Margaret Hamilton, the computer scientist who led development of the onboard flight software for NASA's Apollo program, died on September 30 at a hospital in Cambridge, Massachusetts, her daughter Lauren Hamilton told The Associated Press. MIT News reported the death on October 7, saying she was 90.

Hamilton led the Software Engineering Division of MIT's Instrumentation Lab, which held NASA's contract for Apollo's onboard flight software, and by 1968 she was assistant director in charge of the Command and Service Module team, with more than 400 people working on Apollo's software under her leadership.

Hamilton is credited as one of the founders of software engineering as a discipline — a term she popularized herself. According to MIT News, she said she began using the phrase 'software engineering' to distinguish it from hardware engineering, though at first 'it was considered to be quite amusing.

It was an ongoing joke for a long time.' She authored over 130 publications and later founded two companies, Higher Order Software in 1976 and Hamilton Technologies, whose flagship product is the Universal Systems Language.

In 2016, President Barack Obama awarded her the Presidential Medal of Freedom.

Her most famous contribution came during the Apollo 11 landing in July 1969. Moments before the Eagle was set down, the onboard computer raised a 1202 error after a hardware switch fault overloaded it.

According to MIT News, Hamilton's team had engineered priority-driven software that shut down unnecessary background tasks to protect mission-critical ones, and Houston trusted the software and let the landing proceed.

NASA said the software's intervention, which came just three minutes before touchdown, 'permitted the mission to safely continue.'

According to MIT News, an early example of her 'defensive' programming came from 'the Lauren error': her four-year-old daughter Lauren crashed a command module simulator by activating the pre-launch program P01 mid-flight.

Hamilton proposed a software fix, but was overruled because trained astronauts were presumed unlikely to repeat the mistake.

During Apollo 8 in 1968, Jim Lovell did exactly that, wiping navigational data in flight, and Hamilton's team was called in to recover — after which her changes were integrated into the program.

Hamilton spent two decades at MIT from 1959 to the mid-1970s, beginning with weather prediction software for meteorology professor Edward Lorenz, work MIT News says later informed his chaos theory publications, and then the SAGE air defense project at Lincoln Laboratory.

Later in life she became a celebrated symbol of women in technology: the famous photo of her beside a towering stack of Apollo code listings circulated online, and a 2017 Lego 'Women of NASA' set included her figure.

Her daughter told the AP that recognition surged around the Apollo 11 50th anniversary in 2019.

Tributes have come from across the space community. MIT's Olivier de Weck, the Apollo Program Professor, called her a pioneer 'ahead of her time' by 'a dramatic understatement,' and Draper CEO Jerry Wohletz said she left an 'indelible mark' on the lab that spun out of MIT's Instrumentation Lab.

NASA Administrator Jared Isaacman said on X that her work helped make humanity's first journeys to the moon possible, according to the AP. She also received NASA's Exceptional Space Act Award in 2003, and her legacy now rests with the generations of engineers — particularly women — she inspired.