Category How Apollo Flew to the Moon

It is hardly surprising that the Apollo programme, which was lauded as one of humanity’s greatest achievements, should have spawned a vibrant niche in publishing. In the wake of the missions, innumerable books commemorated the flights of the Apollo crews as publishers took advantage of the public’s interest. But then, within ten years, the story was held to be less fascinating and new books on Apollo became increasingly rare.

Things began to change, however, beginning with the twentieth anniversary of the first manned landing on the Moon in 1969. A generation who had watched Apollo on their parents’ television screens with wide-eyed wonder had grown up and taken the reins of society. To them and those w’ho were born after the landings, the programme became the product of the previous generation and. at this point, retrospectives began to appear. Apollo is now written as history rather than as current events. However, much that has become available concentrates on the programme’s conception and on those who transformed it from engineers’ dreams into a superpower’s goals. A particularly popular sub-niche is the astronaut biography, a somewhat variable collection of tomes that do much to relate the story of humanity’s only foray away from the grip of planet Earth. Other volumes relate, in varying levels of detail, what the intrepid explorers actually did during their far too brief spells on the surface of another world.

Remarkably few’ books discuss the practical aspects of how the voyage from the Earth to the Moon was achieved. The genre seldom describes the equipment that was used; nor does it relate the procedures and techniques that allowed the Apollo crews to accomplish their audacious task: in general, historians are not concerned with how a feat was achieved technically. Instead. Apollo’s written history comes in three dominant types: (I) the experiences and interrelationships of the people involved, (2) the political and social milieu in which they operated and (3) the polemic and ranting of those who arc doing the commentating. This is all well and good – to a point. The same applies to the modern media. The details of how something was achieved are considered to be the realm of the ‘geek’ or ‘nerd’, and the general public are thought, at best, to be disinterested in science and engineering, or at worst, incapable of understanding such rigorous topics.

One particularly thoughtful television programme of the late twentieth century looked at the conflict between reporting as the dissemination of facts, and reporting as the telling of human interest stories. Produced by actor Tom Ilanks, the series From the Earth to the Moon bravely dramatised the entire sweep of the Apollo programme and included an episode about the flight of Apollo 13, a mission that has become a byword for human doggedness and ingenuity in the face of overwhelming challenges. Rather than remake a story that had been well told in an earlier cinema release, the writers concocted a battle of wills between two characters – an older journalist who took the trouble read up on the technicalities and complexities of the mission and who cleverly and clearly did his level best to explain them to the public; and a young, upstart reporter whose mantra was human interest and who would not be seen reading the spacecraft’s checklist or NASA’s official press kit. A line from the upstart makes the case for the modern view. ‘‘You think America wants to know about PC burns and passive thermal rolls? That’s not news. man. That is ’Sominex’.” Somincx is a sleeping pill. He perceived an America that neither understood nor cared about science and had little interest in engineering niceties. What they wanted to read about was the emotional state of the families of the stricken astronauts.

But in the age of the internet, this uninformed public is swimming in an ocean of information, much of which is of dubious accuracy. Among this deluge of ideas is one that tests their understanding of historical truth. In recent years, whether for financial gain or just as a pseudo-intellectual prank, people have taken to questioning the veracity of Apollo’s greatest achievement. Websites abound that mock the very idea of America having achieved moonlandings in the 1960s and 1970s. They pick spurious holes in the historical record and rely on the ignorance of the public at large, feeding on a distrust of big government in order to sell books and TV to a section of society that savours and favours mammoth conspiracy theories.

The fact that one of the best documented events of history could be considered to be a hoax thrives partly because so few people actually know how the feat was achieved, or how the most basic laws of physics express themselves beyond the surface of our planet. I once spoke with a head teacher – an educated man in charge of over a thousand teenage pupils – who could quote Shakespeare as knowledgeably as he could discuss football. I asked him why the crews on board the Space Shuttle were seen to float about the cabin. “Because there’s no gravity in space, of course.’’ was the reply. At the time. I didn’t have the heart to enquire of him what kept the Moon in its orbit around Barth. I wasn’t trying to mock him but I wanted to understand the extent to which concepts derived from basic science were understood by the public. I soon learned that ignorance in science and engineering appears to be the norm.

