When Katherine Johnson began working at the National Advisory Committee for Aeronautics in 1953, she was classified as “subprofessional”, not far outranking a secretary or janitor.
Hers was a labour not of scheduling or cleaning but rather of mathematics: using a slide rule or calculator in complex calculations to check the work of her superiors – engineers who, unlike her, were white and male. Her title, poached by the technology that would soon make the services of many of her colleagues obsolete, was “computer”.
Johnson, who has died aged 101, went on to develop equations that helped Naca and its successor, Nasa, send astronauts into orbit and, later, to the moon. In 26 signed reports for the space agency, and in many more papers that bore others’ signatures on her work, she codified mathematical principles that remain at the core of human space travel.
She was not the first black woman to work as a Nasa mathematician, nor the first to write a research report for the agency, but Johnson was eventually recognised as a trailblazer for women and African Americans in the newly created field of spaceflight.
Like most backstage members of the space programme, Johnson was overshadowed in the popular imagination by the life-risking astronauts whose flights she calculated, and to a lesser extent by the department heads under whom she served.
She did not command mainstream attention until president Barack Obama awarded her the Presidential Medal of Freedom, the US’s highest civilian honour, in 2015. The next year, her research was celebrated in the bestselling book Hidden Figures by Margot Lee Shetterly and the Oscar-nominated film adaptation.
A maths prodigy from West Virginia who said she “counted everything” as a child – “the steps to the road, the steps up to church, the number of dishes and silverware I washed” – Johnson worked as a schoolteacher before being hired as a computer at Naca’s flight research division, based at Langley Research Centre in Hampton, Virginia.
The agency was established in 1915 and began enlisting white women to work as computers 20 years later. Black computers, assigned mainly to segregated facilities, were first hired during the labour shortage of the Second World War. Johnson was one of about 100 computers, roughly one-third of whom were black, when she joined Naca.
Johnson had a bachelor’s degree in mathematics and spent her early career studying data from plane crashes, helping to devise air safety standards at a time when the agency’s central concern was aviation. Then in October 1957 the launch of the Soviet satellite Sputnik thrust the space race into full tilt.
Johnson and dozens of colleagues wrote a 600-page technical report titled Notes on Space Technology, outlining the mathematical underpinnings of spaceflight, from rocket propulsion to orbital mechanics and heat protection.
One of rocket science’s most vexing challenges, they soon realised, was calculating flight trajectories to ensure that astronauts returned safely to Earth, splashing down in the ocean reasonably close to a navy vessel waiting to pluck them from the water.
For astronauts such as Alan Shepard, who became the first American in space when Freedom 7 launched on 5 May 1961, the maths was relatively straightforward. Shepard’s craft rose and fell, like a champagne cork, without entering orbit.
Calculating the trajectory for an orbital flight, such as the one to be undertaken by marine pilot John Glenn in 1962, was more complicated, but Johnson’s findings, outlined in a 1960 paper she wrote with engineer Ted Skopinski, enabled engineers to determine exactly when to launch a spacecraft and when to begin its re-entry. The paper marked the first time a woman wrote a technical report in Nasa’s elite flight research division.
Johnson’s handwritten calculations were said to have been more trusted than those performed by mainframe computers. A short time before Glenn launched into space and became the first American astronaut to orbit the Earth, he asked engineers to get Johnson to check the numbers.
In a subsequent report, Johnson took her calculations one step further, working with several colleagues to determine how a spacecraft could move in and out of a planetary body’s orbit. Her formulas were crucial to the success of the Apollo lunar programme and are still in use today.
Katherine Coleman was born in White Sulphur Springs, West Virginia, in 1918. Her mother was a former teacher. She credited her proclivity for mathematics to her father, a farmer who had worked in the lumber industry and could quickly calculate the number of boards a tree could produce.
By 10, Katherine had finished all the coursework offered at her town’s two-room schoolhouse. Joined by her mother and her three older siblings, she moved to Institute, a suburb of the state capital, to attend the laboratory school of West Virginia State College while her father remained at home to support the family.
Johnson went on to study at West Virginia State, a historically black college, with plans to major in French and English and become a teacher. An African American mathematics professor persuaded her to change fields.
After graduating in 1937, at 18, she taught at a segregated elementary school. Three years later she was one of three black students selected to integrate West Virginia University’s graduate programmes. She dropped out of her master’s in mathematics programme after one semester to start a family. She later returned to teaching, in West Virginia, before a brother-in-law suggested she apply for a computer position at Langley.
Here she performed calculations that determined the precise moment at which the Apollo lunar lander could leave the moon’s surface to return to the command module, which remained in orbit high above. She also contributed to Nasa’s space shuttle and Earth satellite programmes. She retired in 1986.
Her first husband James Goble, a teacher, died in 1956; her second husband James Johnson, an army artillery officer whom she married in 1959, died in 2019. She is survived by two daughters. A third daughter predeceased her.
Katherine Johnson, mathematician, born 26 August 1918, died 24 February 2020
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