Lovell, with the wide field of view from his telescope and sextant, couldn’t catch a glimpse of the Moon. Due to the position of the Sun (and the glare it caused) and the position of the spacecraft’s windows (facing mostly toward black space), it had been all but impossible for the crew to spot its target.
“As a matter of interest, we have as yet to see the Moon,” Lovell radioed to Houston.
“What else are you seeing?” asked CapCom Jerry Carr.
“Nothing,” Anders replied. “It’s like being on the inside of a submarine.”
In Houston, in the middle of the night, the astronauts’ wives turned their squawk boxes just loud enough to hear without awakening friends and family who were curled up on couches and in chairs throughout their homes. One by one, these supporters awoke to help the wives through Lunar Orbit Insertion. In the fog of nerves and excitement, few realized that it was now officially Christmas Eve.
Despite the hour, approaching four in the morning in Houston, visitors began to crowd into the viewing room at Mission Control. A hundred people sardined themselves into this room designed for far fewer, but all respected the flashing sign that requested QUIET PLEASE as Lunar Orbit Insertion drew near.
It was time for Mission Control to make a final decision. One by one, Flight Director Glynn Lunney polled each of his controllers, looking for a simple Go or No Go. One by one, they gave him their answer. Lunney looked at Carr, who radioed to the spacecraft, now just over three thousand miles from the Moon.
“Apollo 8, this is Houston. At 68:04, you’re Go for LOI.”
“Okay,” Borman answered. “Apollo 8 is Go.”
“You are riding the best bird we can find,” Carr said.
Thirty minutes remained until Lunar Orbit Insertion. Controllers continued to make final checks of the spacecraft and its systems, and to grow more nervous by the minute.
George Mueller had thought 69 miles was cutting it far too close to approach or orbit the Moon. “You don’t know that you’re that accurate,” Mueller had told Kraft when the mission was planned. “You don’t know that you can hit the Moon within sixty-nine miles as you’re aiming at this thing two hundred and forty thousand miles away. You don’t know that your radar is that good. You don’t know that your tracking is that good.” Kraft agreed that orbiting at a higher altitude would decrease the chance of error and catastrophe. But that wouldn’t have allowed NASA to best prepare for a lunar landing. So 69 miles it would be.
Mueller wasn’t the only one worried. Pacing the back row at Mission Control, the lead flight director, Cliff Charlesworth, who was off duty at the time, kept thinking, I know all our guidance systems are accurate, and we tracked it properly, and all the mathematicians in the world have looked at this thing. But sixty-nine miles is pretty close…
In a back room, John Mayer, chief of the Mission Planning and Analysis Division, began to receive visitors—Bob Gilruth, George Low, and other top managers, who’d arrived with a pressing, semiserious question:
“How sure are you we’re going to miss the Moon?”
On board Apollo 8, the crew had the same concern. Their spacecraft was now traveling more than 5,000 miles per hour. For its part, the Moon, 2,160 miles in diameter, was moving at more than 2,000 miles per hour. Could anyone really guarantee the ship wasn’t going to end up smashing into the massive orb?
At one console, Flight Dynamics Officer Ed Pavelka calculated the SPS burn data Apollo 8 required for its Lunar Orbit Insertion. Nearby, Jerry Bostick, chief of the flight dynamics program, the team responsible for the trajectory and guidance of the spacecraft, watched him check and recheck his calculations, not once or twice but nine or ten times, before passing them along to Carr for transmission to the astronauts.
Five minutes remained until Apollo 8 met the Moon. At home, Susan, Marilyn, and Valerie hung on every word from the squawk box.
“Apollo 8, Houston. Five minutes…all systems Go. Over,” Carr radioed to the crew.
“Thank you. Houston, Apollo 8,” Borman replied.
“Roger, Frank,” Carr said. “The custard is in the oven at three fifty. Over.”
That was a secret message from Susan to Frank. Long ago, he’d told her, “You worry about the custard and I’ll worry about the flying”—separating their duties was the only way to survive the toll a test pilot’s career exacted from a marriage and family. She’d wanted to let him know that all was good at home at a time he might need to hear it most.
“No comprendo,” Borman told Carr.
Susan couldn’t tell whether Frank hadn’t understood the words or had forgotten the reference. All she knew for sure was that she couldn’t reach him.
Two minutes remained until the spacecraft, now moving at 5,125 miles per hour, went behind the Moon. Since lift-off, Apollo 8 had traveled 240,000 miles, and the Moon had traveled 150,000 miles, to make this rendezvous.
“One minute to LOS [loss of signal],” Carr radioed to Apollo 8. “All systems Go.”
“We’ll see you on the other side,” Lovell said.
Outside Anders’s window, any trace of sunlight had disappeared, and as his eyes adapted to the intense darkness he began to see stars, it seemed like a million of them, so many he couldn’t even pick out constellations. The sight took his breath away. He looked to his right, through the window beside him, hungry for more, but suddenly there were no stars anymore—all of them had gone dark. There was just a giant black hole, as if part of the universe had vanished. The hair on the back of Anders’s neck stood up, and for a moment it felt as if his heart had stopped, until he realized that he wasn’t looking at a missing piece of the universe at all.
He was looking at the Moon.
A few seconds after that, Apollo 8 disappeared behind it.