The provocative suggestion that the Moon landings were faked is what evolutionary biologist Richard Dawkins would call a successful тете. Like the gene, it is self-replicating; an idea that has the requisite characteristics that allow it to sustain and be passed from one credulous mind to the next carried forward because it can easily replicate through a population who are largely scientifically illiterate. Distorting facts to support a false theory is a straightforward exercise, especially with a sprinkling of pseudo-scientific jargon, when the audience lacks the tools, and often the inclination, to examine them critically. To refute these false tales requires intellectual rigour and a well-grounded knowledge of the physical world, the possession of which would likely inoculate a person from taking such claims seriously in the first place. One of my motives for writing this book was to provide a little of the knowledge that might help to refute the absurd assertion that Apollo was faked.

Another reason behind the book was a desire to share something of my own personal journey in reaching an understanding of how this wonderfully audacious adventure was achieved. Like so many of my age. Apollo happened at an impressionable lime in my life. I was only just old enough to realise that a flight to the Moon would be an incredible, fantastic thing to attempt; at which point. I watched America promptly realise that dream before my eyes. The enchanting, almost primeval sense of wonder that this adventure left with me transcends its grubby, political roots, and has never really departed with childhood. Then the arrival of the internet in our household, soon after the 25th anniversary of the Apollo 11 landing, blew pure oxygen over the embers of this fascination. It lit a vigorous fire because, for the first time, I could find material that explained in great detail just how this difficult endeavour was executed. Equally important w;as being able to connect with others w’ho had been similarly touched by Apollo, eventually having the honour to link up with some of those who were lucky enough to have taken part.

This book and my personal journey through Apollo, discovering how it all functioned and what happened on another world, owe an endless debt of gratitude more to one man than to any others I have encountered along the wny. Geographical distance has so far prohibited me from having the opportunity to shake his hand and thank him personally, as he lives on the other side of the w’orld. Yet the internet allows me to count him as one of my closest friends. Eric Jones Look on the monumental task of compiling a journal of the first era of lunar exploration after he became frustrated at how’ his country had shelved the lessons learned after they had spent billions of dollars going to the Moon. Inspired by J. C. Beaglehole’s journals of Captain James Cook’s explorations 200 years earlier, he recounted and explained every moment the Apollo crew’s spent on the lunar surface. By making his efforts freely available on the internet, I and people from around the world came on board, adding our time and talents to make the Apollo Lunar Surface Journal w’ebsite one of the most remarkable historic documents from the twentieth century.

My chosen role was to extend the journal to include the flying portions of the missions the journey to the Moon, from the Moon and the time spent in orbit around it. Taking Eric’s w’ork as my model, I set out to explain w’hat w;as occurring moment by moment, and w’hile doing so. I learned more than I could have imagined about how. at a broad level, the Apollo jigsaw fitted together. This book is my attempt to pass on this knowledge to a wider audience.

Most of the book will Lake the reader through the various stages of the Apollo flights, from before their spectacular launches at Kennedy Space Center in Florida to the decks of the aircraft carriers that recovered the crews from the Pacific Ocean a week or two later. For newcomers to the subject, I have devoted the first two chapters to an outline of Apollo’s genesis and achievements; and have included a bibliography at the end of the book that will provide years of excellent reading for those who wish to delve further.

This is the tale of how Apollo flew’ to the Moon and how the United States of America brought together the finest of its people and skills to achieve a dream as old as the human race, to turn the ancient light in the sky into a world to be explored. It describes the efforts involved not only in successfully flying to the Moon, but also in returning safely, to provide knowledge and a new perspective on the human position within the cosmos.

к may be appropriate to mention here a few points on general terminology, as American engineers, scientists and technologists have a habit of constructing long descriptive names for their ideas and systems, which they promptly shorten to an acronym. Their use of the resulting words and phrases then settles into a form that is often chaotic and contradictory. In this book. I have been unable to avoid filling the text with some of the same arcane acronyms that clog up so much discussion of technical matters. However, many that I have used are so ubiquitous in the Apollo story that they will soon be seen as old friends, and readers will be well served by making them a familiar part of their vocabulary. Notes have been included in the glossary in order to point out the various and inconsistent wnys in which acronyms were pronounced.

