⭐️ Howie Roak

Margaret Elaine Heafield: August 17, 1936 – September 30, 2026

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✪ Margaret Elaine Hamilton (née Heafield) was an American computer scientist who directed the Software Engineering Division at the MIT Instrumentation Laboratory, where she led the development of the on-board flight software for NASA’s Apollo Guidance Computer for the Apollo Space Program. She later founded the private software companies Higher Order Software in 1976 and Hamilton Technologies in 1986; both headquartered in Cambridge, Massachusetts.

During her research and development career, Hamilton published more than 130 papers, proceedings, and reports, covering sixty projects, and six major programs. She was the first to coin the term software engineering, stating, “I began to use the term ‘software engineering’ to distinguish it from hardware and other kinds of engineering, yet treat each type of engineering as part of the overall systems engineering process.”

On November 22, 2016, Hamilton was awarded the Presidential Medal of Freedom in recognition of her work leading to the development of on-board flight software for NASA’s Apollo moon missions.

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Margaret Heafield was born on August 17, 1936, in Paoli, Indiana to Kenneth Heafield and Ruth Esther Heafield (née Partington). The family later moved to the Upper Peninsula of Michigan. Margaret graduated from Hancock High School in 1954.

Margaret studied mathematics at the University of Michigan in 1955 before eventually transferring to Earlham College in Indiana, where her mother had also been a student. There, she earned a Bachelor of Arts (BA) degree in mathematics with a minor in philosophy in 1958. She cited Florence Long, the head of the math department at Earlham, as helping with her desire to pursue abstract mathematics and become a mathematics professor. She said her poet father and headmaster grandfather inspired her to include a minor in philosophy in her studies.

In Boston, Hamilton first planned to enroll in graduate study in abstract mathematics at Brandeis University. However, in mid-1959, Hamilton instead began working for Edward Norton Lorenz, in the Meteorology Department at Massachusetts Institute of Technology (MIT) where she developed software for weather prediction and programming on the LGP-30 and the PDP-1 computers at Marvin Minsky’s Project MAC. Her work contributed to Lorenz’s future publications on chaos theory.

From there, Hamilton took a role as a programmer at MIT Lincoln Laboratory in 1961, working on the Semi-Automatic Ground Environment (SAGE) project; the United States’ first air defense system. Hamilton said of her work on SAGE:

“What they used to do when you came into this organization as a beginner, was to assign you this program which nobody was able to ever figure out or get to run. When I was the beginner they gave it to me as well. And what had happened was it was tricky programming, and the person who wrote it took delight in the fact that all of his comments were in Greek and Latin. So I was assigned this program and I actually got it to work. It even printed out its answers in Latin and Greek. I was the first one to get it to work.“

Hamilton also recalled that it was while working on SAGE that she began to understand the importance of software quality, particularly software stability: a new and largely unexplored concept at the time. 

She met her first husband, James Cox Hamilton, in the mid-1950s while attending college. They married on June 15, 1958, the summer after she graduated from Earlham. She briefly taught high school mathematics and French at a public school in Boston, Indiana. The couple then moved to Boston, Massachusetts, where they had a daughter, Lauren, who was born on November 10, 1959. They divorced in 1967 and Margaret married Dan Lickly two years later. Margaret and Dan Lickly divorced in the early 1970s.

In 1965, Hamilton was preparing to pursue graduate studies when her husband saw an advertisement in the newspaper: The Instrumentation Lab at MIT was seeking people to develop software to “send a man to the moon.” The lab had won the contract from NASA to build the onboard flight software for the Apollo program. Intrigued by the challenge, Hamilton applied, and was hired as the first programmer for the Apollo Project at MIT, as well as the first female programmer in the project. Hamilton was initially hired as a programmer for this process but moved on into systems design.

Her first program for the Apollo mission involved lunar landmark tables for an unmanned mission to the Moon. After the mission had already launched, it was discovered that the tables had been entered in reverse order. Nevertheless, the mission was still ultimately successful.

Hamilton recalled during the next Apollo mission, she was still treated as a novice programmer. She believed this was why she had been assigned to write a contingency program which was never intended to be executed. She even named the program “Forget It.” However, the program would later prove crucial when an unlikely scenario actually occurred. Afterwards, Hamilton became the mission expert, and control was handed over to “Forget It.”

By 1968, she was the assistant director in charge of the Command and Service Module team, with more than 400 people working on the Apollo Program’s software. 

