Katherine Johnson, the mathematician whose calculations influenced some of the most important missions of the space age, on Friday helped Nasa open a new research and development facility that bears her name.

The 99-year-old cut the ribbon for the Katherine G Johnson Computational Research Facility at the Langley research center in Hampton, Virginia, where she was honored as a trailblazing “human computer”.

In a pre-taped video message, Johnson laughed when asked how she felt about a building being named in her honor.

“You want my honest answer? I think they’re crazy,” she said. “I was excited at something new, always liked something new, but give credit to everybody who helped. I didn’t do anything alone but try to go to the root of the question and succeeded there.”

In an extraordinary career, Johnson defied racial and gender constraints and was involved with many of the greatest achievements in space.

“Today all of these things seem inevitable,” said Margot Lee Shetterly, the author of Hidden Figures, which profiles Johnson and her fellow “human computers” and was made into a film last year. “But without her past full of diverging roads and choices that made all the difference we would not be standing on the brink of this future.”

Johnson was born in 1918 in White Sulphur Springs, West Virginia, the youngest child of farmer and a teacher. From an early age, she showed signs of prodigious ability.

“I counted the steps,” she said in an oral history archived by the National Visionary Leadership Project. “I counted the plates that I washed. And I knew how many steps there were from our house to church.”

Her county did not offer public schooling for black students after the eighth grade, so she had to relocate to Institute, West Virginia, to continue her education through high school. She graduated West Virginia State College at 14, the age at which most students begin.

She whipped through every math course her college had to offer and graduated, still a teenager, with degrees in mathematics and French. In 1939, she was one of three black students – and the only woman – to integrate the state’s graduate schools, enrolling in a math program at West Virginia University.

For more than a decade, Johnson taught in segregated schools. Then a relative told her about a job opening at the National Advisory Committee for Aeronautics or Naca, a precursor of Nasa.

In 1953, Johnson joined an all-black team of “human computers”, her mathematical acuity earning her a place on the main research team, where she would produce calculations for the 1961 flight trajectory of Alan Shepard, the first American in space. She also verified the calculation produced by a computer for John Glenn’s 1962 orbit, and for the 1969 Apollo 11 trajectory to the moon.

“That’s the way it was,” she said in the oral history. “They just said, ‘If she says it’s right, it’s right’ because the guys didn’t do the work. I did it.”

In 2015, Barack Obama awarded Johnson the presidential medal of freedom, the highest US civilian honor, calling her a “pioneer who broke the barriers of race and gender, showing generations of young people that everyone can excel at math and science and reach for the stars”.

Obama joked: “If you think your job is pressure-packed, hers meant that forgetting to carry the one might send somebody floating off into the solar system.”

On Friday, Shetterly said: “We are living in a present that they willed into existence with their pencils, their slide rules, their mechanical calculating machines and, of course, their brilliant minds.”

Johnson’s story – and the largely untold history of contributions by black women during the space race – was told on the big screen last year. Hidden Figures stars among others Taraji P Henson (who plays Johnson), Octavia Spencer and Janelle Monáe.

The movie, mostly set in 1961 and 1962, highlights the indignities endured by black Nasa employees despite the agency’s reliance on them. In the movie, after Johnson joins the main research team, she is forced to drink coffee from a pot labeled “colored” and walk half a mile to use a restroom for “colored” women.

In the video played at Friday’s ceremony, Johnson advised aspiring scientists and mathematicians to find a career that they enjoy and credited her success simply to an enthusiasm for solving complex equations.

“I liked work,” Johnson said. “I liked the stars and the stories we were telling. And it was a joy to contribute to the literature that was going to be coming out. But little did I think it would go this far.”