The Apollo Guidance Computer

The Apollo Guidance Computer was invented by Doc Draper, as he was also called by colleagues and employees. He headed the team that developed the guidance, navigation and control system for Apollo 11. Only this made it possible for Apollo 11 to land precisely on the moon. And to bring the astronauts safely back home to Earth again afterwards.

Dr Charles Stark Draper was born in 1901 and graduated from Stanford University in 1922 with a bachelor’s in Psychology. He then switched to MIT, where he first gained a BSc in Technical Electrochemistry in 1926. Then in 1928, an MSc in Physics. Finally, he went on to earn his PhD in Physics in 1938.

Learning from practice

In spite of his undeniable technical genius, Draper was anything but a mere theoretician or a nerd. This much was already clear when he started his studies at MIT. He was surely the only student who took his professors flying on a plane to discuss the problems of aerodynamics with them. But, not only that. He was also a ballroom dancer, a boxer and a basketball player. Even when he became a professor at MIT and ultimately founded the MIT Instrumentation Laboratory in 1940, he continued to stick by his conviction that it was impossible to teach advanced engineering using books alone. Students should also be required to solve practical problems.

During the Second World War, he applied this philosophy to design a system that employed gyroscopes to stabilise anti-aircraft artillery. After the war, he worked with colleagues to develop the gyroscope-based “inertial guidance system”. During a test flight in 1953, this navigation system safely guided an aircraft from Boston to Los Angeles. Without using external landmarks for reference and without any pilot input. Through this navigation system, Draper became known as the “father of inertial navigation”. In fact, Draper was on board the flight, which was typical behaviour for him. He had full faith in his developments and always preferred to gain first-hand, practical experience of them.

Maximum motivation

This was also true for the Apollo mission’s guidance system. In an ultimate vote of confidence, Draper volunteered to fly to the moon using the system developed at his institute. He wrote a letter to NASA that said the following: “I realize that my age of 60 years is a negative factor in considering my request, but … I will gladly undergo any physical examinations and tests that may be prescribed and will take any courses of training that may be recommended.” Naturally, his request was turned down, and Draper never flew into space. Yet this letter reflects the extraordinary commitment showed to his technologies. This quote is also attributed to him: “We at the Instrumentation Laboratories are going full throttle on the Apollo guidance work. … If I am willing to hang my life on our equipment, the whole project will surely have the strongest possible motivation.”

Draper was not only known for his talent in motivating his colleagues, but also for his leadership style. He assembled some of the brightest minds of the age at his research institute, which brought extremely well educated – albeit very diverse – people together in one place. Additionally, he was known for setting tasks that brought them well out of their respective comfort zones and exposed them to new experiences. He wanted colleagues to find out for themselves exactly what they could contribute to the tasks. At the same time, he gave them a long leash. His colleagues had the opportunity to test the water in various fields and subjects until they found somewhere they felt comfortable. In doing so, he provided space for each individual to be creative.

The world’s first embedded system

Within a relatively short period, Draper did indeed manage to produce a flawlessly functioning navigation system for the Apollo mission. From an electronics perspective, the real triumph of this achievement was the on-board computer, which could not be any larger than one cubic foot. This brief sent designers back to the drawing board, although they did make use of the integrated circuits that had just been launched onto the market. The computer featured a keyboard that the astronauts could use to ask questions and enter data. It performed its tasks reliably despite having astonishingly small storage capacity by today’s standards. Nowadays, this master computer is considered to be the world’s first “embedded system”.

With his “learning by doing” philosophy, Charles Stark Draper’s career mirrors one of the fundamental shifts in 20th-century science: the transformation of academic theory into (business) practice. Since 1988, in recognition of the weight of Draper’s achievements, the US National Academy of Engineering has been awarding the Charles Stark Draper Prize, one of the most prestigious honours for engineers and somewhat akin to a Nobel Prize in these disciplines. This distinction is given to recognise innovative engineering achievements that contribute to the welfare and freedom of mankind.


The Apollo Guidance Computer – the first Embedded System

Apollo Guidance Computer
The Apollo Guidance Computer developed by Dr Charles Stark Draper was used in the Apollo programme’s command modules and lunar modules. Overall, it was taken along on 15 manned missions.


  • Dimensions: 61 × 32 × 17 centimetres
  • Weight: 32 kilograms
  • Processor: 2,800 ICs, each with dual NOR-3 gates
  • Clock frequency: 2,048 Hz
  • Memory: 15-bit RAM
  • Required energy: 50 watts


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