The legendary NASA mathematician Katherine Johnson died Monday at the age of 101, the U.S. space agency has announced. Johnson developed mathematical equations that were essential to NASA’s early efforts to send astronauts into space and then to the moon—and the principles discovered in her work remain at the core of manned space travel today. Her trailblazing career was portrayed by Taraji P. Henson in the Oscar-nominated 2016 film Hidden Figures, which told the story of the black women whose work at NASA went uncelebrated at the time but was integral during the Space Race. She wasn’t well-known by the public until President Barack Obama awarded her the Presidential Medal of Freedom—the country’s highest civilian honor—in 2015. Bill Barry, NASA’s chief historian, said of Johnson: “She had a singular intellect, curiosity and skill set in mathematics that allowed her to make many contributions, each of which might be considered worthy of a single lifetime.” He went on to say that Johnson’s work was “critical to the success of the early U.S. space programs.”