The Apollo 8 spacecraft streaked manfully through the heavens at a mile per second, picking up speed rapidly as it approached the Moon. Astronauts Frank Borman, Jim Lovell and Bill Anders could feel no sense of speed nor acceleration but they knew their velocity would soon be a problem if they didnt do something to slow down.
Their Command/Service Module was about 5000 nautical miles from the lunar surface and already under the Moons gravitational influence. They were unaware of its proximity because for some time they had not been able to see it through the window. They were heading into orbit backwards and awaiting the final calculations from Mission Control for firing the main SPS rocket. In Houston, the greatest minds in American space flight had been crunching numbers on the lunar orbit insertion, or LOI. Astronaut Jerry Carr was taking his turn at the capsule communicator console and called on the crew of Apollo 8 to check the maths.
Apollo 8, Houston; with a preliminary LOI-1 PAD. Over.
Lovell answered. Roger. Stand by one.
Roger. Standing by, capcom confirmed.
There was a long pause while Lovell readied himself to take the numbers. There would be no going at it half-cocked.
Houston, Apollo 8. Ready to copy.
Apollo 8, this is Houston. Roger. LOI-1 SPS/G&N 62844, minus 1 point 61, plus 1 point 29, 069:08:19.05. Copy?
Eight is copying, Lovell answered.
The numbers kept coming in a long line. Every digit needed to be right for the astronauts to execute a precisely synchronised rendezvous with the Moon, which itself was travelling through space at more than 3000 feet per second.
Houston had Apollo 8 lighting the candle at flight time 69 hours, eight minutes and 19 seconds. The burn had to last for precisely four minutes and two seconds. If the engine didnt fire, their trajectory would become their fail-safe mechanism, bringing the spacecraft close enough to allow the Moons gravity to sling-shot them around and back toward Earth. If the burn was too long (meaning they couldnt shut the engine down) the rapid loss of velocity would send them crashing into the Moon. If the engine cut out too soon and couldnt be restarted, their command module would enter an elliptical orbit that would gradually decay under the counter influence of the Earths gravitational field and eventually catapult them into outer space.
Apollo 8 this is Houston. At 68:04 youre go for LOI.
OK, Apollo 8 is go, said Borman.
Youre riding the best bird we can find, said capcom.
An hour later they said their farewells as they approached the far side of the Moon for the first time. Their velocity had increased to about 1.5 miles per second and was continuing to build rapidly. Strong emotions arose within each of the men in the capsule as they approached LOS loss of signal.
Thanks a lot troops, well see you on the other side, Anders told Mission Control.
Much to Commander Bormans amazement, the Earth disappeared from view at precisely the moment stated in their mission schedule.
They were all alone. So far so good. Borman gazed briefly out of the window into the blackness. Back home it would soon be Christmas Eve.
NASA had given them the greatest Christmas gift ever a trip to the Moon. They were right alongside it now, but for the moment the lunar night rendered the surface almost invisible. He strained for a sign of the lunar horizon the sunset terminator hoping to cross-check the ships attitude.
On that horizon, boy, I cant see squat out there, said Borman.
You want us to turn off your lights to check it? Anders asked.
Lovell saw it first. Hey, I got the Moon.
Do you? asked Anders.
Right below us.
Oh my God!
The response alarmed Borman. Whats wrong?
Look at that! Anders called in astonishment. He was just admiring the view.
Borman was still nervous. Well, come on lets whats, whats the
69.06, Lovell replied, knowing LOI ignition time remained Bormans primary concern.
Stand by, were all set, Borman replied. 2:13, 2:12
Just over two minutes to LOI.
But moments later Anders and Lovell were at it again, unable to restrain themselves from gazing out the window like space tourists. Borman had to marvel that years of training and simulation had utterly failed to prepare them for the toe-curling awe of the real thing. For all of human history it had been but a thumbnail smudge in the sky and boy oh boy look at it now. But he didnt want to think about it just yet. There was too much to do before they could relax.
All right, all right, come on. Youre going to look at that for a long time, he told them.
A handful of seconds later they fired the engine to start the longest four minutes of their lives.
Everythings good over here so far, Borman called.
Everything is looking good, Anders confirmed.
In the stress of the moment it felt like time was slowing down. They were performing a task requiring a high degree of accuracy using equipment that had never before been put to the test so far from Earth. Catastrophic system failure was always a distinct possibility and halfway through the burn the tension was palpable.
Yknow, it seems like about three gees, Anders remarked.
A problem emerged about three minutes in. Apollos onboard computer told them thrust was two percent below optimal. They would have to burn a little longer to compensate, but it would be OK.
Finally Borman heard himself call out: Shutdown.
They successfully shut down the SPS and Apollo 8 was in an elliptical lunar orbit that took them as close as 60 nautical miles above the surface.
From Earth, the Moon was a crescent in the sky. This meant most of the far side (forever invisible from humanity) was illuminated in sunlight. It was an important consideration for the astronauts when they disappeared from the Earths view. They wouldnt be in the dark for long.
From here on, their focus could shift to the one thing everyone was dying to take a close look at. Borman set the ship to rotate at precisely the right pace to keep the windows permanently pointed at the lunar surface. This created a strange effect. Because they were weightless, the notion of up and down had become almost meaningless. Their minds naturally adopted the interior of the capsule as the only frame of reference. That meant they felt as if they were alongside the Moon rather than above it.
Anders and Lovell began to set up the Hasselblad cameras to record what they saw. The surface wasnt completely foreign it had been photographed by a Russian satellite and NASA had acquired the imagery from the signal transmitted by the commie Lunar Orbiter. Seeing it for real beat the hell out of a few hazy satellite images. And back on Earth their photographs would offer far higher resolution for the boffins to examine in detail.
Although Bormann had faith and confidence in both NASA and the brilliant minds who had designed and built their spacecraft, it was nevertheless a great relief the first time they saw the Earth come back into view.
The familiar voice of Jerry Carr filled their headsets.
Apollo 8, Houston. Over.
The slightly uncertain lilt in old Jerrys tone gave little away to the casual listener but it told Borman capcom had been getting a tad anxious. No doubt he had been calling them for some time without a response. Lovell put him out of his misery. Go ahead, Houston. This is Apollo 8. Burn complete. Our orbit is 169.1 by 60.5.
Apollo 8, this is Houston. Roger. 169.1 by 60.5.
As the astronauts passed over the Moons more familiar face they began to search for places where future Apollo missions might land. There were plenty of options. The Sea of Tranquillity was a strong possibility. Its gentle undulation looked positively inviting compared to the messed-up havoc of the far side. The face of the Moon forever pointed toward outer space almost felt like its hidden shame; craters upon craters, much more densely packed than they were on the near side. It was the result of a far greater frequency of impact from the relentless hailstorm of ice and rock from the asteroid belt and beyond battering its surface. The Moons near side was protected because it permanently faced the Earth due to the gravitational interaction known as tidal locking.