Margaret Hamilton, who coined the term “software engineering” andled the developmentof on-board flight software for NASA’s Apollo program in the 1960s,died last weekat the age of 90. A recipient of the Presidential Medal of Freedom in 2016, Hamilton was also immortalized as aLEGO minifigthe following year—part of the “Women of NASA” set that also included astronauts Mae Jemison and Sally Ride.

“To say Margaret Hamilton was a pioneer—to say she was ahead of her time—would be a dramatic understatement. She was a software engineer at a time when that field was in its infancy, and 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,”said Olivier de Weck, interim head of the MIT Department of Aeronautics and Astronautics. “The Apollo program still stands as one of our greatest testaments to the power of collaboration, ingenuity, and engineering, and Hamilton was a fundamental contributor to that program’s success.”

Born in 1936 in Paoli, Indiana, Hamilton graduated from Earlham College in 1958 with a degree in mathematics and a minor in philosophy—the latter a nod to her father (a poet) and grandfather (a headmaster). She married her first husband, James Cox Hamilton, that same year. The plan was for her to work until he finished his law degree, after which he would support her through graduate school to earn a PhD in mathematics.

She ended up working for Edward Lorenz, the MIT mathematician who set out to construct a mathematical model of the weather using a set of differential equations representing changes in temperature, pressure, wind velocity, and the like. You’ve probably heard the famous story of how Lorenz kept a continuous simulation running on his LGP-30 computer, and of that fateful 1961 day when he realized that even small differences in starting values could lead to very different outcomes—a sensitivity to initial conditions that is a hallmark of chaos theory, along with strange attractors. You might not have known that it was Hamiltonwho was responsiblefor programming the LGP-30.