Excerpted with permission from Neil Armstrong: A Life of Flight, by Jay Barbree. Available from Thomas Dunne Books. Copyright © 2014.
A Thor–Agena rocket rose from California’s Vandenberg Air Force Base carrying another photoreconnaissance spy on its mission of keeping watch on what was happening at Russia’s launch site.  Come the following morning, analysts were looking at another Soviet heavy-lift Proton rocket sitting on its launch pad.  It was waiting to be outfitted with a Zond spacecraft.
Time was critical.
As they had done with the Zond loaded with tortoises, flies, and worms, the Russians were now in a position to dispatch a single cosmonaut on a circumlunar flight in December or January.
NASA’s top executives were in a quandary.  They saw failure before them.  NASA administrator Jim Webb told President Lyndon Johnson it was time for America to gamble, to consider putting astronauts on the Saturn-Five rocket’s first manned flight, and send them all the way to the moon aboard Apollo-Eight.
Some experts scoffed at the plan.  Most argued for it, and Webb told the outgoing president that it was the consensus of NASA engineers that they had corrected the Saturn-Five’s minor problems and there was no need for an additional unmanned test.  It was time to fly.
America wasted time with a test of the Redstone that proved to be useless permitting Yuri Gagarin to beat Alan Shepard into space.  Deke Slayton, NASA's director of flight crew operations, and NASA’s astronauts weren’t about to see a repeat of that little dog and pony show.   The Lunar Module would not be ready for its first flight test for four or five months, but they had a perfectly good Apollo and Deke turned to Apollo-Eight Commander Frank Borman, later saying, “The sonofabitch almost turned handsprings when I told him there was a possibility Apollo-Eight would go all the way to the moon.”
Deke laughed. “Borman’s answer was an overwhelming yes,” and then Deke told Apollo-Eight’s backup commander, Neil Armstrong’.
Neil assured the boss with the success of Apollo-Seven, the idea of sending Apollo-Eight to the moon was a masterful stroke of genius.  He had been talking to his friends in intelligence and Neil told Deke, “We should not only go, we should put Apollo-Eight in orbit around the moon too.  This would kill their plans to fly circumlunar.”
Deke nodded.  He liked Neil’s advice.
#            #            #
On November 11th, 1968 the new NASA administrator, Thomas Paine, approved the plan.  He phoned his decision to the White House, and President Johnson gave his blessing.
It was the single greatest gamble in spaceflight then, and since.
Every second of time was essential.
Apollo-Eight was readied for launch December 21, 1968, and Neil awoke with the prime crew.  Frank Borman, Jim Lovell, and Bill Anders began suiting up as Neil hustled over to the launch pad and climbed aboard the moon bound spacecraft.  It was the job of the backup commander to monitor the prelaunch sequence from inside the cockpit.  He was there to check and set all switches.
When the suited prime crew arrived in the white room, Neil shook their hands and retreated to the Launch Control Center where he joined his backup crew, Buzz Aldrin and Fred Haise.  The three staked out great viewing spots along the big window facing the pad and turned their ears to the speakers and the voice of launch commentator Jack King.
“Ten, nine, eight, seven, six,” and the Saturn-Five was alive.
But it didn’t go anywhere.  Neil knew the giant rocket consisted of millions of parts and systems.  The Launch Control Center’s computers worked at the speed of light checking and rechecking every single part before the most powerful machine ever would be permitted to move.
But its sound didn’t stay put.
Its thunderous roar came to life with Saturn-Five’s ignition and tore its way across the space center, hammering everything in its way.  The wide Launch Control building was no exception.
The tsunami of thunder slammed into the nerve center’s windows, buckling the big one before Neil and crew who for a moment thought they’d bought it.  They thought all glass had shattered and they stepped back as newly built ceiling parts fell along with other construction leftovers.
But the windows held and Neil could easily see the Saturn-Five’s powerful engines were burning even fiercer, demanding they be unleashed, and Jack King reported, “All engines running,
And then it happened.  Explosive bolts fired and the Saturn-Five’s giant hold down arms released their grip.
“We have liftoff, liftoff of Apollo-Eight – destination Moon.”
Neither Neil nor any among the huge assemblage surrounding the launch pad could take their eyes off the enormity of it all:  Saturn-Five moved.  That largest machine ever created reached for sky, rode on flame and roared, pounded ears, overwhelmed all those watching, slammed crackling thunder into  their bodies, fluttered their clothes, rolled their flesh in small yet perfect patterns, and rattled the coins in their pockets.  Neil Armstrong suddenly knew he couldn’t wait for the day he’d be riding that beautiful son-of-a-bitch.
