Glenn wasn’t keen on putting his life in the hands of the computers that would be used to handle the mission on Earth, and wanted Katherine Johnson to check all the equations by hand to give him confidence they were right.
Katherine Johnson did trajectory analysis for America’s first human spaceflight, Alan Shepard’s mission Freedom 7 in 1961.
She also contributed to America’s first orbital spaceflight piloted by John Glenn.
She also worked on the space shuttle and Earth Resources Satellite.