The Apollo Guidance Computer

The technological marvel that facilitated the Apollo missions to the Moon was the on-board computer. In the 1960s most computers filled an entire room, but the spacecraft’s computer was required to be compact and low power. Although people today find it difficult to accept that it was possible to control a spacecraft using such a ‘primitive’ computer, it nevertheless had capabilities that are advanced even by today’s standards. This is the first book to fully describe the Apollo guidance computer’s architecture, instruction format and programs used by the astronauts. As a comprehensive account, it will span the disciplines of computer science, electrical and aerospace engineering. However, it will also be accessible to the ‘space enthusiast’. In short, the intention is for this to be the definitive account of the Apollo guidance computer. Frank O’Brien’s interest in the Apollo program began as a serious amateur historian. About 12 years ago, he began performing research and writing essays for the Apollo Lunar Surface Journal, and the Apollo Flight Journal. Much of this work centered on his primary interests, the Apollo Guidance Computer (AGC) and the Lunar Module. These Journals are generally considered the canonical online reference on the flights to the Moon. He was then asked to assist the curatorial staff in the creation of the Cradle of Aviation Museum, on Long Island, New York, where he helped prepare the Lunar Module simulator, a LM procedure trainer and an Apollo space suit for display. He regularly lectures on the Apollo computer and related topics to diverse groups, from NASA's computer engineering conferences, the IEEE/ACM, computer festivals and university student groups.

evolution of the Apollo Guidance Computer, Mr. Hall contends that the development of the Apollo computer supported and motivated the semiconductor industry during a time when integrated circuits were just emerging. This was the period just before the electronics revolution that gave birth to modern computers. In addition, the book recalls the history of computer technology, both hardware and software, and the applications of digital computing to missile guidance systems and manned spacecraft. The book also offers graphics and photos drawn from the Draper Laboratories archives that illustrate the technology and related events during the Apollo project. Written for experts as well as lay persons, Journey to the Moon is the first book of its kind and a must for anyone interested in the history of science and the relevance of computer technology to space exploration.

The incredible story of how human pilots and automated systems worked together to achieve the ultimate achievement in flight—the lunar landings of NASA’s Apollo program As Apollo 11’s Lunar Module descended toward the moon under automatic control, a program alarm in the guidance computer’s software nearly caused a mission abort. Neil Armstrong responded by switching off the automatic mode and taking direct control. He stopped monitoring the computer and began flying the spacecraft, relying on skill to land it and earning praise for a triumph of human over machine. In Digital Apollo, engineer-historian David Mindell takes this famous moment as a starting point for an exploration of the relationship between humans and computers in the Apollo program. In each of the six Apollo landings, the astronaut in command seized control from the computer and landed with his hand on the stick. Mindell recounts the story of astronauts’ desire to control their spacecraft in parallel with the history of the Apollo Guidance Computer. From the early days of aviation through the birth of spaceflight, test pilots and astronauts sought to be more than “spam in a can” despite the automatic controls, digital computers, and software developed by engineers. Digital Apollo examines the design and execution of each of the six Apollo moon landings, drawing on transcripts and data telemetry from the flights, astronaut interviews, and NASA’s extensive archives. Mindell’s exploration of how human pilots and automated systems worked together to achieve the ultimate in flight—a lunar landing—traces and reframes the debate over the future of humans and automation in space. The results have implications for any venture in which human roles seem threatened by automated systems, whether it is the work at our desktops or the future of exploration.

In 1966 the author, newly graduated from college, went to work for the MIT laboratory where the Apollo guidance system was designed. His assignment was to program the complex lunar landing phase in the Lunar Module's onboard computer. As Apollo 11 approaches, the author flies lunar landings in simulators and meets the astronauts who will fly the LM for real. He explains the computer alarms that almost prevented Neil Armstrong from landing and describes a narrow escape from another dangerous problem. On Apollo 14 he devises a workaround when a faulty pushbutton threatens Alan Shepard's mission, earning a NASA award, a story in Rolling Stone, and a few lines in the history books. This memoir is a new kind of book about Apollo. It tells a story never told before by an insider -- the development of the onboard software for the Apollo spacecraft. It makes a vertical connection between technical details and historic events, but by broadening the story using his own experiences as he grows into adulthood in the 1960s the author draws a parallel between that era of successful space exploration, and the exploration, inner and outer, that was taking place in the culture.

