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Sunday, December 2, 2018

Reading List: Apollo 8

Kluger, Jeffrey. Apollo 8. New York: Picador, 2017. ISBN 978-1-250-18251-7.
As the tumultuous year 1968 drew to a close, NASA faced a serious problem with the Apollo project. The Apollo missions had been carefully planned to test the Saturn V booster rocket and spacecraft (Command/Service Module [CSM] and Lunar Module [LM]) in a series of increasingly ambitious missions, first in low Earth orbit (where an immediate return to Earth was possible in case of problems), then in an elliptical Earth orbit which would exercise the on-board guidance and navigation systems, followed by lunar orbit, and finally proceeding to the first manned lunar landing. The Saturn V had been tested in two unmanned “A” missions: Apollo 4 in November 1967 and Apollo 6 in April 1968. Apollo 5 was a “B” mission, launched on a smaller Saturn 1B booster in January 1968, to test an unmanned early model of the Lunar Module in low Earth orbit, primarily to verify the operation of its engines and separation of the descent and ascent stages. Apollo 7, launched in October 1968 on a Saturn 1B, was the first manned flight of the Command and Service modules and tested them in low Earth orbit for almost 11 days in a “C” mission.

Apollo 8 was planned to be the “D” mission, in which the Saturn V, in its first manned flight, would launch the Command/Service and Lunar modules into low Earth orbit, where the crew, commanded by Gemini veteran James McDivitt, would simulate the maneuvers of a lunar landing mission closer to home. McDivitt's crew was trained and ready to go in December 1968. Unfortunately, the lunar module wasn't. The lunar module scheduled for Apollo 8, LM-3, had been delivered to the Kennedy Space Center in June of 1968, but was, to put things mildly, a mess. Testing at the Cape discovered more than a hundred serious defects, and by August it was clear that there was no way LM-3 would be ready for a flight in 1968. In fact, it would probably slip to February or March 1969. This, in turn, would push the planned “E” mission, for which the crew of commander Frank Borman, command module pilot James Lovell, and lunar module pilot William Anders were training, aimed at testing the Command/Service and Lunar modules in an elliptical Earth orbit venturing as far as 7400 km from the planet and originally planned for March 1969, three months later, to June, delaying all subsequent planned missions and placing the goal of landing before the end of 1969 at risk.

But NASA were not just racing the clock—they were also racing the Soviet Union. Unlike Apollo, the Soviet space program was highly secretive and NASA had to go on whatever scraps of information they could glean from Soviet publications, the intelligence community, and independent tracking of Soviet launches and spacecraft in flight. There were, in fact, two Soviet manned lunar programmes running in parallel. The first, internally called the Soyuz 7K-L1 but dubbed “Zond” for public consumption, used a modified version of the Soyuz spacecraft launched on a Proton booster and was intended to carry two cosmonauts on a fly-by mission around the Moon. The craft would fly out to the Moon, use its gravity to swing around the far side, and return to Earth. The Zond lacked the propulsion capability to enter lunar orbit. Still, success would allow the Soviets to claim the milestone of first manned mission to the Moon. In September 1968 Zond 5 successfully followed this mission profile and safely returned a crew cabin containing tortoises, mealworms, flies, and plants to Earth after their loop around the Moon. A U.S. Navy destroyer observed recovery of the re-entry capsule in the Indian Ocean. Clearly, this was preparation for a manned mission which might occur on any lunar launch window.

(The Soviet manned lunar landing project was actually far behind Apollo, and would not launch its N1 booster on that first, disastrous, test flight until February 1969. But NASA did not know this in 1968.) Every slip in the Apollo program increased the probability of its being scooped so close to the finish line by a successful Zond flyby mission.

These were the circumstances in August 1968 when what amounted to a cabal of senior NASA managers including George Low, Chris Kraft, Bob Gilruth, and later joined by Wernher von Braun and chief astronaut Deke Slayton, began working on an alternative. They plotted in secret, beneath the radar and unbeknownst to NASA administrator Jim Webb and his deputy for manned space flight, George Mueller, who were both out of the country, attending an international conference in Vienna. What they were proposing was breathtaking in its ambition and risk. They envisioned taking Frank Borman's crew, originally scheduled for Apollo 9, and putting them into an accelerated training program to launch on the Saturn V and Apollo spacecraft currently scheduled for Apollo 8. They would launch without a Lunar Module, and hence be unable to land on the Moon or test that spacecraft. The original idea was to perform a Zond-like flyby, but this was quickly revised to include going into orbit around the Moon, just as a landing mission would do. This would allow retiring the risk of many aspects of the full landing mission much earlier in the program than originally scheduled, and would also allow collection of precision data on the lunar gravitational field and high resolution photography of candidate landing sites to aid in planning subsequent missions. The lunar orbital mission would accomplish all the goals of the originally planned “E” mission and more, allowing that mission to be cancelled and therefore not requiring an additional booster and spacecraft.

