Katherine Johnson, a pioneering NASA mathematician, died Monday at the age of 101. Johnson is celebrated for helping send Americans into orbit and to the moon.

NASA tweeted about Johnson's death, saying "we celebrate her 101 years of life and honor her legacy of excellence that broke down racial and social barriers."

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Johnson's achievements didn't receive mainstream attention until President Obama recognized her contributions in 2015 with the Presidential Medal of Freedom, America's highest civilian honor.

"In her 33 years at NASA, Katherine was a pioneer who broke the barriers of race and gender, showing generations of young people that everyone can excel in math and science and reach for the stars," Obama said during the ceremony.

The next year, Johnson was one of three black women at NASA whose story was told in the movie Hidden Figures, starring Taraji P. Henson, who played Johnson.

Johnson was one of three black students chosen to integrate West Virginia's graduate schools in 1939. After one semester at West Virginia University, Johnson left to start a family. In 1952, a family member told her that the National Advisory Committee for Aeronautics' (NASA's predecessor) Langley laboratory was hiring for its all-black computing section. In the summer of 1953, Johnson began work at Langley and spent the next four years analyzing flight test data.

Johnson would go on to contribute her skills to some of the country's most pivotal space missions, including America's first human spaceflight in 1961 and astronaut John Glenn's orbit around Earth in 1962. Glenn specifically asked for Johnson (saying "get that girl") to double check the orbital equations that would control the capsule's trajectory and were already programmed into computers. Glenn and the other astronauts did not trust these computers as they "were prone to hiccups and blackouts," according to NASA. Instead, he relied on Johnson to hand-check the calculations. "If she says they're good," Johnson remembered Glenn saying, "then I'm ready to go."

Johnson worked at Langley for 33 years, retiring in 1986.

As news broke of Johnson's death, people on Twitter shared what she meant to them.

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As Black History Month wraps up, remember this beloved figure, who is no longer hidden.