Through my own science and engineering education, I have a bias towards the use of SI units and. as a result, those units have been used throughout the book. This is a controversial path to tread as it is often pointed out to me that those who carried out the achievement used ‘English’ or ‘Imperial’ units, and that it would only be proper for books on the topic to do likewise. This argument holds no more weight for me than the suggestion that books on Egyptology should exclusively be written in cubits. SI is the dominant system of scientific and engineering expression in the world. NASA began to use it for its science publications in 1970 and even Apollo’s onboard computer did its internal sums in metric. It therefore seems appropriate to explain Apollo in units that will have the widest possible understanding. Where English units are used in dialogue, a suitable SI equivalent will be near at hand.

So here’s my book, and I hope you like it.

IN David Woods Bearsden Scotland January 2011

Despite the weight advantages that were gained from the adoption of the lunar orbit rendezvous concept, an Apollo spacecraft and lander were still a huge mass to lift off Earth and send to the Moon, and a very special rocket would be needed for the task.

In every way, the Saturn V epitomised the sheer audacity of the Moon programme. It was big – in size, thrust and weight; it required huge facilities to build, test, transport and launch; and its engines consumed massive quantities of propellant at prodigious rates. It also demanded fine, subtle control of the
enormous forces it produced, and it stretched the will of NASA even to have conceived it. The fact that they did was perhaps because, at the outset, its designers had considered an even larger vehicle. In comparison, the Saturn V may have seemed relatively straightforward but when the time came to turn ideas to reality, its procurement strained the IJS aerospace industry every bit as much as the spacecraft it carried.

The lineage of the Saturn V led back to a pre-war German amateur rocketry club, the VfR (Verein fur Raiicnsehffahrt or Society for Space Travel) where a young Wernher von Braun first shone as a gifted rocket engineer and motivator of men. As Adolf Hitler rearmed Germany, its military, denied conventional long-range artillery by the Versailles treaty, took an interest in the successes of the VfR and how its new rocket technology could be applied to sending warheads towards an enemy.

Von Braun headed a group of engineers based at Peenemunde, a peninsula on the large island of Usedotn on Germany’s Baltic coast, where his Л-4 rocket, fuelled by alcohol and liquid oxygen, was developed. Towards the end of the war, conventional warheads were installed on the A-4 and the propaganda ministry renamed the rocket V-2 or Vergeltungswaffe 2 ( Vengence 2). An explosion in Chiswick, London, on 8 September 1944, signalled the first use of the V-2 as a weapon. Thousands of these rockets, built largely by slave labour under the control of the notorious Schui/.siaffel (the SS) were launched in an attempt to ruin the morale of the British population.

As the Allied forces marched across Huropc in the war’s final days, teams of intelligence specialists searched for useful military technology. Von Braun knew that the knowledge and experience of his engineers would be a great prize for whichever Allied power reached them first. The Soviets w ere closer but he preferred the western option, and arranged for his team to surrender themselves to the American forces. Additionally, he helped his captors to retrieve hardware and documents that would prove useful to them. Though he shamelessly used the military as a means to develop his rocket, von Braun had something else on his mind space travel.

In 1956. the US Department of Defense made the IJS Air Force responsible for procuring the country’s long-range missiles. Over the succeeding years, the USAF and the companies that worked for it developed the Atlas. Thor and Titan missiles. In the meantime, von Braun’s group, still part of the US Army – initially based at the White Sands Proving Ground in New Mexico but now’ at the Army Ballistic Missile Agency in Huntsville, Alabama – had already devised the Redstone and Jupiter missiles. The former was America’s first rocket capable of sending a payload into orbit. After the Soviet Union started the space race by launching Sputnik on 4 October 1957. von Braun’s Juno I rocket (a Redstone with solid-fuelled upper stages) countered for America by placing the more scientifically useful Explorer I into high orbit. However, rockets were inextricably lied up with the nuclear weapons they were designed to carry, and because by now’ America had lightweight nuclear devices, its rockets tended to be lower pow’ered and less useful as lifting vehicles for spacecraft. Soviet nuclear weapons were large, heavy affairs, and therefore their rockets, being more powerful, made better space vehicles. Realising this shortcoming, von Braun’s team first added solid-fuelled rockets to the top of their Jupiter missile, which was essentially a scaled-up Redstone, to make the Juno II space launcher, and then progressed to the development of a heavy-lift booster specifically for space use. Initially designated the Super Jupiter, this booster would cluster first-stage engines and tanks to achieve the desired thrust. This project evolved into the Saturn. As early Saturn development continued into I960, von Braun’s team found themselves transferred to NASA with, at last, a civilian role for their rockets. Their facilities in Huntsville became the Marshall Space Flight Center, with von Braun as its director. Once President Kennedy’s lunar goal had been set, the development of the Saturn rockets became a key part of the civilian space effort, with their final design being firmly linked to the needs of the Apollo spacecraft they would carry.

