Genesis: The Story of Apollo 8 (12 page)

Read Genesis: The Story of Apollo 8 Online

Authors: Robert Zimmerman

Tags: #History, #United States, #20th Century, #test

 

Page 52
C.G. stands for "center of gravity."
path to the moon. "The damned S4B was uncomfortably close, its nose wandering within 500 feet."
2
Soon he was forced to turn the capsule away from the earth in order to keep watch on the booster.
Nor did he like how the S4B was venting fuel. "It's spewing out from all sides like a huge water sprinkler," he told the ground. "I believe we're going to have to vent or thrust away from this thing. We seem to be getting closer."
Moving away from the booster wasn't going to be as simple as Borman would have liked. The computers on the ground had calculated Apollo 8's heading, and determined that it was so accurate that the next mid-course correction was hardly needed. But mission control also wanted to fire the S.P.S. engine before the spacecraft got too far from earth. Like Borman's maneuvering controls, the S.P.S. was quite different from most earthbound engines, and was one of the reasons that NASA had gambled on sending Apollo 8 to the moon. The S.P.S. used hypergolic chemicals, meaning that when the fuel, a mixture of hydrazine and unsymmetrical dimethyl-hydrazine, made contact with the oxidizer, nitrogen tetroxide, the chemicals instantly ignited, producing thrust. No spark was needed. Without a complicated ignition system, the engine was simpler, and hopefully more reliable.
Two days before launch, however, engineers doing ground tests on another S.P.S. engine noticed an anomaly that posed a possible hazard. The engineers found that unless the combustion chamber of each new S.P.S. engine was primed, "wetted" with a small amount of fuel, there was a chance

 

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that the engine might explode the first time it was turned up to full thrust. The solution, not complicated, required giving the S.P.S. a single very short burst. The first mid-course correction, scheduled about eleven hours into the flight, would be the ideal opportunity to do this.
First, however, the ground engineers needed Borman to push the spacecraft a little bit more off course. The S.P.S. was too powerful an engine to make very small course corrections it would be like using a bomb to kill a fly. By doing a sideways burn now with the capsule's small attitude thrusters, the spacecraft's course would be changed enough so that several hours hence they could use the S.P.S. engine to correct it.
In order to change the spacecraft's course, however, Borman needed to reorient the capsule, putting the earth in the windows instead of the S4B booster. ''I don't want to do that," Borman explained. "I'll lose sight of the S4B." He and mission control compromised. The commander would position the spacecraft so that he could see both earth and booster, and make as much of a sideways burn as possible from this position.
Now however, Borman had to relocate the earth. For the next ten minutes he struggled, with Lovell's and Anders' help, to put both the earth and the booster in view. After five minutes Collins asked him if he had been able to do the burn. Borman responded, "As soon as we find the earth, we'll do it."
This brought a burst of startled laughter in Houston. It seemed absurd to say that the earth was hard to find.
Finally Borman was able to make the burn. He looked out his window at the S4B and reported, "We seem to be drifting away from this thing a little bit, although it is still pointing at us quite closer than I'd like."
Then he used the service module's side thrusters to put the module in what he called "barbecue mode," a slow roll spinning once per hour. This evenly distributed the burning heat of the sun over the entire surface of the spacecraft.
They had been in space for six hours, and awake for twelve. One by one the three men pulled off their bulky spacesuits so that they were dressed, not in street clothes, but in lightweight jumpsuits. Instead of magnetic-soled shoes, they wore cloth booties. And instead of "walking" from point to point, they simply pushed off one wall and floated across the cabin. Each man ate something, and things began to quiet down.

 

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For a variety of reasons, astronaut Pete Conrad had pinned the nickname "Shaky" on Jim Lovell.
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Though Jim
always
made things work in the end (like Borman and Anders, Lovell had never lost a plane in flight, and had finished ahead of Conrad in test pilot training), silly and sometimes life-threatening things seemed always to happen around him.
Shortly after reaching orbit, Lovell started to move from his couch to his navigation station in the lower equipment bay. As he did so he accidentally pulled on the toggle switch for his life vest, activating it. Suddenly he wearing two bulging and growing balloons in a space that gave him very little room to manuever.
Borman and Anders laughed. When Borman spoke to the ground, he described Lovell by saying that "we've got one full Mae West with us."
Since the vest was filled with carbon dioxide, deflating it would cause the excess CO
2
to saturate the filters for cleaning the capsule's atmosphere. And Lovell had to get rid of it if he was to do his work.
Lovell carefully glided to the urine dump. Normally an astronaut would insert his personal plumbing into a hose and void his liquid waste into the great emptiness of space. Now Lovell inserted the hose into his life vest, squeezing the carbon dioxide gas through it and out of the capsule.
Soon he no longer resembled a big-breasted Hollywood star, and could store his spacesuit with the others.
With Borman steering and Anders alternating between taking photos and monitoring the capsule's operations, Lovell now got busy doing his main task, trying to prove that a human being could pinpoint his position in space without the use of ground-based help.
With the spacecraft's navigational telescope and sextant, Lovell sighted on several stars as well as the horizon of the earth, using this data to triangulate the spacecraft's course and position. This manual navigation system had been designed as a backup to ground-based calculations. Should communications fail, the astronauts would then use Lovell's sightings to program their course changes by hand.
Called the inertial measuring unit (or I.M.U.), this equipment tracked the spacecraft's orientation relative to the earth and solar system. Because space has no up and down or horizon line, the astronauts needed some other reference for pointing the spacecraft's nose and engines in the right direction.

