Katherine Johnson, NASA mathematician, has died at 101
"Wielding little more than a pencil, a slide rule and one of the finest mathematical minds in the country, Mrs. Johnson, whose death at 101 was announced on Monday by NASA, 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."The quality of work, done by hand, is just staggering when you think of the consequences that could have transpired if mistakes had been made.