Katherine Johnson (1918- )

An African-American mathematician whose calculations of orbital mechanics as a NASA employee were critical to the success of the first and subsequent U.S. manned spaceflights. During her 35-year career at NASA and its pre- decessor, she earned a reputation for mastering complex manual calculations. She calculated trajectories, launch windows, & emergency return paths for Projects Mercury and Apollo.
She also worked on the Space Shuttle program as well as work for a Mars mission.