/sci/ - Science & Math

> Three Mariner probes were constructed for the mission, with two intended to fly and one as a spare in the event of a mission failure. The spacecraft was shipped to Cape Canaveral with their Atlas-Centaur boosters in December 1968 – January 1969 to begin pre-launch checkouts and testing.
>On February 14, Mariner 6 was undergoing a simulated countdown on LC-36A, electrical power running, but no propellant loaded in the booster. During the test run, an electrical relay in the Atlas malfunctioned and opened two valves in the pneumatic system which allowed helium pressure gas to escape from the booster's balloon skin.
>The Atlas began to crumple over, however two pad technicians quickly activated a manual override switch to close the valves and pump helium back in. Although Mariner 6 and its Centaur stage had been saved, the Atlas had sustained structural damage and could not be reused, so they were removed from the booster and placed atop Mariner 7's launch vehicle on the adjacent LC-36B, while a different Atlas was used for Mariner 7.
>NASA awarded the quick-thinking technicians, Bill McClure and Charles (Jack) Beverlin, an Exceptional Medal of Bravery for their courage in risking being crushed underneath the 124-foot rocket.
>In 2014, an escarpment on Mars which NASA'S Opportunity rover had recently visited was named the McClure-Beverlin Ridge in honor of the pair, who had since died.