Birds fled from their roost.  Wildlife ran from the stunning and numbing sound.   It pounded and leapt and trampled until it was no longer thunder, no longer roar.  It turned into a series of staccato explosions and now it hurt.  It brought a terrible crackling pain to the ears, assaulted the body, yet exhilarating and worth the beating as the great assemblage stared into the blinding mass of fire.
Higher and higher Apollo-Eight climbed, leaving its ear-shattering sound behind as it reached for orbit on a spear of flame more than 800feet in length, and the mass of spectators could only stare deeply into its flaming thrust, watch it turn into a rich orange, watch as red appeared along its burning edges and each sought a final last sighting as the pounding chariot drawn by thrust and driven by fire disappeared over the Atlantic and Neil Armstrong knew if one could love a machine he loved this one.
#            #            #
On board Frank Borman, Jim Lovell, and Bill Anders had just pushed through the region of maximum dynamic pressure, their spaceship leaving all sound behind.  It was eerily quiet now.  Had the astronauts not heard the humming of electronics, they might have thought they were in a simulator on the ground.
They sure as hell weren’t.
Something was slamming their growing weight back into its seat, hauling them faster and faster into space and it was all working and by the time they neared the speed needed to orbit Earth they had burned and discarded the rocket’s first and second stages.  Now all they needed was a push from its S4B third stage to begin circling Earth.
They got it and Mission Control began checking and rechecking all of Apollo-Eight’s systems again.  They had to be as sure as possible it had survived the rigors of launch and its ride into orbit and all would be well for the farthest and the longest journey yet by humans.
The checks and tests lasted for nearly two Earth orbits.  Apollo-Eight was set. 
The crew then fired the S4B stage again.
The final burst of energy from their Saturn-Five’s final stage increased the astronauts speed more than 7,000 miles per hour.  The rocket burn was what space navigators called translunar insertion, and Apollo-Eight’s new speed of more than 24,000 miles per hour broke the grip of Earth’s gravity.  The spaceship with a crew of three was free to cross the void to the moon.  But no sooner than the astronauts had gotten started, Jim Lovell sent a message back to Mission Control.  “Tell Conrad he lost his record.”
Pete Conrad and Dick Gordon had reached a height of 739 nautical miles in their agile Gemini-Eleven spacecraft.  But Apollo-Eight was still climbing and when it was done the new record would be some 240,000 miles.
#            #            #
Inside Launch Control Neil had monitored every happening on board the moon-bound ship.   But now it was time for him and the backup crew to get moving – back to Mission Control to monitor hopefully Apollo-Eight become the first manned spacecraft to enter an orbit around the moon.  He and Buzz and Fred with their wives boarded a NASA Gulfstream aircraft for the flight back to Houston.
When home Neil showered, changed his clothes, and then drove to Mission Control to standby if needed.
He was there in his capacity as Apollo-Eight’s backup commander.  If any of the flight controllers needed to know what the crew was scheduled to be doing at any given moment, he was their man.  Otherwise he took a “stay-out-of-the-way” seat in the big room full of consoles.
Deke Slayton saw Neil and thought this would be a good time to talk about his next assignment.  He came over and pulled up a chair.
“Got a minute, Neil?”
“Sure Boss, anytime.”
“Been thinking about your next assignment.”
“That’s great.”
“There’s lots of if, ands, and buts,” Deke said flatly, “but we’re thinking about you commanding Apollo-Eleven.”
“That wouldn’t make me mad,” Neil grinned.
Deke leaned forward and in an almost whisper explained there was no way of knowing what Apollo-Eleven’s mission would be.  But, if Apollo-Eight’s current flight to orbit the moon was a success, if the Lunar Module could pass muster in its Earth orbital first flight with Apollo-Nine, and if Apollo-Ten could return to lunar orbit and its Lunar Module could descend to within 8.4 miles of the moon, then Apollo-Eleven could be the first to land.
Neil wasn’t easily stunned, but he was for a long moment.  He just looked at the Director of Flight Crew Operations, processed everything he had been told. “Thanks Deke, thanks for your confidence,” he said offering him his hand.  “If you decide to trust me with Apollo-Eleven, you’ll get my best effort.”
“I know we will, Neil,” he assured him, adding, “It’s shaking out that way.”
#            #            #
Deke walked away and Neil reflected on the stunning possibility his crew just may be the first to set foot on a place other than Earth.  But certainly not lost on Neil despite what he’d just been told the marvelous product of science, technology, and engineering that would take him and his crew there was at this very moment moving between Earth and the moon -- the Block II Apollo command module created from the ashes of Apollo-One.  It was crammed with the knowledge learned from NASA’s astounding misjudgment.
The three astronauts riding within the cone-shaped, tiny world of their vessel were doing so under the watchful eyes of the largest audience in history.   More than a billion were tuned to their radios and televisions receiving reported sights never before seen.
Live views from a receding Earth came into homes from the spaceship, and its crew played tour guide.
#            #            #
Meanwhile on the steppes of Kazakhstan Zond was left standing on its launch pad.   Disappointment replaced the usual holiday round of vodka and cognac toasts.
Lev Kamanin, top aide to Kremlin space officials and the son of the chief of cosmonaut training wrote in his diary:
For us this day is darkened with the realization of lost opportunities and with sadness that today the men flying to the moon are named Borman, Lovell, and Anders, and not Bykovsky, Popovich, or Leonov.
No matter how well he said it, Kamanin’s sentiment was not the end of Russian efforts to reach the moon.  Despite failures with their big rockets, the cosmonauts would continue to try.
#            #            #
The hours in Apollo-Eight’s flight clicked away – day one and now day two -- but not the awe and wonder.   Armstrong knew the astronauts were fascinated, unable to take their eyes off what was out there.  They were suddenly aware of a distant sphere easing into view -- a stunning view of Earth.  Not vast horizons curving gently away, but a more than half-full Earth – a blue marble with dominating blue seas and white clouds, bountiful rain forests and mountains rising above its surface.
From midway between their home and the moon, Earth appeared to them as perfectly round, a stunning sphere and Apollo-Eight rolled on with Earth sliding silently out of sight leaving the astronauts a universe that was for the first time on their trip totally dark.  No more Earth glow, no more moon glow, even the sun had hid itself, and Borman, Lovell, and Anders had the most clearly, the most distinct view possible of their own Milky Way and hundreds more galaxies with their nebulas and star clusters – some so bright and far away – billions of light years back in time.
Tomorrow would be Christmas Eve.  That Borman, Lovell, and Anders were approaching the moon seemed impossible.  They had left Earth riding America’s largest rocket.  The mightiest energy machine ever built to lift straight up and away from the deep gravitational well of their planet.  A monster of steel and ice and fire atop which no man had ever before flown, and they were risking everything to fly into orbit around Earth’s natural satellite.
It was a gamble like few others known to history.
#            #            #
Apollo-Eight slipped across the equigravisphere that point in their flight where the moon’s gravity would have a greater pull than distant Earth.  In Mission Control Neil and Deke Slayton grabbed some fresh coffee and lost themselves in one of the control center’s back rooms.
“Mike Collins has recovered well from his neck operation,” Deke began, “How would you feel about having Collins and Buzz Aldrin as your crew?
“No problem,” Neil assured him.  “I’ve been working these last months with Buzz on the backup crew for Apollo-Eight, and everything went well.”
“No problems?”
“I could make Jim Lovell available.”
Neil was taken a bit aback.  He was aware some had difficulty getting along with Buzz, but not him.  And there were none better than Jim Lovell and Mike Collins and that begged the question, which would fly which?  Would Mike still be Command Module Pilot and Jim land on the moon or would Lovell the most experienced Command Module Pilot in the corps remain in that slot leaving Mike Collins to move over as Lunar Module Pilot?
Neil asked Deke, “Isn’t Jim Lovell commander material?”
“Yes, definitely,” Deke agreed.
“I wouldn’t want to interfere with Jim commanding his own flight.”
“Understand -- just wanted to give you options,” Deke told him.  “Let’s both think about it overnight.”
“Good idea, Boss,” Neil nodded, quickly reminding himself experience should be his chief consideration for a crew.
Buzz Aldrin had nailed the EVA thing in Gemini-Twelve and Mike Collins was at the top of his game in flying the Apollo command module, but at this moment Jim Lovell was at the helm of Apollo-Eight’s command module.
And another big item he would later tell me was, “If we switched things around too much, getting other people’s nose out of joint because we stole somebody from somebody else’s crew, we could make enemies.
“And there were personalities – always personalities and that’s one where I came up short,” Neil laughed, taking a good-natured jab at himself.
#            #            #
With the moon getting closer Apollo-Eight’s astronauts were waiting for Mission Control’s decision on whether or not they would slide into lunar orbit.
The three astronauts did not know if they would be spending Christmas circling the moon or making a single trip around its far side.  Either way their flight was already a smashing success.  It had opened the door to human exploration of our solar system, but, and it was a big but, everyone in NASA as well as the world’s billions in the radio and television audience wanted Apollo-Eight to go all the way.
