Before John Glenn became the first American to orbit Earth, he made one unusual demand: that a mathematician named Katherine Johnson check the computer's numbers by hand, saying that if she agreed they were right, he was ready to fly

Before John Glenn became the first American to orbit Earth, he made one unusual demand: that a mathematician named Katherine Johnson check the computer's numbers by hand, saying that if she agreed they were right, he was ready to fly

“If she says they’re good,” Johnson recalled the astronaut saying, “then I’m ready to go.” That is how Katherine Johnson remembered John Glenn’s request, decades later. The “she” was Johnson herself. The numbers were the flight path for the mission that would make Glenn the first American to circle the planet. What strikes me about that line is what it quietly asserts. A man about to be strapped to a rocket trusted a person with a mechanical cal…