Though an entire family of launchers were envisaged, only three Saturn rockets came out of the programme. The Saturn 1 was primarily a development scries that proved the concepts of engine clustering in order to achieve high thrust levels as well as testing early Apollo hardware. The Saturn IB used an improved form of the first stage and made use of a new, highly efficient rocket stage, the S-IVB. which was manufactured by the McDonnell Douglas Company. This stage would be crucial to the Apollo programme. As well as being the second stage of the Saturn IB. it formed the third stage of the Saturn V, in which role it would provide the final impetus to take all NASA’s manned spacecraft to the Moon. The Saturn IB was a man-rated vehicle that could take either a CSM or a LM, but not both, to Earth orbit.

The big member of the Saturn family of launchers was the Saturn V, so-called because, in von Braun’s mind, there were three paper configurations after the Saturn I that were never built. In truth, its NASA’s early plans shifted, there were many configurations that were put on paper to match machines to missions. Many of these used varying quantities of two engines that were under development, the F-l and the.1-2, but it was the iconic Saturn V, which could lift both the CSM and the LM, that utilised them to fulfil the lunar goal.

Most of the major components and procedures required for a Moon landing had been tested, though not always in the context in which they would be needed during a lunar flight. In order to minimise the surprises that might face the landing mission, NASA wanted to practise a complete lunar mission as far as they dare, short of beginning the final descent to the Moon. This dress rehearsal flight, the F-mission, was accomplished by Apollo 10, flown by Tom Stafford, Eugene Cernan and John Young. Their spacecraft were named after characters in Charles Schulz’s popular cartoon strip Peanuts, who had also featured in NASA campaigns to promote quality control in the programme. The CSM was therefore named Charlie Brown while the LM took the name Snoopy.

Launch took place on 18 May 1969 and. for the first time, all the functions of the CSM to take a lunar module to an orbit 110 kilometres above the Moon had to work. Once the two docked spacecraft had successfully entered a lunar parking orbit, the crew settled down for their first night in the Moon’s vicinity as their ship hurtled above its surface at 5.800 kilometres per hour. Next day. Stafford and Cernan entered Snoopy’і cabin, separated from Young in Charlie Brown, and took the LM into the same low orbit from which a landing mission would make its final descent. This orbit brought Snoopy down to an altitude of less than 14,500 metres above the lunar terrain from where Stafford photographed and described the approach to the landing site that had been selected. The most important task was to prove that lunar

orbit rendezvous would work as planned. After they jettisoned the descent stage, the ascent engine was used to set up an orbital situation similar to that which would be presented after lift-off from the Moon. NASA’s management had once been wary of the idea of two speeding craft being brought into close proximity while in orbit around another world, and they wished to prove that their techniques worked prior to committing a lander to the surface. This successful rendezvous and docking finally cleared the way to a landing attempt.

Thanks to the usual predictability of the gathered media, Apollo 10 is more often remembered for the ‘son-of-a-bitch’ language Cernan used when a pilot error caused the LM to gyrate unexpectedly as the descent stage was being jettisoned. The journey home was uneventful except for the unprecedented colour television coverage of a receding Moon that was beamed to Earth soon after Charlie Brown’s SPS engine was fired. Stafford had promoted the importance of TV on Apollo, not only to the public, but also to engineers and lunar scientists. The 8-day flight of Apollo 10 put NASA on the home straight, leaving the G-mission with no unknowns except the landing itself.

