The pilot of the first American orbital spaceflight had to lobby his bosses to bring a 35-millimeter camera he bought at a drugstore. This episode reconstructs John Glenn’s Mercury-Atlas 6 mission on February 20, 1962, from the months of scrubs over fuel leaks, gyroscopes, and cloud cover, through the broken hatch bolt that added 42 minutes on the pad, to the moment Scott Carpenter said Godspeed, John Glenn and a radio glitch kept Glenn from hearing it.

In orbit, Glenn reported a dust storm over Kano, saw the lights of Perth switched on for him, and tested the mysterious fireflies by banging on the capsule wall. Then a yaw thruster failed, forcing hours of manual fly-by-wire control that burned nearly 30 percent of his fuel. Meanwhile a sensor called Segment 51 suggested the heat shield was loose, and mission control chose to keep the retro package attached through reentry without telling Glenn why. We cover the flaming debris past his window, the falling-leaf oscillations as fuel ran out, the early parachute deployment, the reassuring clunk of the landing bag, and why the whole scare came down to a faulty microswitch.

• Why a 33 percent Atlas failure rate and a shark chaser in the survival kit defined the mission’s risk
• How Glenn and his family chose the name Friendship 7 as a Cold War message of peace
• How a stuck yaw thruster turned the astronaut from cargo into the mission’s essential failsafe
• The debate between Walter Williams and Chris Kraft over keeping the retro rockets on during reentry
• What the flight suggests about relying on automation versus human instinct in future deep-space missions