A test with nothing to lose but hardware
On the morning of 9 November 1967, the Saturn V rocket left its pad at the Kennedy Space Center in Florida for the first time. The mission, officially Apollo 4, carried no crew. Its purpose was to find out whether the largest rocket the United States had built would work, and whether the Apollo command module could survive returning to Earth at the speed it would have after a trip to the Moon.
It was the first launch from Launch Complex 39A, and it came less than ten months after the Apollo 1 fire had killed three astronauts and forced a rethink of how the programme operated. A good result was badly needed.
What the Saturn V was
The Saturn V stood about 110 metres (363 feet) tall with its spacecraft. It had three stages: the S-IC first stage, built by Boeing; the S-II second stage, built by North American Aviation; and the S-IVB third stage, built by Douglas. The first stage burned five F-1 engines, and at liftoff the rocket produced a thrust of several million pounds, far more than any previous American launcher. The design was led from NASA’s Marshall Space Flight Center, where Wernher von Braun directed the work.
Everything was large. Propellants were liquid oxygen with kerosene in the first stage, and liquid oxygen with liquid hydrogen in the upper two.
All-up testing
The most important decision behind Apollo 4 was not a piece of hardware but a method. Earlier rocket programmes had typically flown one stage at a time, adding live stages gradually. NASA’s manned spaceflight chief, George Mueller, pushed for what became known as all-up testing: fly the complete rocket on the first attempt. The reasoning was that the schedule left no room to do otherwise if the Moon landing was to happen before the end of the decade.
The approach was a gamble, because a failure would destroy a very expensive vehicle and set the programme back. Some engineers were nervous. Apollo 4 would show whether the gamble was justified.
The flight
The mission lasted a little under nine hours. After liftoff the first stage was jettisoned and the second stage took over, followed by the third stage, which placed the spacecraft in a low Earth orbit. In orbit, the S-IVB stage was shut down and then restarted, a step that mattered because a real lunar mission would require restarting the engine to leave Earth orbit.
The craft then used the spacecraft’s own engine to raise its path to a very high altitude, tens of thousands of kilometres out, and commanded the command module back toward the atmosphere. This produced a re-entry at roughly the speed of a returning lunar mission, around 11 kilometres per second, which tested the heat shield under realistic conditions. The module splashed down in the Pacific Ocean near Hawaii and was recovered.
The spacecraft was an early-type command module, not the redesigned version that crews would later use, and a test article stood in for the lunar module. It was the rocket and the heat shield that were under examination.
The sound of the launch
The launch was watched by many people and covered by television networks. Accounts of the day often mention how forcefully the noise and vibration reached observers at the press site several miles away, with reports of the broadcast studio shaking. Those accounts are widely repeated, and they give a sense of how unlike earlier launches this was, though exact details vary between tellers.
What the results meant
Apollo 4 was judged a success. The stages performed as planned, the S-IVB restarted, and the command module’s heat shield withstood the re-entry. NASA officials were reportedly delighted with how closely the flight matched expectations, and the result greatly raised confidence in the Moon schedule. Ground computing for such missions depended heavily on IBM mainframes, which processed the flood of telemetry as the flight unfolded.
The picture was not entirely clean. A second uncrewed Saturn V, Apollo 6, flew in April 1968 and suffered violent vibration in the first stage and engine problems in the upper stages. The troubles were studied and corrected, and the Saturn V’s next flight, Apollo 8 in December 1968, took astronauts to the Moon.
Why it mattered
A rocket of this size had been a source of doubt. Apollo 4 showed that the concept worked and that the all-up method was viable. In the larger space race, the Soviet Union’s own giant rocket, the N1, was still unflown, and the American lead on that front grew after Apollo 4.
The Saturn V went on to launch the Apollo crews to the Moon and, in 1973, the Skylab space station. Its first flight, on that November morning in 1967, was the first sign that the tools to reach the Moon existed. A year of setbacks ended with a hopeful result.