At the very tip of the Saturn V stack, the rounded point of the launch escape lower (LET) included eight small holes which led to a device called the Q-ball. Shortly before launch, a cover was removed that had protected these holes from debris and insects. Their function was not dissimilar to the pitot tube seen on conventional aircraft for measuring airspeed, because the Q-ball similarly measured air pressure as the vehicle rammed through the atmosphere during the ascent. However, the point of eight holes on the Saturn was not to measure airspeed, but to measure whether the air was hitting them equally and thereby determine whether the rocket was flying straight and true through the atmosphere. The angle-of-attack that they sensed was displayed on a dial for the crew’s benefit. If the flight had to be aborted, and the spacecraft pulled clear by the escape tower, the Q-ball would then help to determine which way round the command module and tower were flying.

With two minutes to go, a crewman pulled a knob in the cabin which stopped coolant flowing to radiators on the side of the spacecraft. Normally, in space, these panels received hot liquid from the cooling system and shed that heat by radiation. However, as the rocket ascended, the frictional heat generated by passing through

the atmosphere warmed the radiators, temporarily making them counterproductive, and so for the few minutes of ascent they were bypassed.

With much of the atmosphere behind it and the second stage working smoothly, the

Saturn changed the way it guided itself to orbit. So far. it had not compensated for any distance that the wind and other forces had pushed it from its ideal flight path. Nor had it tried to correct for any under – or over-performance of the engines. Instead, during the tilt sequence, the instrument unit had merely kept track of where it was at any moment. The new guidance regime was given a typically NASA-cse name of the iterative guidance mode. While in force, equations in the Saturn’s computer plotted the most efficient flight path from ‘wherever the vehicle was’ to The point in space where it wanted to go’ – in this case, insertion into a parking orbit around Earth. To anthropomorphise the situation, what the computer was thinking was, “OK, 1 know where the wind and such has pushed me to. What must 1 do to reach the position and speed that I have to reach?” As the S-II powered ahead, the computer monitored the vehicle’s progress and sent steering commands to the four gimballed outer engines as necessary to achieve the desired result. This steering was maintained for the rest of the S-II burn. It was then suspended and the stack’s attitude held steady until the S-II had dropped away and the third stage had ignited to pow’er the vehicle to orbit. With the S-IVB thrust established, the steering recommenced.

To help visualise the flight path to the Moon, imagine a vantage point looking dowm at Earth and the Moon from the north, with an Apollo spacecraft about to make a TLI burn for a free-return path. The spacecraft’s orbit around Harth is towards the east (anticlockwise in our visualisation), a direction it shares with the rotation of Harth. and indeed almost everything else in the solar system. The TLI burn is Limed to occur at a point in this orbit that is essentially on the opposite side of Earth from where the Moon and spacecraft will come together in three days. The burn places the spacecraft on a path that ordinarily would be a long, slow elliptical orbit with an apogee half a million kilometres out from Earth, somewhat beyond lunar distance. Meanwhile, at TLI the Moon is about 40 degrees further back in its path around Earth, moving at one kilometre per second towards the point where its orbit intersects the spacecraft’s path. The timing of TLI is such that the spacecraft reaches lunar distance shortly before the Moon comes along.

As it heads out, the influence of Earth’s gravity on the spacecraft gradually weakens while that of the Moon, approaching from the side, grows stronger; it attracts the spacecraft and deflects it from its original anticlockwise elliptic path. By virtue of careful calculation of the required trajectory, the spacecraft is aimed to pass near the Moon’s leading hemisphere and be pulled around its far side travelling in a clockwise direction. If nothing else is done, and if the timing and direction are correct, such a trajectory will, under the Moon’s gravitational influence, swing right around the lunar far side and fall back to Earth. Such a path would make its closest approach about midway around the far side and in order to stay in the Moon’s vicinity, the crew; must fire their main engine against their direction of travel at this

point. This bum will take energy out of the spacecraft’s trajectory, slow it down and make it enter a clockwise, or retrograde lunar orbit.

