Margaret Hamilton, the computing pioneer whose software put the first NASA astronauts on the moon, has died at age 90.
Hamilton's death — of unspecified causes, on Sept. 30 — was announced Wednesday by the Massachusetts Institute of Technology, where she worked from 1959 until the mid-1970s.
"To say Margaret Hamilton was a pioneer — to say she was ahead of her time — would be a dramatic understatement," said Olivier de Weck, interim head of the MIT Department of Aeronautics and Astronautics, in a statement. "She not only developed advanced code herself but also led a team in using that nascent technology to develop one of the most complex systems humanity had ever achieved."
Hamilton, who grew up in Indiana, earned a BA in mathematics with a minor in philosophy from Earlham College in 1958. She moved to Boston the following year — so her husband could pursue his law degree — and took a job in the meteorology department at MIT, working with the professor who discovered chaos theory.
It was her first foray into software engineering. Hamilton then got a programming job in another lab, working on the Semi-Automatic Ground Environment (SAGE) project, the United States' first air defense system.
"She had so much foresight in thinking through the ways that humans would use computers, and to create reliable systems that could be used even in the highest-risk, life and death kind of environments," said Teasel Muir-Harmony, curator of the Apollo Collection at the Smithsonian National Air and Space Museum.
In 1961, MIT's Instrumentation Lab won the NASA contract to develop software for the Apollo project. Hamilton saw a newspaper advertisement seeking people to develop the software to "send man to the moon," and applied. She was the first female programmer hired for the Apollo missions, starting with uncrewed flights and moving to onboard software.
By 1968, she had worked her way up to assistant director in charge of the Command and Service Module team, leading a crew of over 100 engineers. Hamilton was in her early 30s, as were many of her colleagues in the nascent field of software engineering — a term she herself is credited with coining.
"In this period where she was working, this is a brand new field, and she really helped to define it," Muir-Harmony said. "Margaret Hamilton, like many of the people who worked on the Apollo program, helped really develop computing as we know it today."
Hamilton made an impression with her problem-solving and leadership skills. She often brought her daughter, Lauren, then 4, to the lab — resulting in an infamous "Lauren error."
"Her daughter overloaded a system during some kind of a test. And she thought, 'Oh my gosh, this is something that could actually happen in outer space. So I better account for this,'" said Dean Robbins, an author who published a book about Hamilton in 2017. "So her daughter actually played a part in her technical achievements."
Hamilton was known for her focus on "defensive" programming, building software that could anticipate and solve errors on its own.
"Her goal wasn't simply to build a system that worked when everything went right," Muir-Harmony said. "It was to build a system that could continue working when things went wrong."
Perhaps the most famous example of that is the Apollo 11 mission in 1969. Just three minutes before the first humans were supposed to touch down on the moon, alarms went off on board, signifying computer overload. Fortunately, Hamilton's team had built a system that could shut down unnecessary background tasks at that moment.
"Mission Control was able to recognize what was happening, able to trust the computer … to prioritize tasks, to know that the astronauts could continue … with the first lunar landing," Muir-Harmony said.
After leaving MIT, Hamilton founded two software engineering companies. She received the Presidential Medal of Freedom from Barack Obama in 2016, and the following year was immortalized in miniature as part of a "women of NASA" Lego set.
Hamilton is also the subject of a black-and-white photo from 1969 that often makes the rounds on social media, showing a young woman with long hair and glasses, smiling as she stands beside a towering stack of notebooks — filled with the code that sent humans to the moon.
But despite public recognition in her later years, Robbins said Hamilton was "not one to toot her own horn." In fact, she initially shied away from the idea of a biography and only agreed because she thought it would be fun to read with her great-grandchildren. (She is survived by four great-grandchildren, two grandsons, her daughter and son-in-law and three siblings.)
"She really warmed up to explaining what she had done, developing the software," he recalled. "She got very excited about telling me all about the technical aspects of developing this. And she was sending me photos and actual code that she had written, and pictures of the primitive machinery that they'd had to use back in the 1960s."
The entire process was painstaking. Muir-Harmony explained that programs were stored on the Apollo guidance computer by hand-weaving copper wire through magnetized cores ("which basically looked like little donuts"). As the overseer of that process, Hamilton earned the nickname "rope mother" in the lab.
Robbins struggled to simplify all of that for his grade-school audience, until he realized: Hamilton's story was all about problem-solving. And she broke barriers for women in the process.
"There was no playbook for how to use computers to get astronauts to the moon," he said. "She had to come up with it on the fly and under tremendous pressure. And I think she was proud of that in her own modest way."
Hamilton told MIT News in 2009 that from her perspective, the software experience was "at least as exciting as the events surrounding the mission."
"Looking back, we were the luckiest people in the world," she said. "There was no choice but to be pioneers."
Copyright 2026 NPR