But could it be done? There were a multitude of requirements, all daunting. Borman's crew, training toward a launch in early 1969 on an Earth orbit mission, would have to complete training for the first lunar mission in just sixteen weeks. The Saturn V booster, which suffered multiple near-catastrophic engine failures in its second flight on Apollo 6, would have to be cleared for its first manned flight. Software for the on-board guidance computer and for Mission Control would have to be written, tested, debugged, and certified for a lunar mission many months earlier than previously scheduled. A flight plan for the lunar orbital mission would have to be written from scratch and then tested and trained in simulations with Mission Control and the astronauts in the loop. The decision to fly Borman's crew instead of McDivitt's was to avoid wasting the extensive training the latter crew had undergone in LM systems and operations by assigning them to a mission without an LM. McDivitt concurred with this choice: while it might be nice to be among the first humans to see the far side of the Moon with his own eyes, for a test pilot the highest responsibility and honour is to command the first flight of a new vehicle (the LM), and he would rather skip the Moon mission and fly later than lose that opportunity. If the plan were approved, Apollo 8 would become the lunar orbit mission and the Earth orbit test of the LM would be re-designated Apollo 9 and fly whenever the LM was ready.

While a successful lunar orbital mission on Apollo 8 would demonstrate many aspects of a full lunar landing mission, it would also involve formidable risks. The Saturn V, making only its third flight, was coming off a very bad outing in Apollo 6 whose failures might have injured the crew, damaged the spacecraft hardware, and precluded a successful mission to the Moon. While fixes for each of these problems had been implemented, they had never been tested in flight, and there was always the possibility of new problems not previously seen.

The Apollo Command and Service modules, which would take them to the Moon, had not yet flown a manned mission and would not until Apollo 7, scheduled for October 1968. Even if Apollo 7 were a complete success (which was considered a prerequisite for proceeding), Apollo 8 would be only the second manned flight of the Apollo spacecraft, and the crew would have to rely upon the functioning of its power generation, propulsion, and life support systems for a mission lasting six days. Unlike an Earth orbit mission, if something goes wrong en route to or returning from the Moon, you can't just come home immediately. The Service Propulsion System on the Service Module would have to work perfectly when leaving lunar orbit or the crew would be marooned forever or crash on the Moon. It would only have been tested previously in one manned mission and there was no backup (although the single engine did incorporate substantial redundancy in its design).

The spacecraft guidance, navigation, and control system and its Apollo Guidance Computer hardware and software, upon which the crew would have to rely to navigate to and from the Moon, including the critical engine burns to enter and leave lunar orbit while behind the Moon and out of touch with Mission Control, had never been tested beyond Earth orbit.

The mission would go to the Moon without a Lunar Module. If a problem developed en route to the Moon which disabled the Service Module (as would happen to Apollo 13 in April 1970), there would be no LM to serve as a lifeboat and the crew would be doomed.

When the high-ranking conspirators presented their audacious plan to their bosses, the reaction was immediate. Manned spaceflight chief Mueller immediately said, “Can't do that! That's craziness!” His boss, administrator James Webb, said “You try to change the entire direction of the program while I'm out of the country?” Mutiny is a strong word, but this seemed to verge upon it. Still, Webb and Mueller agreed to meet with the lunar cabal in Houston on August 22. After a contentious meeting, Webb agreed to proceed with the plan and to present it to President Johnson, who was almost certain to approve it, having great confidence in Webb's management of NASA. The mission was on.

It was only then that Borman and his crewmembers Lovell and Anders learned of their reassignment. While Anders was disappointed at the prospect of being the Lunar Module Pilot on a mission with no Lunar Module, the prospect of being on the first flight to the Moon and entrusted with observation and photography of lunar landing sites more than made up for it. They plunged into an accelerated training program to get ready for the mission.

NASA approached the mission with its usual “can-do” approach and public confidence, but everybody involved was acutely aware of the risks that were being taken. Susan Borman, Frank's wife, privately asked Chris Kraft, director of Flight Operations and part of the group who advocated sending Apollo 8 to the Moon, with a reputation as a plain-talking straight shooter, “I really want to know what you think their chances are of coming home.” Kraft responded, “You really mean that, don't you?” “Yes,” she replied, “and you know I do.” Kraft answered, “Okay. How's fifty-fifty?” Those within the circle, including the crew, knew what they were biting off.