The measurement of radial velocity relied on the Doppler effect, whereby the movement of a transmitter altered the received pitch or frequency of whatever wave was being transmitted. This is familiar to most people as the change in pitch of a constant note, perhaps from an engine or a horn, as it passes the listener. We hear its pitch drop as it passes by and departs. The same effect applies to radio transmissions where the frequency of the received signal changes slightly according to whether the transmitter is approaching or receding from the receiver. This frequency can be accurately measured and, by knowing the precise frequency with which it was transmitted, the velocity of the transmitter can be calculated. The system is similar in some respects to radar speed traps used to catch speeding car drivers.

To use the Doppler effect well, the frequency of the transmitted signal from the spacecraft had to be known with great precision. Onboard equipment to generate a signal of sufficient accuracy – one whose frequency was precise and stable despite the thermal extremes of space, w’ould have been excessively heavy and power-hungry. However, an elegant solution existed that kept the heavy equipment on the ground, yet could yield a measurement that was inherently more accurate.

Given that a powerful, aeeurate radio signal would in any case be sent to the spacecraft to carry voice and data from mission control, engineers simply arranged that it be modified on board in a known way. and retransmitted back to the ground, this lime carrying voice and data from the spacecraft. If the frequency of the signal from Earth was precisely known, then so was that from the spacecraft if it were not moving.

For Apollo, the ground station transmitted data and voice signals from mission control to the spacecraft on a carrier signal called the uplink. This carrier was synthesised from a very accurate frequency standard installed at the station. Ground stations supporting the Apollo programme had some of the most accurate frequency standards available at the Lime. For the CSM, the carrier had a frequency of 2.106.4 MIIz while that for the LM was 2,101.8 MHz. On reception by the spacecraft antenna, an onboard transponder Look this signal, multiplied its frequency by the ratio of 240/221 (about 1.086) and sent it back to Earth, using this new signal as the carrier for the downlink.

When received by the ground station, the precise frequency of the downlink was measured and compared to the uplink. If the precise 240/221 relationship was maintained, the spacecraft was neither approaching nor moving away from the ground station, such as when moving across the face of the Moon perpendicular to the line of sight to the ground station. A higher received frequency meant that the spacecraft was approaching; a lower frequency indicated receding motion. This was a very powerful system because it measured Doppler shift over both the up and down legs of the signal’s journey, doubling the sensitivity of the system to the point where it could even detect the velocity change caused by the minuscule thrust that was generated when the crew’ dumped their urine overboard.

Buried within the pie-shaped struc­ture of the service module were two (later three) tanks each of oxygen and hydrogen. Although these two sub­stances are excellent propellants for rocket engines, in this case propulsion was not their purpose.

A common notion is that space­craft usually derive their electrical power from the Sun via large arrays of photovoltaic cells. While this is

generally true for automatic spacecraft in the inner solar system and for the International Space Station, the high power demands of a typical Apollo flight would have required such large panels as to make them cumbersome. This size would not have been a problem during a coasting flight, but when the spacecraft’s large engine was fired, the mechanical stress from the aeeeleration would have required the panels to be folded away at the very time that their power was most needed. Л second alternative is to use storage batteries to bring eleetrical power from Harth. Although they could have supported a short flight, as they did for the early manned Gemini flights, they could not support the Apollo spacecraft for two weeks without being prohibitively heavy.

It was up to the Gemini programme to prove the concept of a third alternative, the fuel cell, as a source of clcctrieiiy for long-duration flights, f irst developed before the Second World War in Britain, the operation of the alkali fuel cell is remarkably simple. It acts like a battery by using the chemical reaction of two substances, in this case oxygen and hydrogen, and it makes the energy of the reaction available in the form of prodigious quantities of electricity. However, unlike a conventional battery, the reactants can be replenished constantly. As long as fresh reactants are fed past the electrodes the fuel cell does not run down. Even more remarkable is the fact that the waste product of this reaction is water that is sufficiently pure to drink.

The adoption of the fuel cell in Apollo therefore killed two design quarries with one stone. Not only did it produce lashings of electricity (a single fuel cell could generate well over one kilowatt of electricity at peak demand), the water it produced became a sort of lifeblood of the spacecraft. It quenched the thirst of the crew and rchydraicd their food in metered amounts through a pistol-style ‘squirt gun’ on the end of a hose. It also supplemented the cooling of the spacecraft’s electronic equipment by being evaporated into space, taking heat with it. Any excess was periodically discarded through an orifice in the spacecraft’s hull.

