Margaret Hamilton, Software Pioneer Behind the Apollo Moon Landings, Dies at 90

Margaret Hamilton, the software engineer who led the team that wrote the onboard flight code for NASA's Apollo missions and whose work is credited with saving the Apollo 11 moon landing in its final minutes, died Sept. 30 at age 90, MIT announced this week. A cause of death was not disclosed.

Hamilton, born in Paoli, Indiana, in 1936, arrived at MIT in 1959 for what she expected to be a temporary job writing weather-prediction software with the meteorologist Edward Lorenz. She moved on to the SAGE air-defense program before being hired in 1965 as the first programmer, and the first woman, assigned to the Apollo project at MIT's Instrumentation Laboratory. By 1968 she was assistant director overseeing more than 400 engineers building the guidance software for the Command and Service Module.

The alarm that nearly aborted a landing

Hamilton's defining contribution came from an argument she had been making for years: that software should anticipate the mistakes astronauts might make under pressure, not merely trust that procedures would be followed correctly. In 1968, during Apollo 8, an astronaut accidentally triggered a prelaunch program in flight, and Hamilton's proposed safeguards against exactly that kind of error were adopted into the code.

The decision paid off eighteen months later. Minutes before Apollo 11's lunar module touched down in July 1969, a hardware glitch flooded the guidance computer with more data than it could process, triggering a 1202 program alarm. Because Hamilton's team had built the software to recognize its own priorities, it shed lower-priority tasks and kept the critical landing functions running, allowing Neil Armstrong and Buzz Aldrin to continue their descent.

"To say Margaret Hamilton was a pioneer — to say she was ahead of her time — would be a dramatic understatement," said Olivier de Weck, an MIT professor and interim head of its aeronautics and astronautics department, in the university's statement. Jerry Wohletz, chief executive of Draper Laboratory, the MIT spinoff that grew out of the Instrumentation Lab, said the company would "honor her legacy at Draper forever."

Founding a discipline

Hamilton is widely credited with popularizing the term "software engineering" at a time when writing code for safety-critical systems had no established professional standards. She later founded two companies, Higher Order Software and Hamilton Technologies, built around fault-tolerant design principles she had developed for NASA, and published more than 130 technical papers over her career.

President Barack Obama awarded her the Presidential Medal of Freedom in 2016, citing her role in having "defined new forms of software engineering." CNN and other outlets noted that NASA Administrator Jared Isaacman called her "a pioneer whose work helped make Apollo and humanity's first journeys to the moon possible."

Hamilton is survived by her daughter, Lauren Hamilton; son-in-law, Richard Selesnick; two grandsons; four great-grandchildren; and siblings John, David and Kathryn. News reports citing MIT say a memorial service is planned for next spring in Cambridge, Massachusetts. Software engineers still cite her Apollo-era insistence on anticipating failure as the ancestor of modern safety-critical coding standards used in aviation, medical devices and spacecraft today.