The untold story of the historic voyage to the moon that closed out one of our darkest years with a nearly unimaginable triumph In August 1968, NASA made a bold decision: in just sixteen weeks, the United States would launch humankind’s first flight to the moon. Only the year before, three astronauts had burned to death in their spacecraft, and since then the Apollo program had suffered one setback after another. Meanwhile, the Russians were winning the space race, the Cold War was getting hotter by the month, and President Kennedy’s promise to put a man on the moon by the end of the decade seemed sure to be broken. But when Frank Borman, Jim Lovell and Bill Anders were summoned to a secret meeting and told of the dangerous mission, they instantly signed on. Written with all the color and verve of the best narrative non-fiction, Apollo 8 takes us from Mission Control to the astronaut’s homes, from the test labs to the launch pad. The race to prepare an untested rocket for an unprecedented journey paves the way for the hair-raising trip to the moon. Then, on Christmas Eve, a nation that has suffered a horrendous year of assassinations and war is heartened by an inspiring message from the trio of astronauts in lunar orbit. And when the mission is over—after the first view of the far side of the moon, the first earth-rise, and the first re-entry through the earth’s atmosphere following a flight to deep space—the impossible dream of walking on the moon suddenly seems within reach. The full story of Apollo 8 has never been told, and only Jeffrey Kluger—Jim Lovell’s co-author on their bestselling book about Apollo 13—can do it justice. Here is the tale of a mission that was both a calculated risk and a wild crapshoot, a stirring account of how three American heroes forever changed our view of the home planet.

The New York Times bestselling, “meticulously researched and absorbingly written” (The Washington Post) story of the trailblazers and the ordinary Americans on the front lines of the epic Apollo 11 moon mission. President John F. Kennedy astonished the world on May 25, 1961, when he announced to Congress that the United States should land a man on the Moon by 1970. No group was more surprised than the scientists and engineers at NASA, who suddenly had less than a decade to invent space travel. When Kennedy announced that goal, no one knew how to navigate to the Moon. No one knew how to build a rocket big enough to reach the Moon, or how to build a computer small enough (and powerful enough) to fly a spaceship there. No one knew what the surface of the Moon was like, or what astronauts could eat as they flew there. On the day of Kennedy’s historic speech, America had a total of fifteen minutes of spaceflight experience—with just five of those minutes outside the atmosphere. Russian dogs had more time in space than US astronauts. Over the next decade, more than 400,000 scientists, engineers, and factory workers would send twenty-four astronauts to the Moon. Each hour of space flight would require one million hours of work back on Earth to get America to the Moon on July 20, 1969. “A veteran space reporter with a vibrant touch—nearly every sentence has a fact, an insight, a colorful quote or part of a piquant anecdote” (The Wall Street Journal) and in One Giant Leap, Fishman has written the sweeping, definitive behind-the-scenes account of the furious race to complete one of mankind’s greatest achievements. It’s a story filled with surprises—from the item the astronauts almost forgot to take with them (the American flag), to the extraordinary impact Apollo would have back on Earth, and on the way we live today. From the research labs of MIT, where the eccentric and legendary pioneer Charles Draper created the tools to fly the Apollo spaceships, to the factories where dozens of women sewed spacesuits, parachutes, and even computer hardware by hand, Fishman captures the exceptional feats of these ordinary Americans. “It’s been 50 years since Neil Armstrong took that one small step. Fishman explains in dazzling form just how unbelievable it actually was” (Newsweek).

Apollo was built in the era of "big iron" computer mainframes. The concept of an onboard computer for space missions was radically new. There was only one place in the world that could design the Apollo Guidance Computers, and that was MIT. It took most of the U.S.'s production of integrated circuits, another radical idea replacing individual vacuum tubes, to build the AGC's. It took 2,000 person-years of independent code review and validation to ensure that they would operate properly. Besides the technical challenges, the Apollo missions were a matter of National Prestige. In the Space Race between the United States and the Soviet Union, President Kennedy said we were going to the Moon and return safely before the end of the (1960's) decade, so we did. The flight computers for the Saturn launch vehicle were an evolution of earlier missile guidance efforts. The massive Saturn-V first stage was built from clustered Jupiter rockets. The earlier and smaller Saturn-I was built of clustered Redstone rockets, which were themselves a derivative of the early German V-2 rockets by the Von Braun Team. The Saturn's upper stages were all new technology, using liquid hydrogen and oxygen. The vehicle had to achieve and maintain a precise trajectory from its launch site in Florida, to lunar orbit, to the lunar surface and back, and then return to Earth. All this took unprecedented computing power. This book is a brief synopsis of the architecture and applications of the Apollo computers. There is a lot of archived material on the topic, and the list of references in this book is a good starting point. The amazing thing is, the first computer on another world was designed and built before computers were commodity items. It worked as planned. Although your phone has more computing power than the entire Saturn vehicle, you shouldn't trust it to get you to the moon and back.