Katherine Johnson

Katherine Johnson: the ‘virtual computer’ who took man into space

Image credit: Nasa

A brilliant mathematician and physicist, Katherine Johnson was key to getting man on the Moon and became a high-flyer at a world-famous space agency, against all odds.

Sixty years after the first artificial satellite went into space, I thought it might be nice to look at one of the navigational computers that made orbital and manned spaceflight possible. Her name was Katherine Johnson.

Johnson was an unlikely computer. Firstly, she was human. More surprisingly, she managed to get that position with what 1950s USA called ‘profound handicaps’ – she was female and African-American.

Born in 1918, her early education wasn’t promising, as school in her county ended at eighth grade for African-American children. Yet Johnson was a superb mathematician and found a high school that would take her, which she followed up with a summa cum laude degree in mathematics and French, by which time she was still only 18.

However, opportunities for an African-American female mathematician were limited, to say the least, so she became a teacher until in 1953 her sister mentioned that the National Advisory Committee for Aeronautics, the forerunner of Nasa, was hiring African-American women in its Guidance and Navigation Department.

After a year of effort, Johnson became what she called a ‘virtual computer’. She was part of the West Area Computing Unit, an all-African-American, all-female group of mathematicians at the Langley Research Center. Her group analysed aircraft’s black-​box recorders and modelled the mechanics and geometry of flight and spaceflight as America attempted to compete with the Soviet Union to colonise the final frontier of space.

It was a profoundly far-sighted unit, there being few other organisations that would hire women for complex engineering-based work, let alone African-American women. Even in this liberal atmosphere, the unit was still subject to notorious ‘Jim Crow laws’, which required that African-Americans have separate canteens and toilets from their white counterparts.

Thankfully, necessity is the mother of invention and ability mattered much more at Nasa, so Johnson was seconded to Langley’s prestigious Flight Research Division, until then an all-male operation. Although this was meant to be temporary, she soon made herself invaluable and, as she later said: “They forgot to return me to the pool.”

At this time, there were still no electronic computers in Nasa so all hugely complex trajectory calculations (and hence launch windows) planned for early manned spaceflights had to be performed by hand. That was Johnson’s forte. It was she who calculated the launch window for Alan Shepard’s first sub-orbital flight on 5 May 1961, when he became only the second person in space. As she put it: “I’d ask (another section at Nasa), ‘Where do you want (the astronauts) to come down?’ They’d tell me the spot and I’d work backwards.”

By 1962, electro-mechanical computers were appearing at Nasa. One of their first jobs was to calculate the trajectory and launch window for John Glenn’s orbital flight of 1962, the first by a US astronaut. However, Glenn wasn’t happy to entrust his life to a mechanical computer and demanded that Johnson verify the figures.

Johnson’s job became vital, not just in her calculations, but in giving staff the confidence in electronic computer power that was to be necessary if manned spaceflight was to become routine. Even as electronic computers took the lead in planning trajectories, there remained a need for humans skilled in mathematical flight mechanics to check figures and plan for the unthinkable. So Johnson began calculating backup positions for spaceships in trouble and provided starcharts and plots to enable astronauts to navigate back to Earth if their computerised systems failed.

She also continued to calculate the most sophisticated flight trajectories, though when Neil Armstrong set foot on the Moon in 1969, there was less applause for the African-American woman who had guided him there. In fact, she wasn’t even at Mission Control. She did at least receive a commemorative flag that had flown with the Apollo 11 crew.

Johnson continued to work at Nasa until 1986, making the contingency calculations that helped ensure the safe return of the ill-fated Apollo 13, and worked on the Space Shuttle programme. During that time, the power of navigational computers grew exponentially. They are now an everyday part of our lives, but it was Katherine Johnson who taught us to trust them.

‘Hidden Figures’, a film based on Johnson, Mary Jackson and Dorothy Vaughan, is out now. E&T attended the London preview and found many parallels with their story and that of women today and the low female representation in STEM subjects and related employment.

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