In 1962, John Glenn sat in his capsule waiting for his rocket engines to light-up and lift him to space. But first, he insisted that Katherine Johnson double-check the electronic computer’s trajectory calculations. While that’s the dramatic version of events given in the recent movie, Hidden Figures, the reality isn’t very far off. Glenn wasn’t sitting on the launchpad at the time, but during the weeks prior to launch, he did insist that Johnson double-check the computer’s calculations.

So who is this woman who played an important but largely unknown part of such a well-known historical event? During her long life, she was a wife, a mother, an African-American, a teacher, and a human computer, a term rarely used these days. Her calculations played a part in much of early spaceflight and in 2015, she was awarded the Presidential Medal of Freedom by President Obama. She also has a building named after her at the Langley Research Center in Hampton, Virginia.

Off Like A Rocket

She was born Katherine Coleman on August 26, 1918, in White Sulphur Springs, Greenbrier County, West Virginia. Her mother was a teacher and her father was a lumberman, farmer, handyman and worked at a hotel. Due to her mother’s influence, she could read at the age of four. She enjoyed counting everything and had a gift for numbers. Their county didn’t offer public schooling for African-Americans past grade eight and so her father took the family the 130 miles (210 km) to Institute, West Virginia where she could attend high school. They spent the school years in Institute and the summers in White Sulphur Springs. She was ten years old at the time and graduated at fourteen.

The school was part of the West Virginia State College, a historically black college, and so she did her college there, taking every math course available. She had multiple mentors, including W. W. Schiefflin Claytor, only the third African-American to get a Ph.D. in math. At one point he said, “You’d make a good research mathematician and I’m going to see that you’re prepared.” This sort of encouragement was something she received a lot of during her upbringing. At the age of 18, she graduated with highest honors with degrees in Mathematics and French.

Mathematician To The Stars

She desired a career as a research mathematician but at first, could find only teaching jobs. Then in 1952, a relative mentioned that NACA (the predecessor to NASA) was looking for mathematicians. It turned out that NACA’s Langley Memorial Aeronautical Laboratory, in Hampton, Virginia needed mathematicians for their Guidance and Navigation Department. She began working for them in 1953.

She first worked in a pool of women doing math calculations, mainly analyzing black box data from flight tests but also doing other mathematical jobs. She referred to the women as the “computers who wore skirts”. Two weeks into the work she moved over to the Flight Research Division’s Guidance and Control Division and never returned.

In 1957, the Russians launched Sputnik 1, the world’s first satellite, into space. As part of the race to catch up, in 1958, NACA became NASA. The group she was in became the Space Task Force, tasked with figuring out how to get a human into space and back. As she put it:

We wrote our own textbook, because there was no other text about space. We just started from what we knew. We had to go back to geometry and figure all of this stuff out. Inasmuch as I was in at the beginning, I was one of those lucky people.

Computing The First American In Space

She did trajectory analysis for Alan Shepard’s May 1961 Freedom 7 mission, part of the Project Mercury flights and the first time an American went to space. Launching from Cape Canaveral, Florida, it was a 15-minute suborbital flight. The trajectory was a parabola peaking at 187.5 km (116.5 miles) up and traveling a downrange distance of 487.3 km (303 miles), splashing down in the Atlantic. The goals were to test how well Shepard handled the high g-forces during launch and the heat of atmospheric re-entry.

The calculations involved basic geometry. In Johnson’s words:

The early trajectory was a parabola, and it was easy to predict where it would be at any point. Early on, when they said they wanted the capsule to come down at a certain place, they were trying to compute when it should start. I said, ‘Let me do it. You tell me when you want it and where you want it to land, and I’ll do it backwards and tell you when to take off.’

The “Girl” Who Did It

John Glenn’s Friendship 7 mission in February 1962 involved orbiting the Earth three times. That added the complexity of the Earth’s gravitational pull and so NASA used a digital computer, the IBM 7090, for the calculations. It did the orbital calculations to control the trajectory of the capsule from launch to splashdown. But the computer was prone to hiccups and blackouts, and so the astronauts were wary of it.

It’s not known exactly when Glenn made the following request, but sometime in the week’s prior to the launch, referring to Johnson he said:

Get the girl to do it. [All the women working at the time were referred to as “girls”.] I want this human computer to check the output of the electronic computer, and if she says they’re good, you know, I’m good to go as part of one of my pre-flight checklists.

With the help of her desktop calculator, she then did the same computations as the computer. Depending on the source, the calculations took either a day and a half or three days, but she got the exact same numbers as the digital computer. The rest is history.

Apollo 11 And After

She was most proud of the success of the Apollo 11 mission wherein she was part of the team which computed the path to get to and from the Moon. To start calculations, in principle all they needed to know was where you’d launch from on the Earth and where the Moon would be. While most people were concerned about getting there, she was more concerned about the return. Watching the events on TV during the mission, she recalled thinking that if the astronauts were off by a degree then they would fail to orbit the Earth. She was hoping that they’d gotten the calculations right.

She says her greatest contribution to space travel was her help with calculations for syncing up the Apollo lunar lander with the command module in lunar orbit.

Her work didn’t end there. She also helped with contingency procedures for Apollo 13 when it experienced its malfunction while in space. She worked on the Space Shuttle, the Earth Resources Satellite, and on plans for a Mars mission.

She retired in 1986.

Segregation And Honors

Racial segregation was still very much present in the US south at the time. Johnson experienced it throughout her life but never let it get in her way. In the movie, Hidden Figures, she has to walk a long distance to use the colored women’s bathroom while working at Langley. In fact, it was Mary Jackson, a NASA engineer also featured in the movie who did so. Johnson instead used the unlabeled white women’s bathroom, at first not knowing about the segregation. When she found out, she just ignored it.

She also experienced obstacles as a woman. She insisted on attending meetings that were normally for men only. Womens’ names were not included as co-authors on reports until her’s became the first — the first of 26 which she would co-author throughout her career.

Of that career, she says “I found what I was looking for at Langley. This was what a research mathematician did. I went to work every day for 33 years happy.”

Among the honors she’s received, on November 24, 2015, President Obama awarded her the Presidential Medal of Freedom and on May 5, 2016, NASA named a new 40,000 square foot building at the Langley Research Center the Katherine G. Johnson Computational Research Facility.

She’ll be celebrating her 100th birthday on August 26, 2018.

Here’s a short video interview that does a good job summing up her attitude toward math, work and life: “Do your best, but like it, and then you will do your best.”