File:Mercury Aurora-7 spacecraft clock.jpg

English: This is the Mercury Aurora-7 spacecraft clock that timed the mission for Scott Carpenter, the second American to orbit the Earth in 1962. It still runs today.

At T+0, this clock started clicking in the center of the cramped spacecraft's instrument panel — quite loudly as you can hear in my video — and it was a mission critical device for timing the spacecraft’s reentry into the Earth’s atmosphere for the planned splashdown location.

The "5 Min to Retrograde" telelight is mentioned by Carpenter in the voice transcript: “Okay, I'm going to fly-by-wire to Aux Damp, and now — attitudes do not agree. Five minutes to retrograde, light is on. I have a rate of descent, too, of about 10, 12 feet per second.”

Carpenter missed the clock and activated the retrorockets three seconds late; this delay, compounded by a malfunctioning pitch horizon scanner, forced Carpenter to control his reentry manually. As a consequence, Aurora 7 missed its landing area by 250 miles, and Carpenter was left to float alone in his life raft for nearly an hour before he was found. At Cape Canaveral, CBS veteran Walter Cronkite played up the drama by describing Mission Control’s repeated attempts to contact Aurora 7. “While thousands watch and pray,” Cronkite told his audience, “certainly here at Cape Canaveral, the silence is almost intolerable.”

Floating alone, Carpenter exited the capsule through the nose, the only astronaut to do so. He had to remove the instrument panel from the bulkhead, exposing a narrow egress tunnel where the two parachutes had resided.

After the flight, this clock was removed from the Mercury spacecraft and given to Carpenter in this custom display, signed by launch pad team leader Guenter Wendt. 61 years later, I bought it from the Carpenters, and reunited it with the Mercury Earth Path Indicator, a black box like this one that would have been next this clock in the center panel. I am trying to determine if it also flew on MA-7.

Three months prior, Carpenter was in the control center, as backup for MA-6, and he called out "Godspeed, John Glenn." Glenn felt a jolt as the rocket left the launch pad, replying: "Roger, liftoff, and the clock is running. We're under way." Here is the dramatic reenactment in The Right Stuff, with the clock reference being the first spoken words after launch