The high-energy reaction that occurs when hydrogen and oxygen are burned in the combustion chamber of a rocket makes it greatly favoured by rocket engineers. In the Apollo fuel cell, most of this energy was expressed as electricity, but although it could reach efficiencies of 70 per cent, the reaction still yielded significant amounts of heat. Some of this was used to warm the extremely cold reactants before they entered the cell; the rest was rejected through eight radiator panels around the upper circumference of the service module. An early version of the fuel cell flew on seven of the Gemini flights which gave engineers a chance to iron out the teething troubles with this promising technology. By the time the Apollo programme finished Apollo 13’s oxygen tank explosion notwithstanding – no Apollo flight suffered from a failure of their fuel cells. It was one of the many technologies and techniques for which the Apollo programme depended on Gemini to pioneer.

Among the limitations of the Apollo fuel cell was that it was very sensitive to the presence of impurities in the reactants. Even with hydrogen and oxygen of the highest purity that NASA could procure, the build-up of contaminants required that the cells be purged from time to time to avoid the resultant loss of electrical power. Oxygen purges were carried out daily, while hydrogen purges happened every second day. Three switches on the LMP’s side of the main display console allowed the gases to he routed to any of the three cells for this function, hlcclric heaters were included to ensure that the purging gas was warm enough to avoid it freezing the water in the cells.

Apollo’s implementation of black-and-white television w as, by far, the simpler of the tw;o systems, and the less greedy of radio bandwidth. The camera, as used on Apollos 8, 9 and 11 had just one imaging tube and operated at scan rates that would normally be called slow-scan television. The frame rate used was only 10 frames per second with 320 lines per frame. There was no interlace. The bandwidth of the signal (which dictated how well the image handled fine detail) was restricted to a very low value of 0.4 MHz (as compared to about 5 MHz for contemporary broadcast TV). The camera used a vidicon type of imaging tube that was notorious at the time for its excessive image lag, and this caused a ghostly smear to trail behind the moving image.

When the pictures reached Earth at this non-standard frame rate, they were electronically incompatible with just about every TV system on the planet. Converters were installed at chosen ground stations to generate standard US television signals from the lunar TV. The converter worked in two stages. The first simply consisted of another vidicon TV camera aimed at a small television screen. The screen displayed the images from the Moon at 10 frames per second while the camera, which ran at 60 fields per second, was allowed to capture the screen only when a full image had been completed, which was every tenth of a second. In other words, only one field in six from the camera contained a picture.

The second stage was to recreate the missing five fields. The single good frame from the TV camera was recorded onto a magnetic disk which then replayed it five times to reconstruct the full 60-fields-per-second TV signal, ready for distribution to Houston. The repetition of the fields and additional lag from the second camera added to the ghostly impression left by Apollo ll’s moonwalk coverage.

A question that is often asked is, if Neil Armstrong was the first man on the Moon, who operated the TV camera? ft is a spurious question because it assumes that all cameras must have a cameraman behind them. In fact, Eagle’s camera was mounted inside a fold-down panel next to the ladder. At the top of the ladder, Armstrong pulled a lanyard to open the panel and thereby reveal the camera. The most ergonomic and lightweight way to mount the camera on this panel was upside – down, so on Earth, the conversion equipment had a switch which the operator flicked to right the upside-down picture. Once both crewmen were on the surface, Armstrong lifted the camera from its mount and placed it on a stand from where the TV audience could watch proceedings. The operator threw his switch back to restore the image’s orientation.

One day in 2003,1 said to prolific author David Harland that there was one book in me waiting to get out. "Right," he said, "and it’s my job to get it out of you.’’ Before I knew what was happening. I had started putting down what I had learned about the Apollo flights and, slowly, this book began to take form. I hope David likes what I produced, and I greatly acknowledge his wisdom, advice and support throughout the process.

I am particularly grateful to Clive Horwood and all at Praxis Publishing, and Maury Solomon at Springer for not only taking this project on when I had never previously delved into the world of book writing, but also for considering it worthy of a second edition. I also thank Alex Whyte for his copy editing work on the first edition and David Harland for his work on this new and expanded edition.

