Margaret Hamilton: Her Codes Sent Us to the Moon

A century after Maria Mitchell paved the way for women to learn astronomy in a formal classroom and a few decades after the Harvard Computers laid the foundation for the discovery of distant galaxies, Margaret Hamilton wrote more than 10 books of software codes—by hand—that would send men to the moon for our first giant leap.

Margaret Hamilton was just 32 years old, an MIT graduate, and a mother of a six-year old kid when she led a group of programming engineers to design the Apollo software that would launch Neil Armstrong and Buzz Aldrin to the moon safely.

When I first got into it, nobody knew what it was that we were doing. It was like the Wild West.

The software programming section was a small sector in the entire Apollo program, with only using 100 engineers working in Margaret Hamilton’s team. “At the beginning, nobody thought software was that big a deal. But then they began to realise how much they were relying on it,” said Margaret Hamilton to The Guardian. The software memory that Apollo used was 1 million smaller than the phone we have today. In contrast to the glamor and the theatrics of Saturn X’s towering 363 feet tall rocket—still the heaviest rocket every built, the software programming sector was much more traditional, hand-made, and low-tech.

Codes were written on books, large sheets of paper, and a keypunch operator would create holes in paper cards, keying the codes into what were called punch cards. “Not too many people know what punch cards are anymore, but that’s how you programmed it,” says Paul Ceruzzi, a curator emeritus at the Smithsonian’s National Air and Space Museum.

After the codes were done—copied with hands by her team—the codes were sent to a factory to be manually ‘threaded’ through metal cores. “If the wire goes through the core, it represents a one. And around the core it represents a zero,” Hamilton explained in the documentary Moon Machines. The actual weaving of the codes into the machine was done solely by hands by a group of women, fondly called Little Old Lady memory.

Core Rope Memory

The software programming field, which decades later would transform the world, was in its infancy and barely had any name. It was not yet a discipline, had no experts in the field; it was an ominous mystery.

 When answers could not be found, we had to invent them; we were designing things that had to work the first time, and our systems had to be ‘man-rated.’ Many on the team began as fearless 20-something-year-olds. The greater the challenge, the more fun we had. And, yet, dedication and commitment were a given. There was no time to be a beginner. Learning was by being and doing, and a dramatic event would often dictate change.

Margaret Hamilton was young, radical, and fearless. “She was also really expansive as a programmer, coming up with solutions for problems, very innovative, very outside-the-box thinking. That, I think, is reflected in her career choices and the work she did in the lab,” said Teasel Muir-Harmony, a curator also at the Air and Space Museum.

Even as a mother and one of the very few women in the program, she “was so involved in what we were doing, technically, that I was oblivious to the fact that I was outnumbered by men.  We concentrated on our work much more than whether one was male or female.”

The radical embrace towards the unknown, to me, embodies her interdisciplinary-studies that she had earned from her parents, which culminated in her decision to choose Philosophy as a minor.

There were other heroes outside of the technical world—my father who was a philosopher and a poet, and my grandfather who was a writer, a head schoolmaster and a Quaker minister. All were instrumental in my minoring in philosophy in college. All of these influences from those related to the fields of mathematics and philosophy helped to decide and integrate what was important for the path that I would take in the fields of computer science and systems design and software engineering.

Echoing Einstein’s wisdom that “imagination is more important than knowledge,” and also many others who preceded or succeeded her, such as John Muir, Rachel Carson, and Carl Sagan, Margaret Hamilton was equipped by her own artistic endeavors that perhaps were the secrets to her creative solutions in this unnamed, abstract field:

 I believe it is also important to learn (or be around) things like music, art, philosophy, linguistics, and math including logic; any of which could help improve one’s being an excellent programmer/problem solver/thinker and to have a more global perspective on things. The ultimate goal would be that of teaching one how to think (design).

Her photo at MIT that had gone viral, a snapshot that juxtaposes her small figure with a towering set of books where the Apollo codes were written in, showcased her radiant, child-like joy. She often brought her daughter to work in the evening or during the weekend—probably another radical thing to do at a time when working mothers were still rare—and let her play in the command module simulation (in fact, it was due to Lauren’s irresistible urge to play and hack the system, Margaret Hamilton saw another potential for failure in her codes).


Margaret Hamilton and her daughter

Other than being an absolute powerful woman who’s behind Apollo 11’s historic feat, to me, Margaret Hamilton radiates this inner-child quality—always curious, always inquisitive—that was perhaps her infinite source of energy and curiosity to be one of the very few women who work in this male-driven industry, and to work in a field that is yet to be named. As she said:

There was no choice but to be pioneers.

More readings:

P.S. I write children’s story for adults about the moon. See it here. Or email me to purchase


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