The launch was scheduled for December 21, 1968. Everybody would be working through Christmas, including the twelve ships and thousands of sailors in the recovery fleet, but lunar launch windows are set by the constraints of celestial mechanics, not human holidays. In November, the Soviets had flown Zond 6, and it had demonstrated the “double dip” re-entry trajectory required for human lunar missions. There were two system failures which killed the animal test subjects on board, but these were covered up and the mission heralded as a great success. From what NASA knew, it was entirely possible the next launch would be with cosmonauts bound for the Moon.

Space launches were exceptional public events in the 1960s, and the first flight of men to the Moon, just about a hundred years after Jules Verne envisioned three men setting out for the Moon from central Florida in a “cylindro-conical projectile” in De la terre à la lune (From the Earth to the Moon), similarly engaging the world, the launch of Apollo 8 attracted around a quarter of a million people to watch the spectacle in person and hundreds of millions watching on television both in North America and around the globe, thanks to the newfangled technology of communication satellites. Let's tune in to CBS television and relive this singular event with Walter Cronkite.

CBS coverage of the Apollo 8 launch

Now we step inside Mission Control and listen in on the Flight Director's audio loop during the launch, illustrated with imagery and simulations.

The Saturn V performed almost flawlessly. During the second stage burn mild pogo oscillations began but, rather than progressing to the point where they almost tore the rocket apart as had happened on the previous Saturn V launch, von Braun's team's fixes kicked in and seconds later Borman reported, “Pogo's damping out.” A few minutes later Apollo 8 was in Earth orbit.

Jim Lovell had sixteen days of spaceflight experience across two Gemini missions, one of them Gemini 7 where he endured almost two weeks in orbit with Frank Borman. Bill Anders was a rookie, on his first space flight. Now weightless, all three were experiencing a spacecraft nothing like the cramped Mercury and Gemini capsules which you put on as much as boarded. The Apollo command module had an interior volume of six cubic metres (218 cubic feet, in the quaint way NASA reckons things) which may not seem like much for a crew of three, but in weightlessness, with every bit of space accessible and usable, felt quite roomy. There were five real windows, not the tiny portholes of Gemini, and plenty of space to move from one to another.

With all this roominess and mobility came potential hazards, some verging on slapstick, but, in space, serious nonetheless. NASA safety personnel had required the astronauts to wear life vests over their space suits during the launch just in case the Saturn V malfunctioned and they ended up in the ocean. While moving around the cabin to get to the navigation station after reaching orbit, Lovell, who like the others hadn't yet removed his life vest, snagged its activation tab on a strut within the cabin and it instantly inflated. Lovell looked ridiculous and the situation comical, but it was no laughing matter. The life vests were inflated with carbon dioxide which, if released in the cabin, would pollute their breathing air and removal would use up part of a CO₂ scrubber cartridge, of which they had a limited supply on board. Lovell finally figured out what to do. After being helped out of the vest, he took it down to the urine dump station in the lower equipment bay and vented it into a reservoir which could be dumped out into space. One problem solved, but in space you never know what the next surprise might be.

The astronauts wouldn't have much time to admire the Earth through those big windows. Over Australia, just short of three hours after launch, they would re-light the engine on the third stage of the Saturn V for the “trans-lunar injection” (TLI) burn of 318 seconds, which would accelerate the spacecraft to just slightly less than escape velocity, raising its apogee so it would be captured by the Moon's gravity. After housekeeping (presumably including the rest of the crew taking off those pesky life jackets, since there weren't any wet oceans where they were going) and reconfiguring the spacecraft and its computer for the maneuver, they got the call from Houston, “You are go for TLI.” They were bound for the Moon.

The third stage, which had failed to re-light on its last outing, worked as advertised this time, with a flawless burn. Its job was done; from here on the astronauts and spacecraft were on their own. The booster had placed them on a free-return trajectory. If they did nothing (apart from minor “trajectory correction maneuvers” easily accomplished by the spacecraft's thrusters) they would fly out to the Moon, swing around its far side, and use its gravity to slingshot back to the Earth (as Lovell would do two years later when he commanded Apollo 13, although there the crew had to use the engine of the LM to get back onto a free-return trajectory after the accident).

Apollo 8 rapidly climbed out of the Earth's gravity well, trading speed for altitude, and before long the astronauts beheld a spectacle no human eyes had glimpsed before: an entire hemisphere of Earth at once, floating in the inky black void. On board, there were other concerns: Frank Borman was puking his guts out and having difficulties with the other end of the tubing as well. Borman had logged more than six thousand flight hours in his career as a fighter and test pilot, most of it in high-performance jet aircraft, and fourteen days in space on Gemini 7 without any motion sickness. Many people feel queasy when they experience weightlessness the first time, but this was something entirely different and new in the American space program. And it was very worrisome. The astronauts discussed the problem on private tapes they could downlink to Mission Control without broadcasting to the public, and when NASA got around to playing the tapes, the chief flight surgeon, Dr. Charles Berry, became alarmed.

As he saw it, there were three possibilities: motion sickness, a virus of some kind, or radiation sickness. On its way to the Moon, Apollo 8 passed directly through the Van Allen radiation belts, spending two hours in this high radiation environment, the first humans to do so. The total radiation dose was estimated as roughly the same as one would receive from a chest X-ray, but the composition of the radiation was different and the exposure was over an extended time, so nobody could be sure it was safe. The fact that Lovell and Anders had experienced no symptoms argued against the radiation explanation. Berry concluded that a virus was the most probable cause and, based upon the mission rules said, “I'm recommending that we consider canceling the mission.” The risk of proceeding with the commander unable to keep food down and possibly carrying a virus which the other astronauts might contract was too great in his opinion. This recommendation was passed up to the crew. Borman, usually calm and collected even by astronaut standards, exclaimed, “What? That is pure, unadulterated horseshit.” The mission would proceed, and within a day his stomach had settled.

This was the first case of space adaptation syndrome to afflict an American astronaut. (Apparently some Soviet cosmonauts had been affected, but this was covered up to preserve their image as invincible exemplars of the New Soviet Man.) It is now known to affect around a third of people experiencing weightlessness in environments large enough to move around, and spontaneously clears up in two to four (miserable) days.

The two most dramatic and critical events in Apollo 8's voyage would occur on the far side of the Moon, with 3500 km of rock between the spacecraft and the Earth totally cutting off all communications. The crew would be on their own, aided by the computer and guidance system and calculations performed on the Earth and sent up before passing behind the Moon. The first would be lunar orbit insertion (LOI), scheduled for 69 hours and 8 minutes after launch. The big Service Propulsion System (SPS) engine (it was so big—twice as large as required for Apollo missions as flown—because it was designed to be able to launch the entire Apollo spacecraft from the Moon if a “direct ascent” mission mode had been selected) would burn for exactly four minutes and seven seconds to bend the spacecraft's trajectory around the Moon into a closed orbit around that world.

If the SPS failed to fire for the LOI burn, it would be a huge disappointment but survivable. Apollo 8 would simply continue on its free-return trajectory, swing around the Moon, and fall back to Earth where it would perform a normal re-entry and splashdown. But if the engine fired and cut off too soon, the spacecraft would be placed into an orbit which would not return them to Earth, marooning the crew in space to die when their supplies ran out. If it burned just a little too long, the spacecraft's trajectory would intersect the surface of the Moon—lithobraking is no way to land on the Moon.

When the SPS engine shut down precisely on time and the computer confirmed the velocity change of the burn and orbital parameters, the three astronauts were elated, but they were the only people in the solar system aware of the success. Apollo 8 was still behind the Moon, cut off from communications. The first clue Mission Control would have of the success or failure of the burn would be when Apollo 8's telemetry signal was reacquired as it swung around the limb of the Moon. If too early, it meant the burn had failed and the spacecraft was coming back to Earth; that moment passed with no signal. Now tension mounted as the clock ticked off the seconds to the time expected for a successful burn. If that time came and went with no word from Apollo 8, it would be a really bad day. Just on time, the telemetry signal locked up and Jim Lovell reported, “Go ahead, Houston, this is Apollo 8. Burn complete. Our orbit 160.9 by 60.5.” (Lovell was using NASA's preferred measure of nautical miles; in proper units it was 311 by 112 km. The orbit would subsequently be circularised by another SPS burn to 112.7 by 114.7 km.) The Mission Control room erupted into an un-NASA-like pandemonium of cheering.

Apollo 8 would orbit the Moon ten times, spending twenty hours in a retrograde orbit with an inclination of 12 degrees to the lunar equator, which would allow it to perform high-resolution photography of candidate sites for early landing missions under lighting conditions similar to those expected at the time of landing. In addition, precision tracking of the spacecraft's trajectory in lunar orbit would allow mapping of the Moon's gravitational field, including the “mascons” which perturb the orbits of objects in low lunar orbits and would be important for longer duration Apollo orbital missions in the future.