Neil knew in the astronauts’ service module was the SPS, Apollo-Eight’s largest rocket.  It would be needed to reduce their speed to place them in lunar orbit, and then ignite again to bring them safely home.   The question in Mission Control was, “Is lunar orbit the safe thing to do?”
Neil also knew what the decision makers must consider was critical not only to the mission but also to the lives of the three men.  To slip Apollo-Eight into lunar orbit, the big SPS had to fire at full thrust for precisely 247 seconds.  Following shutdown, the crew would use its attitude-control thrusters to point the nose of its ship in the direction of flight.  If the engine burn faltered or failed early, the astronauts would soar past the moon on a path that would not return them to Earth.  If the rocket burned too long, Apollo-Eight would crash somewhere on the lunar landscape.
If SPS failed to ignite altogether, or if Mission Control decided not to go for lunar orbit, Apollo-Eight would be perfectly safe.  It would swing around the far side of the moon, curving in its sharp orbit as if it were a celestial boomerang and, without using an ounce of rocket fuel the astronauts would be on their way home.  This was the “Free Return Trajectory” inserted into Apollo-Eight’s computers before it left Earth.
Neil leaned back in his chair knowing this was Mission Control’s “moment of truth.”  He also knew all the control center’s monitors were “green.”
#            #            #
Astronauts Frank Borman, Jim Lovell, and Bill Anders were ready for any emergency.  They were about to disappear behind a two-thousand-mile-wide celestial body – fly across the side of the moon facing away from Earth where signals between Apollo-Eight and Mission Control would be blocked for more than twenty minutes.
CapCom Jerry Carr received the nod.  It was his job to give the astronauts their answer and everyone crossed his or her fingers to hear.  “Ten seconds to go,” he told Apollo-Eight.  “You are ‘GO’ all the way.”
Jim Lovell’s voice was incredibly calm.  “We’ll see you on the other side, Houston.”
With those words Apollo-Eight vanished behind Earth’s closest neighbor.
#            #            #
Neil listened.   But there was nothing to hear.   The mission had simply gone quiet.  No communications.  No telemetry signals.  No way of knowing if the three astronauts continued to exist.
What Mission Control couldn’t know until Apollo-Eight emerged from behind the moon was at the precise moment dictated by its flight plan, Jim Lovell fired Apollo-Eight’s biggest rocket for 247 seconds, a time he would later call the “longest four minutes I’ve ever spent.”
It was a splendid, epochal moment sixty-nine hours and fifteen minutes after launching from Earth, and when the rocket burn was completed, Apollo-Eight had locked itself into lunar orbit.
#            #            #
Mission Control only knew it should have happened, and the flight controllers continued their cliff-hanging suspense, counting the minutes and seconds before Apollo-Eight would emerge from the other side of the moon. 
CapCom Jerry Carr could only keep up his persistent call, “Apollo-Eight . . .    Apollo-Eight . . .    Apollo-Eight . . .  ”
It seemed like an eternity but then the intense clock-watching was over. Headsets and speakers crackled, and Neil heard the voice of Jim Lovell calm as always, “Go ahead, Houston.”
Those three words – coming just at the instant they should have – sent Mission Control into a bedlam of cheering, whistling, shouting, and slapping one another on the back.
Apollo-Eight’s telemetry flashed numbers on the big viewing board.  It was in an orbit 60 by 168.5 miles above the moon.  Later, on the third trip around the lunar surface, the ship’s big rocket fired again and dropped the astronauts into the desired, nearly circular orbit of 60.7 by 59.7 miles.
But the thrilled global audience didn’t want numbers.  It wanted to know what does the moon looked like.
“Essentially gray, no color,” reported lunar tour guide Jim Lovell.  “It’s like plaster of Paris or a sort of grayish beach sand.”
In their first two telecasts, the astronauts transmitted video from lunar orbit of the wild and wondrous landscape pitted with massive craters.  “It looks like a vast, lonely, forbidding place, an expanse of nothing,” said Borman as Lovell saw the distant Earth as a “grand oasis.”
The third member of the crew Bill Anders added, “You can see the moon has been bombarded through the eons with numerous meteorites.  Every square inch is pockmarked.”
Lovell added, “The vast loneliness is awe-inspiring, and it makes you realize just what you have back there on Earth.”
#            #            #
That Christmas Eve in 1968 was extraordinary not just for Neil and Deke and the others in Mission Control, but for the billions that had been brought together before their television sets.   They were seeing wondrous never-before-seen video of the moon moving quietly below Apollo-Eight’s lunar orbit when Bill Anders spoke.
