When Margaret H. Hamilton started writing computer code at MIT as a young working mother in 1960, the term “software engineer” did not exist, and programmers occupied the fringes of a nascent aerospace field dominated by nuts-and-bolts engineering and draft work.
By the end of the decade, programming had more than proved its worth — and Hamilton and her colleagues at the future Draper Laboratory had played a critical role in landing man safely on the moon.
That was just one achievement in a pioneering half-century in software engineering that landed Hamilton on stage Tuesday at the White House, where the 80-year-old Cambridge resident was one of 21 recipients of the Presidential Medal of Freedom, the nation’s highest civilian honor.
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This year’s honorees included Bill and Melinda Gates, Kareem Abdul-Jabbar, and Bruce Springsteen, part of a group President Obama hailed as “extraordinary Americans who have lifted our spirits, strengthened our union, pushed us toward progress.”
Working in alphabetical order, Obama draped the medal — a five-pointed star framed by golden eagles — around Hamilton’s neck immediately before conferring the same honor on actor Tom Hanks, and after architect Frank Gehry.
The president recalled the historic flight of Apollo 11. Three minutes before the spacecraft was set to touch down on the moon, an alarm rang out. But software designed by a team that included Hamilton helped sort out what mattered most, determining that the alarm wasn’t signaling a major problem.
“Our astronauts didn’t have much time, but thankfully they had Margaret Hamilton,” Obama said. “Margaret led the team that created the on-board flight software that allowed the Eagle to land safely.”
Hamilton, the president continued, “symbolizes that generation of unsung women who helped send humankind into space. Her software architecture echoes in countless technologies today, and her example speaks of the American spirit of discovery that exists in every little girl and little boy who know that somehow to look beyond the heavens is to look deep within ourselves and to figure out just what is possible.”
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Hamilton studied math at Earlham College in her home state of Indiana before moving with her husband to Cambridge so he could attend Harvard Law School. Initially, she took a programming job at MIT to pay the bills, delaying her own graduate work; instead, she found a calling, drawn to the problem-solving challenges inherent in complex programming.
She worked first on the national missile-defense computer system known as SAGE. Then MIT’s Instrument Laboratory got the contract to design the guidance, navigation system, and controls for the Apollo spacecraft. That work involved over 1,000 people and required inventing the first portable computer as well as the software for that hardware, said Deborah G. Douglas, collections director and science and technology curator at the MIT Museum.
Hamilton rose to lead the in-flight software group and is best known for her role behind the Apollo 11 alarm bell incident highlighted by the president. Hamilton’s team designed the software to sound an alarm if the computer’s processor became overloaded but also to prioritize tasks if that warning rang, focusing on the most critical, said Bill Barry, NASA’s chief historian. That allowed Mission Control and the astronauts to avoid aborting the mission when alarms sounded minutes before landing, because of a radar hardware switch that turned out to be in the wrong position.
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Hamilton went on to become head of the Software Engineering Division at MIT’s Instrumentation Laboratory, staying through its spinoff into Draper Laboratory. She left in the mid-1970s to found her own company, and is recognized within the programming world for helping lay the groundwork for “modern, ultrareliable software design and engineering,” as her award noted.
Douglas said Hamilton emerged from a sometimes-forgotten era in which women were far more prevalent in computing, though they were often relegated to rote operation and number-crunching.
“But this is not somebody just dotting Is and crossing Ts,” she said. “Margaret Hamilton is at the vanguard of people really obsessed with making sure that computer programs work right — that they don’t contain errors, that they do exactly what they’re going to do, and when a crisis happens that they don’t get overwhelmed, ” said Douglas.
Eric Moskowitz can be reached at eric.moskowitz@globe.com.