During the mission, the crew were treated to amazing sights and, in particular, the dramatic difference between the near side, with its many flat “seas”, and the rugged highlands of the far side. Coming around the Moon they saw the spectacle of earthrise for the first time and, hastily grabbing a magazine of colour film and setting aside the planned photography schedule, Bill Anders snapped the photo of the Earth rising above the lunar horizon which became one of the most iconic photographs of the twentieth century. Here is a reconstruction of the moment that photo was taken.

On the ninth and next-to-last orbit, the crew conducted a second television transmission which was broadcast worldwide. It was Christmas Eve on much of the Earth, and, coming at the end of the chaotic, turbulent, and often tragic year of 1968, it was a magical event, remembered fondly by almost everybody who witnessed it and felt pride for what the human species had just accomplished.

You have probably heard this broadcast from the Moon, often with the audio overlaid on imagery of the Moon from later missions, with much higher resolution than was actually seen in that broadcast. Here, in three parts, is what people, including this scrivener, actually saw on their televisions that enchanted night. The famous reading from Genesis is in the third part. This description is eerily similar to that in Jules Verne's 1870 Autour de la lune.

After the end of the broadcast, it was time to prepare for the next and absolutely crucial maneuver, also performed on the far side of the Moon: trans-Earth injection, or TEI. This would boost the spacecraft out of lunar orbit and send it back on a trajectory to Earth. This time the SPS engine had to work, and perfectly. If it failed to fire, the crew would be trapped in orbit around the Moon with no hope of rescue. If it cut off too soon or burned too long, or the spacecraft was pointed in the wrong direction when it fired, Apollo 8 would miss the Earth and orbit forever far from its home planet or come in too steep and burn up when it hit the atmosphere. Once again the tension rose to a high pitch in Mission Control as the clock counted down to the two fateful times: this time they'd hear from the spacecraft earlier if it was on its way home and later or not at all if things had gone tragically awry. Exactly when expected, the telemetry screens came to life and a second later Jim Lovell called, “Houston, Apollo 8. Please be informed there is a Santa Claus.”

Now it was just a matter of falling the 375,000 kilometres from the Moon, hitting the precise re-entry corridor in the Earth's atmosphere, executing the intricate “double dip” re-entry trajectory, and splashing down near the aircraft carrier which would retrieve the Command Module and crew. Earlier unmanned tests gave confidence it would all work, but this was the first time men would be trying it.

There was some unexpected and embarrassing excitement on the way home. Mission Control had called up a new set of co-ordinates for the “barbecue roll” which the spacecraft executed to even out temperature. Lovell was asked to enter “verb 3723, noun 501” into the computer. But, weary and short on sleep, he fat-fingered the commands and entered “verb 37, noun 01”. This told the computer the spacecraft was back on the launch pad, pointing straight up, and it immediately slewed to what it thought was that orientation. Lovell quickly figured out what he'd done, “It was my goof”, but by this time he'd “lost the platform”: the stable reference the guidance system used to determine in which direction the spacecraft was pointing in space. He had to perform a manual alignment, taking sightings on a number of stars, to recover the correct orientation of the stable platform. This was completely unplanned but, as it happens, in doing so Lovell acquired experience that would prove valuable when he had to perform the same operation in much more dire circumstances on Apollo 13 after an explosion disabled the computer and guidance system in the Command Module. Here is the author of the book, Jeffrey Kluger, discussing Jim Lovell's goof.

The re-entry went completely as planned, flown entirely under computer control, with the spacecraft splashing into the Pacific Ocean just 6 km from the aircraft carrier Yorktown. But because the splashdown occurred before dawn, it was decided to wait until the sky brightened to recover the crew and spacecraft. Forty-three minutes after splashdown, divers from the Yorktown arrived at the scene, and forty-five minutes after that the crew was back on the ship. Apollo 8 was over, a total success. This milestone in the space race had been won definitively by the U.S., and shortly thereafter the Soviets abandoned their Zond circumlunar project, judging it an anticlimax and admission of defeat to fly by the Moon after the Americans had already successfully orbited it.

This is the official NASA contemporary documentary about Apollo 8.

Here is an evening with the Apollo 8 astronauts recorded at the National Air and Space Museum on 2008-11-13 to commemorate the fortieth anniversary of the flight.

This is a reunion of the Apollo 8 astronauts on 2009-04-23.

As of this writing, all of the crew of Apollo 8 are alive, and, in a business where divorce was common, remain married to the women they wed as young military officers.

Posted at December 2, 2018 15:28