The early 1960s saw many rocket launch failures in the United States, all involving unmanned spacecraft. The biggest — and costliest — destroyed an Atlas ICBM booster with a purpose-built Centaur second stage at Cape Canaveral on March 3, 1965. It was supposed to lift a mockup of the unmanned Surveyor lunar lander into space. Instead, it managed an altitude of about 10 feet before crashing back to earth in spectacular fashion.
The Atlas booster was notoriously thin-skinned, so the massive explosion didn’t come as a real surprise when its fuel tanks ruptured on impact. But the extensive damage to the launch pad meant NASA needed to find another launch location. Fortunately, the agency was building another pad nearby, and used it to successfully put another stack, AC-6, into action just five months later.
Ironically, the combination went on to become NASA’s most productive and successful line of launch vehicles over a span of 42 years, with 181 of 197 liftoffs putting unmanned satellites in earth orbit, solar orbit, and on their way to the moon.