“Wielding little more than a pencil, a slide rule and one of the finest mathematical minds in the country, Mrs. Johnson, who died at 101 on Monday at a retirement home in Newport News, Va., calculated the precise trajectories that would let Apollo 11 land on the moon in 1969 and, after Neil Armstrong’s history-making moonwalk, let it return to Earth.” Katherine Johnson Dies at 101; Mathematician Broke Barriers at NASA.