“From my own perspective, the software experience itself (designing it, developing it, evolving it, watching it perform and learning from it for future systems) was at least as exciting as the actual events surrounding the mission,” Hamilton told MIT News in 2009.

“There was no second chance. We knew that. We took our work seriously, many of us beginning this journey while still in our 20s. Coming up with solutions and new ideas was an adventure. Dedication and commitment were a given. Mutual respect was across the board. Because software was a mystery, a black box, upper management gave us total freedom and trust. We had to find a way, and we did. Looking back, we were the luckiest people in the world; there was no choice but to be pioneers.”

In time, she became Director of the new Software Engineering Division and was responsible for the team writing and testing all onboard in-flight software used for the Apollo spacecraft’s Command and Lunar Module and for the subsequent Skylab space station.

Olivier de Weck, the Apollo Program Professor at MIT, later called Hamilton “a pioneer” in the new field of software engineering and “a fundamental contributor” to the Apollo program. He added she not only was an advanced systems programmer in her own right, but also headed the team which successfully developed “one of the most complex systems humanity had ever achieved.”

In one of the critical moments of the Apollo 11 mission, the Apollo Guidance Computer, together with the on-board flight software, averted an abort of the landing on the Moon. Three minutes before the lunar lander reached the Moon’s surface, several computer alarms triggered. According to software engineer Robert Wills, Buzz Aldrin entered the codes to request the computer display altitude and other data on the computer’s screen. The system was designed to support seven simultaneous programs running, but Aldrin’s request was the eighth. This action was something he requested many times while working in the simulator. The result was a series of unexpected error codes during the live Moon descent. The on-board flight software captured these alarms with the “never supposed to happen displays” interrupting the astronauts with priority alarm displays.

Hamilton had thought long and hard about this. It meant if Aldrin, say, hit a button on the priority display too quickly, he might still get a “normal” response. Her solution: when you see a priority display, first count to five.

Hamilton’s priority alarm displays interrupted the astronauts’ normal displays to warn them that there was an emergency “giving the astronauts a go/no-go decision (to land or not to land).” Jack Garman, a NASA computer engineer in mission control, immediately recognized the meaning of the errors presented to the astronauts by the priority displays and shouted, “Go, go!” and they continued. Paul Curto, a senior technologist who nominated Hamilton for a NASA Space Act Award, called Hamilton’s work “the foundation for future ultra-reliable software design.”

Hamilton also co-founded with Saydean Zeldin a company called Higher Order Software (HOS) to further develop ideas about error prevention and fault tolerance emerging from their experience at MIT working on the Apollo program. Hamilton was the CEO of HOS and later left the company. In March 1986, she founded Hamilton Technologies, Inc. in Cambridge, Massachusetts.

Hamilton has been credited with being the first to use the term “software engineering.” Hamilton detailed how she came to make up the term “software engineering:”

“When I first came up with the term, no one had heard of it before, at least in our world; and, it was an ongoing joke for a long time. They always liked to kid me about my radical ideas. It was a memorable day when one of the most respected hardware gurus explained to everyone in a meeting that he agreed with me that the process of building software should also be considered an engineering discipline, just like with hardware. Not because of his acceptance of the new ‘term’ per se, but because we had earned his and the acceptance of the others in the room as being in an engineering field in its own right.”

When Hamilton began using the term “software engineering” during the early Apollo missions, software development was not taken seriously compared to other engineering disciplines, something she aimed to change. Over time the term “software engineering” gained the same respect as any other technical discipline.

Writing in Wired, Robert McMillan noted: “At MIT she assisted in the creation of the core principles in computer programming as she worked with her colleagues in writing code for the world’s first portable computer.” Hamilton’s contributions and innovations go far beyond just playing an important role in getting humans to the Moon. According to Wired‘s Karen Tegan Padir: “She, along with that other early programming pioneer, COBOL inventor Grace Hopper, also deserve tremendous credit for helping to open the door for more women to enter and succeed in STEM fields like software.”

On April 28, 2017, she received the Computer History Museum Fellow Award, which honors exceptional men and women whose computing ideas have changed the world. In 2022, she was inducted into the National Aviation Hall of Fame in Dayton, Ohio.

Hamilton died on September 30, 2026 at the age of 90, at a hospital in Cambridge, Massachusetts, due to multiple organ failure. ✪