Over the past decade, as I probed deeper and deeper into how Apollo worked, I came across many other people who are all part of a loose group in society who. like me, watched the dream of Apollo being fulfilled as impressionable children, trie Jones was pivotal in bringing the depth of Apollo to a much wider audience through his unmatched Apollo Lunar Surface Journal. This journal is simply the best Apollo resource available, largely due to trie’s boundless generosity. We all owe him a huge debt of gratitude.

When 1 took my idea of an ‘Apollo Flight Journal’ to trie, he wisely pul me in touch with Apollo computer expert and self-proclaimed ‘geek’, Frank O’Brien. Frank was a little sceptical of the value of the AFJ at first, but soon changed his mind as we discovered the many layers of complexity that went into an Apollo flight. Frank’s knowledge is vast and deep, and I could never have penetrated Apollo’s subilcty without his guidance.

While writing this book, I leaned on others for advice, feedback and resources. In particular, I’d like to thank fellow Apollo students Tim Brandt, Ken MacTaggart, Lcnnie Waugh and Scott Schneeweis for comments and suggestions. Scott was also kind enough to supply photographs of items from his comprehensive collection of Apollo hardware.

In my professional life in TV broadcasting, I work among people who combine technical ability with creativity. Some have had to put up with me for years rabbiting

on about the Moon and Apollo. Л long time ago. Hedda MacLeod made it clear to me that she believed that I really ought to write a book and it is Hedda I thank for planting the seed that really made me think it in the realms of possibility. Some of my colleagues agreed to become guinea pigs, reading drafts and guiding me where I was going. I am therefore grateful to Martin MaeK. eny. ie and Ken Stirling for their feedback. With my cover, I wanted to hark back to the nuts-and-bolts science fiction I grew up with, where a flight to the Moon was a fantastic, futuristic promise. 1 also wanted to indicate to a prospective reader that the book’s contents would not be overly technical and I am grateful to Stew-art Ramsay for realising my vision for this edition.

I w’ould also like to thank my sister. Hilda Harvey, for her advice, feedback and encouragement. Hilda is no space geek but, while reading my drafts, she made me believe that the book could be made amenable to the wider public. In a similar vein, I am proud to mention my lovely wife, Anne, and my two wonderful sons. Stephen and Kevin, who were always there as sounding boards when I struggled for words and phrases and who read the text for me throughout our proofreading. My parents, Allan and Violet, always fostered my interest in space and spaceflight, buying their young son a telescope and sending me on astronomy courses. To them and all my sisters. I send love and thanks. I would also like to thank John Lightbody for his drawings that accompany my explanations of orbits and the state vector.

For me, Apollo 15 commander David Scott is the epitome of the Apollo lunar explorer. He has also been incredibly generous to those who have been compiling the Apollo journals. I am hugely grateful to him for his support throughout and for contributing the Foreword to this book. Other Apollo participants who were generous with their talcs over the years include astronauts A1 Worden and Jim Lovell; and members of mission control Gerry Griffin, Sy Liebergot and Chuck Dcilerich. Thanks also go to Stephen Garber and the staff at NASA’s History Division. For over a decade. Stephen has always been greatly supportive of the Apollo Flight Journal, upon which this book is based.

Among the justifications for producing a second edition was feedback from readers who pointed out occasional errors in the first edition or who provided me with a deeper understanding of various issues. In this respect. I am grateful to LM computer expert Don Eyles who shared his astonishing tales of the cutting edge of computer technology in spaceflight. Also to Jim Scotti for his input. Additionally I felt that I should expand the book with details of the surface exploration of the Moon and for my research, there was no better material than Eric Jones’ ALSJ and, once again, I am in Eric’s debt for this wonderful resource.

The majority of pictures that I have used in this book are courtesy of NASA and all effort has been made to determine the copyright owners for other images. In those few cases where this was difficult. 1 have used the images anyway owing to their historic importance, and relevant copyright owners should contact me and I will be pleased to give due credit in later editions.

Any errors in the book are my own but if any are spotted, please pass them to me via my publisher or the book’s website, w-ww-.hafttm. com. They will be considered in the event of a reprint or new edition.