Toward these ends, Lt. Col. John Glenn (USMC) on February 20, 1962, became the first American to demonstrate that manned orbital spaceflight was both possible and survivable. And he amply proved how well humans could function in space, assuming manual control of his spacecraft when his thrusters malfunctioned. In the blockhouse that morning, Glenn’s backup, Scott Carpenter, had listened to the countdown and then to the thunderous Atlas engines. “Godspeed, John Glenn,” he said, as his friend vaulted into space. Glenn made three circuits of the planet aboard Friendship 7 (MA-6) in just under five hours.

Although not without incident, Glenn’s flight was a walloping success and a welcome boost of confidence for a nation, and a space agency, still playing catch-up with the Soviets. Click here for the NASA history of MA-6, and here for John Glenn’s website.)

Deke Slayton and Wally Schirra were the prime-alternate team for the follow-on flight, MA-7, then scheduled for an April 1962 launch.

NASA administrator James Webb had in the meantime, however, reopened “the Slayton case.”