Katherine Johnson checked John Glenn's orbit calculations by hand
Before John Glenn's historic spaceflight, NASA mathematician Katherine Johnson verified an IBM computer's trajectory calculations by hand to ensure his safe return.
Before astronaut John Glenn became the first American to orbit Earth, he insisted on one final check of his mission's critical calculations.
The computer's calculations
An IBM computer had calculated John Glenn's trajectory for his orbital flight. The machine had determined the precise path the spacecraft would follow and the timing for every maneuver. But Glenn wanted human verification before he trusted his life to those numbers.
Katherine Johnson's verification
Glenn wanted Katherine Johnson to check those calculations by hand. Johnson was a mathematician working at NASA, known for her exceptional skill with complex orbital mechanics. She took the computer's output and worked through the math herself, verifying each calculation manually.
She checked the numbers before Glenn's launch. Her work was meticulous, ensuring that every figure matched and every equation balanced. Her math showed when to fire the retrorockets, the crucial engines that would slow the spacecraft and allow it to return safely to Earth.
The successful mission
With Johnson's verification complete, Glenn launched, orbited Earth, and returned safely. The mission was a triumph for NASA and a pivotal moment in the space race. Johnson's hand calculations had confirmed what the computer predicted, giving Glenn the confidence he needed to make history.