 

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Set on three gimbals, one for each of the three dimensions, the I.M.U. was held stable by gyroscopes. Beginning from its initial setting on the launchpad, the unit recorded any changes thereafter of the capsule's orientaton. These changes in turn were reflected by a control panel indicator the astronauts called the eight ball, a grapefruit-sized sphere incised with the sky's longitudes and latitudes. As the capsule pitched, rolled, or yawed relative to the stars, the I.M.U. told the eight ball to turn and roll correspondingly.
Originally NASA had planned to shut the I.M.U. off when not in use in order to conserve power, and let Lovell re-set it manually prior to each burn. Borman and the other astronauts disagreed vigorously with this idea. As Borman wrote later, "Experience had taught me that when you have something running perfectly, particularly a mechanical or electrical device, it's best to leave it alone."
4
After much discussion the engineers agreed. The I.M.U. was left on for the entire flight, with Lovell's sightings used merely for back-up.
This decision seemed even wiser now, only a few hours from earth. While still in orbit Lovell had found it difficult to locate any stars because of the planet's glare. Now, on the way to the moon, the venting from the S4B booster was making star identification tricky. The fuel scattered into millions of tiny frozen globules, and the light reflected off these particles to fill the void around them with many "pseudo-stars."
Nonetheless, Lovell made an attempt at pinpointing his location, and radioed his results back to earth. There, ground controllers compared his results with their own to see how accurate the figures were.
Accuracy was essential. Not only were the astronauts traveling farther than anyone ever had at a greater speed, but the elements that made up their motion were exceedingly complex. The spacecraft had left a planet whose surface was moving at about 1,000 miles per hour as the globe rotated. That planet was also cruising through space at 67,000 miles per hour. The spacecraft was aimed at a moon moving at 2,300 miles an hour relative to the earth, with an orbital plane that differed from the spacecraft's. Each of these vectors had to be incorporated into both Lovell's and the ground engineers' calculations so that they could aim Apollo 8 not at where the moon was, but at a point in space it would reach three days hence. And their calculations had to be accurate within four ten-thousandth of a single percentage point.

 

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The S4B third stage, surrounded by pseudo-stars.
This was not unlike a person jumping from a speeding roller coaster car and trying to catch a bullet shot past them as they fell.
About ten hours into the flight, Mike Collins's shift ended and he was replaced at communications by Ken Mattingly. Mattingly had joined NASA in April 1966 as part of the fourth class of astronauts. Addicted to flying, he had spent his life in the Navy finding ways to get himself in the air. Now he was on the Apollo 8 support team, handling radio communications with a spacecraft almost 60,000 miles from home. To Mattingly this seemed an exhilarating turn of events.
He now radioed that he had the numbers for the first mid-course correction, scheduled for one hour hence. Borman, still at the controls, told him he was ready to take them down.
This aspect of early space exploration should horrify a modern computer user. Apollo 8's on-board computer was not capable of doing the calculations necessary for each planned rocket firing. Nor was its programmable memory of

 

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approximately four kilobytes (about eight to thirty thousand times smaller than today's average desktop) large enough to store much data.
5
The ground computers did the calculations, and then mission control verbally passed the numbers up to the astronauts. They in turn then manually entered this data into the computer, which in turn controled the automatic firing of the spacecraft's engines.
Passing the numbers up from the ground, however, was hardly a simple task. Consider the list of numbers that Ken Mattingly now radioed to Frank Borman for mid-course correction number one: "Okay. Sixty-three thousand, one hundred and forty minus one sixty-three, plus one twenty-nine zero thirteen fifty-six forty-eight ninety-seven, minus zero zero five, ninety-nine, plus zero zero zero zero zero, plus four seven zero one six, one seventy-seven one forty-three zero zero zero November Alpha, plus zero zero one ninety-seven forty-seven zero twenty-five fifty-one four sixty-eight eighteen twelve twelve eighty-three two fifty-seven zero twenty-three."
He took a breath, then continued. "Up two sixty-three, left seventeen, plus eleven ninety-five, minus one sixty-five zero zero one twenty-six eighty-three three fifty-six zero eight zero fifty forty-seven zero five, north stars, zero sixty-eight zero ninety-seven three fifty-six, no ullage."
Borman, who was writing this litany down as he heard it, now repeated it back to Mattingly, confirming that he got it right. Later, Jim Lovell entered the numbers into the on-board computer, which would then be programmed to fire the rockets when scheduled.
An hour later and eleven hours into the flight, the computer did exactly that. As commanded, the S.P.S. engine fired, burping for just over two seconds. Not only did this blast successfully prime the S.P.S. engine, it was so accurate that it made the next two course corrections unnecessary. Mission control decided that Apollo 8 could continue on its course to the moon, still three days away.
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Valerie Anders was practically a prisoner in her own home. The mob of reporters on her front lawn had grown so large that she didn't dare go outside. To her chagrin

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