Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race

by Margot Lee Shetterly

At 9:47 a.m. EST, the Atlas rocket boosted Friendship 7 into orbit like a champion archer hitting a bull’s-eye. The insertion was so good that the ground controllers cleared Glenn for seven orbits. But then, during the first orbit, the capsule’s automatic control system began to act up, causing the capsule to pull back and forth like a badly aligned car. The problem was relatively minor; Glenn smoothed it out by switching the system to manual, keeping the capsule in its correct position the same way he would have flown a plane. At the end of the second orbit, an indicator in the capsule suggested that the all-important heat shield was loose. Without that firewall, there was nothing standing between the astronaut and the 3,000-degree Fahrenheit temperatures—almost as hot as the surface of the Sun—that would build up around the capsule as it passed back through the atmosphere. From Mission Control came an executive decision: at the end of the third orbit, after the retrorockets were to be fired, Glenn was to keep the rocket pack attached to the craft rather than jettisoning it as was standard procedure. The retropack, it was hoped, would keep the potentially loose heat shield in place.