“For all the people on Earth,” he began soberly, “the crew of Apollo-Eight has a message we would like to send you.”  He paused briefly and began reading from the verses of the book of Genesis:
“In the beginning, God created the heaven and the Earth . . .”  As Bill concluded the fourth verse, Jim Lovell read the next four with Frank Borman concluding with, “And God called the dry land Earth, and the gathering together of the waters He called seas.  And God saw that it was good.”
The moon with its view of the distant, soft blue marble of life had become host to poets, and Borman signed off with, “And from the crew of Apollo-Eight, we close with good night, good luck, a Merry Christmas, and God bless all of you – all of you on the good Earth.”
#            #            #
Neil clutched his emotions thinking, I hope my Mom saw this.  She would have enjoyed it he told himself rising from his chair.
His thoughts returned to the questions of the moment.  If what he and Deke had been talking about comes to be, he’d be there soon, possibly on the moon itself, and Neil went off to find Deke.  They had agreed on a final meet.
The two found an out-of-the-way niche again in the back of Mission Control.   When each had their say Neil was content that Mike Collins and Buzz Aldrin would serve with him on Apollo-11.   Jim Lovell, Bill Anders and Fred Haise would be their backups.
“I’ll be announcing the crews next month,” Deke told Neil, and when I saw him later, Neil told me off the record he would likely command Apollo-Eleven.
“Doesn’t surprise me a bit,” I nodded, smiling.  “You are obviously the most qualified pilot.  But possibly more important, you have the character and training to handle it.”
“Maybe,” he said.  “It was the luck of the draw.”
I knew this man standing before me never lobbied to make the first landing.  He never sought any more consideration than his fellow astronauts, and I could only stare at him.  I was amazed this humble man truly believed he was only selected because he was next in line.
I understood why the other astronauts believe that, but there was no question in my mind the engine driving this selection was the NASA bosses awareness of Neil’s devotion to flying the Lunar Landing Training Vehicle until he had this landing on the moon thing nailed along with his incessant drive to know what to expect.  He simply had to be prepared for the unexpected all the time not forgetting Neil had been a NASA test pilot for years.  That shooed away for them the military competition thing.  
“This is off the record,”  I told Neil. “As you know Deke and our man Harold Williams are fishing buddies, and he told Harold straight out he wanted you first, and if you had to abort he knew Conrad could handle the job on Apollo-Twelve, or if not Conrad, Jim Lovell could get it done on thirteen.”
Neil gave me a little smile that said maybe yes or maybe no, and I stood there admiring the raw fairness of this man.   I told him sincerely, “Neil you are too good.  You are the most considerate person I’ve ever met, and you may not think you’re special but everybody else does.  And dammit,” I raised by voice, “if you ever need me to run interference for you just let me know.”
Neil nodded and gave me the greatest compliment of my life.  “I’d like you as my blocking back anytime,” he smiled.
“Just ask,” I said knowing the best part was he was sincere.
#            #            #
Early in the morning of Christmas Day, Apollo-Eight moved through its tenth and final orbit around the moon and was again out of contact with Mission Control.  The critical rocket firing would either start them on their journey home or leave them stranded in lunar orbit.  At the appointed moment, Borman, Lovell, and Anders felt their big SPS rocket come to life creating a long stream of flame and a wide plume of fire behind the engine.
On the 304th second the engine shut down, right on the mark.
Time dragged maddeningly for a waiting world.
Finally, “Please be informed there is a Santa Claus.”  Jim Lovell’s voice was pure joy.  “The burn was good.”
It was better than that.  After twenty great hours in lunar orbit, Apollo-Eight was driving right down its own pioneered Earth-moon interstate, down the mathematical highway it must fly to reach a point 400,000 feet above Earth – the exact angle and altitude to reenter with a speed greater than any human had ever flown.
Two-and-a-half-days after leaving the moon, Earth’s gravity reached out and dragged Borman, Lovell, and Anders back into its atmosphere with Apollo-Eight becoming a man-made meteor.  Temperatures soared to those on the surfaces of stars – plunging downward the astronauts knew their lives depended on how well their ship had been built.
Apollo-Eight traded its speed for heat.  The hotter the fire flowing from the heat shield, the slower the spacecraft, and suddenly they were safely two miles above the Pacific, in sight of Christmas Island, and three large parachutes streamed away, blossoming wide and full.
The world cheered.
They returned to thundering ovations.
The road to the moon was open.