In honor of International Women’s Day this week, let’s highlight the work of Katherine Johnson, math teacher, NASA human computer, and inspiration for Margot Lee Shetterly’s recent book and the feature film, Hidden Figures. What does it mean to be a “human computer” for NASA? How are launch dates and flight paths for spacecraft determined?
Katherine Johnson
By the age of 10, Katherine had taken all of the classes her hometown of White Sulfur Springs, West Virginia had to offer black students at the time, the equivalent of an eighth grade education. So her father moved the family over 100 miles away so that she could attend high school, and she later graduated from West Virginia State College (now West Virginia State University) with degrees in mathematics and French at the age of 18.
Her exceptional schooling record did not stop there. In 1939, along with two male students, she then bravely became the first to desegregate the graduate program at West Virginia University. However, she only stayed in the program for less than a year. By some accounts, she left to start a family, while others suggest the environment was not as welcoming as her undergraduate experience.
Johnson worked as a public school teacher of mathematics, French, and music in Worked as teacher of math and French and music until she earned a spot as a “human computer” in 1953 at what is now the Langley Research Center in Hampton. There she worked alongside and under Mary Jackson and Dorothy Vaughn, whose efforts are also highlighted in Hidden Figures.
Katherine soon moved to Langley’s Flight Research Division where she worked on complex mathematical problems like investigating a plane crash caused by wake turbulence. National focus soon shifted quickly, however, when the Soviet satellite Sputnik was launched in 1957 amidst the Cold War between the US and the USSR. The US responded to what NASA refers to as “the Sputnik crisis” by creating the National Aeronautics and Space Administration, and the space race was on. Katherine Johnson was among the first ~8,000 NASA employees.
Calculating Orbital Trajectories Is Women’s Work
In the early years of NASA, the challenging work of complex, multivariable computations, work which required incredible focus and attention to detail, was assigned to groups of women known as “human computers”. In fact, as the first electronic computers were being introduced, programming the machines was considered women’s work.
One such computation was determining the most efficient path for spacecraft – a path that used the least amount of fuel, avoided other solar system bodies while in flight, and ended with a landing in a pre-designated location. You don’t have to have taken an orbital mechanics class to know these equations are not simple. The Earth’s atmosphere provides drag. The weight of your rocket changes as you burn fuel to leave that atmosphere. The Earth is rotating. You don’t want to hit the Moon, but the Moon keeps moving! Thanks to all of these complications, and many others, the related computations generally cannot be done analytically, but instead must be done numerically. For a visual, check out this video of the Voyager flight paths as they avoid running into solar system bodies while still using them for the occasional gravity assist.
In 1961, only a few years after NASA’s formation, Alan Shepard became the first American to travel into space (the second person after Soviet cosmonaut Yuri Gagarin) as part of the Mercury-Redstone 3 mission, and the path for his flight was calculated by Katherine Johnson. In 1962, John Glenn became the first American to orbit the Earth on board the Friendship 7 spacecraft, a mission with a trajectory significantly more difficult to calculate.
At the time, orbital flight path determination was so complex that a worldwide communications network that linked tracking stations around the world to computers in Washington, D.C. and Cape Canaveral, had been developed to control the trajectory of Glenn’s Friendship 7 mission capsule. However, astronauts generally did not trust these electronic calculators, machines known to be “prone to hiccups and blackouts”, with their lives, and John Glenn reportedly asked that the calculations be checked by Katherine Johnson and her colleagues before he would trust them.
The success of Alan Shepard’s and John Glenn’s missions, which relied heavily on Katherine Johnson’s work, served as a turning point in the space race between the US and the USSR. During her tenure at NASA, Katherine Johnson also provided trajectory work for the Lunar Orbiter program that mapped the surface of the Moon in preparation for the Moon landing a few years later. She then calculated the orbital trajectory for the Apollo 11 mission that famously brought astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins to the Moon (and back!), which remains the farthest humans have ever traveled in space. After an exploding oxygen tank prevented the Apollo 13 mission from reaching the Moon, Johnson aided in determining the orbital trajectory to bring the astronauts on board back to safety.
Electronic Over Human Computation
Although NASA now relies on electronic over human computation, one of the first human computers hired by NASA to compute trajectories for rocket launches still works at the Jet Propulsion Laboratory as a software tester and subsystem engineer. Sue Finley is the longest-serving female NASA employee and at the age of 80, is a member of the team on NASA’s Juno mission to Jupiter.
These tools allow for the creation of flight plans in a matter of minutes – calculations that would take days of calculations by hand.
Now NASA relies on tools like their Horizons ephemeris guide which tracks the positions of large solar system bodies to high precision and the General Mission Analysis Tool (or GMAT), a modeling program that optimizes orbital trajectories. These tools allow for the creation of flight plans in a matter of minutes – calculations that would take days of calculations by hand. GMAT is also used by the Air Force Research Lab for problems like simulating collision avoidance among satellites and people like you! GMAT is open source code and has been downloaded over 49,000 times.
Last year NASA also announced the introduction of the Evolutionary Mission Trajectory Generator which not only calculates flight paths from the equations of orbital mechanics, but also takes into account spacecraft design like the type of launch vehicle and propellant tanks used to satisfy different performance criteria. Since the design of spacecraft clearly affects its trajectory, this added flexibility will allow for more efficient calculations, as well as more efficient spacecraft.
Honors for Katherine Johnson
Thirty years after her retirement in 1986, Johnson’s story, and the work of many other African American women computers, were brought into the spotlight by Margot Lee Shetterly’s book Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race, and Katherine Johnson’s contributions were hidden no longer. President Barack Obama awarded her the Presidential Medal of Freedom in 2015, the highest civilian honor in the US, and in May 2016, NASA opened the $30 million Katherine G. Johnson Computational Research Facility at Langley.
In a piece for Vanity Fair, former NASA Administrator Charles Bolden stated that, “With a slide rule and a pencil, Katherine advanced the cause of human rights and the frontier of human achievement at the same time.” The movie Hidden Figures, based off of Shetterly’s book, has brought in more than $158 million at the box office and is changing the optics on not only what it looks like to be a NASA engineer, but also what it takes for a black woman to get there. In the movie’s trailer, Janelle Monae as human computer Mary Jackson is asked, “If you were a white male, would you wish to be an engineer?” And she responds, “I wouldn’t have to. I’d already be one.”
Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.