The Early NASA Missions: The Computers That Took Us to the Moon
NASA’s early missions, such as the Mercury, Gemini, and Apollo programs, are celebrated as groundbreaking achievements in human space exploration. But behind the iconic images of astronauts and rockets lies another story—one of the computer systems that made these missions possible. These early computers, while revolutionary for their time, are astonishingly primitive compared to the technology we have today.
1. The Mercury Missions and the IBM 7090
In the late 1950s and early 1960s, NASA’s Mercury missions aimed to put a human in space and return them safely. The computer system used during these missions was the IBM 7090, one of the first commercial, fully-transistorised computers. The IBM 7090 was a workhorse, handling the extensive calculations needed to launch a spacecraft into orbit. It operated at a speed of 42,000 instructions per second, which was groundbreaking at the time.
Fun Fact: The average smartphone today is millions of times more powerful than the IBM 7090. To put it into perspective, while the IBM 7090 filled an entire room, the processor in your pocket can perform billions of operations per second, fitting into a device that weighs less than 200 grams!
2. The Apollo Missions and the Apollo Guidance Computer (AGC)
When NASA set its sights on landing a man on the moon with the Apollo program, they needed something more advanced—thus, the Apollo Guidance Computer (AGC) was born. Developed by the MIT Instrumentation Laboratory, the AGC was installed on the Apollo command and lunar modules. It featured a groundbreaking, real-time computing system capable of guiding and navigating the spacecraft.
The AGC had only 64KB of memory and operated at a clock speed of 0.043 MHz. In comparison, the average smartphone today has 8GB of memory and processors running at 3 GHz or higher. Despite its limited specs, the AGC was instrumental in managing complex tasks such as guidance, navigation, and control during the lunar landing.
Mind-Blowing Snippet: The AGC’s memory was made using a process called rope memory, where copper wires were threaded through magnetic cores. It was literally hand-woven by women in factories, many of whom had previously worked in the textile industry. Each bit of data was a physical loop or absence of a loop, making programming a physical act!
3. Comparing Early Space Computers to Modern Technology
It’s fascinating to compare the computers that powered the Apollo missions to modern technology. The AGC had the power equivalent to the first Apple II computer released in 1977, which itself is considered a relic by today’s standards. Even the most basic digital wristwatch today has more computational power than the AGC.
However, it’s important to recognise that while the raw computing power of these early machines was low, they were programmed with extreme efficiency. Engineers had to optimise every line of code due to the limited memory and processing capabilities. The AGC’s software had to work perfectly, as even a minor error could have had catastrophic consequences.
Interesting Fact: During the Apollo 11 mission, the AGC famously displayed a 1202 error due to overload, but the software was designed to prioritise critical functions over less important tasks. This allowed the mission to proceed, and Neil Armstrong and Buzz Aldrin successfully landed on the moon. Without this clever prioritisation, the landing might have been aborted!
4. Gemini Missions and the Beginnings of Onboard Computing
Before the Apollo program, NASA’s Gemini missions (1961-1966) acted as a bridge between Mercury and Apollo, focusing on long-duration spaceflights and spacewalks. Unlike the Mercury missions, Gemini spacecraft were equipped with onboard computers—the Gemini Digital Computer (GDC). This early onboard computer handled navigation calculations in real-time, which was essential for executing complex maneuvers such as rendezvous and docking.
The GDC was much less powerful than the AGC, and it had only 7KB of memory. However, it was one of the first examples of using computers to manage spacecraft operations beyond Earth’s atmosphere.
Modern Comparison: Today’s spacecraft, like those used by SpaceX, rely on advanced AI and high-speed processors that can make millions of calculations per second. The Falcon 9, for example, has multiple computers with modern processors that manage everything from launch sequences to landing procedures autonomously.
5. Legacy and Impact: What We’ve Learned
The computers used during NASA’s early missions may seem primitive today, but they laid the foundation for modern computing in space exploration. The development of the AGC, for example, was crucial in advancing real-time computing and embedded systems—both of which are now integral to everything from cars to medical devices.
Furthermore, the engineers and programmers behind these early systems had to push the boundaries of what was possible with extremely limited resources. Their pioneering work has inspired generations of scientists, engineers, and tech enthusiasts, proving that innovation isn’t just about power—it’s about ingenuity.
Statistic: In 1969, it cost NASA approximately $150 million (equivalent to $1 billion today) to develop the Apollo Guidance Computer. Meanwhile, the average consumer smartphone, which is millions of times more powerful, costs between £500-£1000.
Final Thoughts: Technology Then vs. Now
While it’s easy to marvel at how far we’ve come—from room-sized computers to pocket-sized supercomputers—it’s important to remember the immense ingenuity that went into those early systems. The engineers at NASA didn’t have the luxury of vast memory or fast processors, but they had creativity, precision, and a pioneering spirit.
The technology that powers today’s space missions—whether it’s SpaceX, Blue Origin, or the latest Mars rovers—owes much of its success to the foundational work done during NASA’s early missions. These groundbreaking efforts not only got us to the moon but also set the stage for the technological revolutions we enjoy today.
Interested in learning more about the technology behind early NASA missions? Check out these resources: