Apollo 5

Apollo 5 was an unmanned test flight within the Apollo program. The main goal was to test the Lunar Module (LM), which was tested in space for the first time. The internal project designation was AS-204.

The launch vehicle was the Saturn IB, which had also been used for the ground test in which the three Apollo 1 astronauts had lost their lives. The rocket had remained undamaged in the fire at that time and could still be used. The LM-1 was steerable and maneuverable, but no landing legs were mounted. Since, in contrast to manned launches, no rescue rocket was needed, the Saturn IB was only 55 meters high. At the top there was a cone instead of an Apollo spacecraft which was dropped before the tests.

The launch took place on January 22, 1968, and the rocket worked flawlessly. In a low-Earth orbit, the lunar module was separated from the second stage. Then the engine of the descent stage should bring the LM into a higher orbit. When it was fired, it did not burn for the planned 39 seconds, but was prematurely shut down by the on-board computer after four seconds. The fault was in a computer program that stops the engine if the desired parameters are not reached quickly enough. The cause was that shortly before the start, due to the suspicion of a leaking control valve, the procedure for the fuel supply was changed. The programmers were not informed of this change, which caused a delay in the build-up of thrust and would have required an adjustment in the waiting time before the parameters could be tested. Since the engine did not achieve the desired parameters after the programmed time, they used the control program for bench testing. The two further firings then proceeded successfully. After separation from the descent stage, the ascent stage also completed a successful engine test.

After the mission was completed, the two parts of the lunar module remained in Earth orbit for some time and burned up independently in the atmosphere, the ascent stage on January 24 and the descent stage on February 12, 1968.