Friday, July 17, 2009

Apollo 2


AS-203 (or SA-203) was an unmanned flight Saturn IB launch vehicle. It is sometimes informally called Apollo 2.

Objectives

The main purpose of the AS-203 flight was to investigate the effects of weightlessness on the fuel in the S-IVB tank. The reason for this was that the S-IVB would be used by Apollo astronauts to boost them from Earth orbit to a trajectory towards the moon. Engineers wanted to see what the liquid hydrogen would do in the tank - settle in one place or maybe even slosh violently. The S-IVB tank was equipped with 83 sensors and two TV cameras to record what the fuel did.

Because this was an engineering flight, there was no Command Service Module (CSM). This was also the first flight of a new type of Instrument Unit that controlled the Saturn rockets during launch and the first launch of a Saturn IB from Pad 37B.

Flight

The rocket launched on the first attempt on July 5. The S-IVB and IU were inserted into a 188 km circular orbit.

It was found that the stage could restart and that the fuel behaved just as predicted. It was observed over four orbits and then the stage was pressurized to see how much stress it could stand. In the end this test exceeded the structural capabilities of the stage and it fragmented.

Despite the destruction of the stage, the mission was classified as a success, having achieved all of the mission objectives. In September Douglas Aircraft Company, who built the S-IVB, declared that the stage was operational and ready to send men to the Moon. Fragments of the first stage supposedly hit a German fishing vessel.

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