Margaret Hamilton, Apollo software pioneer, dies at 90

Margaret Hamilton, a pioneering software engineer, passed away on Sept. 30, 2026, at the age of 90. She led the software engineering group at MIT’s Instrumentation Laboratory, which developed the Apollo Guidance Computer (the spacecraft’s guidance computer) for NASA’s Apollo flights. Margaret Hamilton entered the world in Paoli, Indiana, in 1936 and studied mathematics at the University of Michigan and Earlham College, earning her BA in 1958. She began her career at MIT’s meteorology department, developing weather‑prediction software alongside Edward Lorenz, a pioneer in chaos theory.

In 1965, she joined MIT’s Instrumentation Laboratory to work on the Apollo program, becoming its first female programmer. Hamilton faced sexism in a male‑dominated field but received support from colleagues who valued her dedication and commitment. The AGC provided astronauts with a DSKY keypad for navigation and spacecraft control, replacing the manual joystick controls used in Gemini missions.

It was the first computer to use silicon‑integrated circuits, and each Apollo mission carried two AGCs—one in the command module and one in the lunar module that landed on the Moon. Its core memory was hand‑woven from copper strands and magnets, requiring precise threading by professional seamstresses under Hamilton’s supervision. During Apollo 11’s lunar descent in July 1969, alarms 1201 and 1202 triggered in the lunar module, prompting mission control to consider aborting the landing.

Hamilton identified the alarms as non‑critical after recognizing a radar switch error from prior simulations, allowing the mission to proceed. Her team ensured that no one reported any software bugs during any crewed Apollo mission through rigorous testing and error detection, and she coined the term “software engineering” to describe this work. Hamilton’s meticulous debugging included testing programs repeatedly; she once used her daughter’s accidental activation of a program (P01) to refine error handling, and her example inspired many women to pursue STEM careers.

After Apollo, Hamilton contributed to Skylab and the space shuttle programs and founded two software companies: Higher Order Software in 1976 and Hamilton Technologies in 1986. She received NASA’s Exceptional Space Act Award in 2003 and the Presidential Medal of Freedom in 2016 for her contributions to space exploration and software engineering. A LEGO Women of NASA set featuring Hamilton, Sally Ride, Mae Jemison and Nancy Roman debuted in 2017.

Hamilton’s practices in software development, including rigorous testing and error detection, reshaped modern computing and software education. She received the Michael Collins Trophy in 2025 for her achievements in space exploration, collected by her daughter due to her frailty.