Artemis and Apollo: The Systems That Took Them to the Moon — and Brought Them Home
Watching the Artemis II mission last week, I was struck by some parallels - and differences - between it and Apollo 13. Artemis II’s Integrity landed back on Earth on the 11th of April, the same day Apollo 13’s Odyssey was launched. Externally, the two capsules appear similar, albeit Integrity is larger and carries a crew of four instead of three. Internally, however, over half a century of technological progress separates them. Nowhere is this more evident than in the computing power available to the astronauts. While computers are ubiquitous today, in the 1960s, they were in their infancy and the Moon landings were not only a triumph of human effort, ingenuity, and dedication, but also a triumph of one of humanity’s newest tools: the computer.
Quoted from The New York Times, July 17th 1969, just before the first Moon landing:
“If I had to single out the piece of equipment that, more than any other, has allowed us to go from Earth-orbit Mercury to Apollo lunar trips in just over seven years, it would be the high-speed computer”
— Christopher C. Kraft, Jr., NASA’s Director of Flight Operations, Manned Spacecraft Center, Houston.
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| Mary Jackson was one of the “human computers” who used IBM's digital computers. She was portrayed in the film “Hidden Figures.” (NASA) |
While scarce elsewhere in the world, computers were everywhere in the Apollo program - from the planning to the construction through the testing to the flights themselves, humans simply couldn’t handle the mass of information and perform the necessary calculations fast enough and effectively enough.
The largest computers used, and the ones with the most versatile roles, were in the basement of Houston’s mission control building. There, the Real Time Computing Complex (RTCC) was filled with IBM mainframes which monitored every aspect of the flights, delivered up-to-the-moment accurate information to the flight controllers, calculated past, present, and future positions of the spacecraft, and, finally, delivered digital commands and information to the spacecraft.
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| Mission Control Console and RTCC Mainframes (NASA/IBM) |
Every console at mission control displayed a certain subset of the information analyzed by the RTCC computers — the flight M.D. saw telemetry which showed the heart and breathing rate of the astronauts, the EECOM engineer observed the spacecraft’s own vital signs (the Electrical, Environmental and COMmunication systems), and the FIDO (Flight Dynamics Officer) engineer monitored and controlled the direction in which the spacecraft flew.
While those state of the art IBM model 360 mainframes are veritable tortoises compared even to today’s slowest commercial computers, they were indispensable to handle the overwhelming amount of information generated by the myriad components of the Apollo missions to the Moon - too much information to be managed in time by mere mortals.
Much of the vast amount of information managed by the jack-of-all-trades IBM mainframes was generated by other, more specialized, computers. Planning and practicing for the flights began years before they occurred. Specialized simulators enabled the astronauts to practice both the “happy path” of the mission and see how they could handle unexpected errors and mishaps along the way. Other computers were used to handle the communication equipment and shepherd the precious data (telemetry, radio communication and television) from the spacecraft to Houston, even when the Moon was below the horizon in Texas. These dedicated computers were built by a variety of companies such as Computer Control Company, General Electric, UNIVAC, and others.
The most famous of the Apollo computers were the spacecraft computers themselves — the ones the astronauts used to control the spacecraft and travel from the Earth to the Moon. Designed by the Draper computer lab in MIT and built by Raytheon, the Apollo Guidance Computer (AGC) was a marvel of 1960’s miniaturization, which weighed a mere 32 kilograms (70 pounds) and had a specialized 20 button keyboard panel which was robust enough to be used by astronauts with thick gloves, whilst floating weightless in space.
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| Entering commands into the Display and Keyboard (DSKY) of the Apollo Guidance Computer during a simulation. (Image from MIT/Draper) |
One last computer was hidden within the gargantuan Saturn V Moon rocket — the IBM Instrument Unit was the independent brains and control system for the first minutes of each Moon mission.
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| The Saturn V Instrument Unit and components (NASA/MSFC) |
This computer was so well built that it survived a direct lightning strike during the launch of Apollo 12! As the chief designer of the Saturn rocket, Wernher von Braun was wont to say — “As the Instrument Unit [the IBM-built computer] goes, so goes the Saturn.”
Apollo 13 landed successfully after their adventure almost exactly 56
years ago, thanks to the heroic work of the teams working around the clock here
on Earth. A few months after the landing, the astronauts sent a letter of thanks
to the IBM team.
One of my favorite artifacts in my collection is
a letter the Apollo 13 crew sent to IBM a few months after their recovery. Here
it is, flanked by the Apollo capsule in the water and the Lunar Lander – reproduced
in Lego.
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Letter from Apollo 13 astronauts to IBMers (from my personal collection) |
Dear IBMer:
Our Apollo 13 mission was one of the most hazardous in space history. If our flight taught us anything, it was that we must have excellence in every area of Apollo. The risks involved are such that we simply cannot settle for anything less.
As an IBMer, you can indeed be proud of your company’s role in Apollo. IBMers in Huntsville, Houston, Cape Kennedy, Goddard and Owego have done an outstanding job of ensuring us a safe flight. We’ve come to rely on the performance of the Instrument Unit and the ground-based computers and systems support provided by IBM. Through all of your company’s areas has run the same theme: excellence, both of systems and individuals. We and all of our fellow astronauts are depending on you to keep up the good work, for there are more manned flights to come.
Just before the Apollo 13 launch, one of us told a newsman: “Perhaps we’ve gotten complacent about manned space flight, but the risks are there.” The world knows now just how serious those risks can be. We won’t soon forget those words. We hope that every person involved in Apollo will bear them in mind in everything he does.
Through the Mercury and Gemini missions and on every Apollo flight, astronauts have learned to count on that traditional IBM dedication to excellence. We will continue to count on it during the many flights to come. It is reassuring to us that quality is a tradition in your company. To you, excellence is a matter of pride. To us, it is a matter of survival.
Please accept our heartfelt thanks for the achievements of the past. We are counting on IBM’s support to keep the Apollo/Saturn team a winning one in the future.
Sincerely,
James Lovell Jack Swigert Fred W. Haise
More information about the mainframes which powered Mission Control is available in this fascinating lecture by my colleague Mark Nelson, who has been telling the story of “Mainframes and the Moon” since 2019 to anyone who will listen.
After the triumph of Apollo, IBM has continued developing its products and itself. Perhaps uniquely, this centenarian company has successfully reinvented itself many times over the decades. Today it continues to push the boundaries of AI, quantum computing and sustainability. At the same time IBM has not forgotten its promise to the Apollo astronauts and continues to work hand in hand with NASA.
This year, IBMPower computers ran Artemis II's Launch Control System during the countdown, the system processed and monitored hundreds of thousands of telemetry data points through sensors dispersed throughout the launch system and reported on system health of both rocket and spacecraft systems.
More than half a century after Apollo 13, the technology has changed almost beyond recognition. Yet, much like that damaged spacecraft on its long journey home, what ultimately matters is still what continues to work - before, during, and after things go wrong, and the tools we use to make that possible. When lives depend on the systems we build, reliability is not a feature; it is the mission.
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