Margaret Hamilton, who led software development for Apollo program, dies at 90

Margaret Hamilton, who died Sep. 30 at 90, was a pioneering computer scientist who led development of the onboard flight software for NASA’s Apollo program at MIT’s Instrumentation Lab. After beginning her programming career in meteorology and on the SAGE air-defense system, she joined Apollo in 1965 as the project’s first programmer and rose to lead teams that grew to more than 400 people by 1968. She championed software reliability and “defensive” programming, famously anticipating user errors in the so-called Lauren error and designing priority-driven task scheduling that allowed the Apollo 11 lunar landing to proceed safely after a 1202 computer alarm indicated an overload caused by a hardware fault.

Hamilton turned her Apollo-era methods into a career as an entrepreneur and author of over 130 publications. She founded Higher Order Software and later Hamilton Technologies, which developed the Universal Systems Language and tools to systematize error prevention, fault tolerance, and reliable systems engineering. Her work established software engineering as a discipline, earning wide recognition including the 2016 Presidential Medal of Freedom. Her legacy endures in modern practices for building safety-critical, fault-tolerant software and in the institutions she helped shape at MIT and Draper Laboratory.