Mission Insignia | |
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Mission statistics | |
Mission name: | Apollo-Saturn 203 |
Call sign: | AS-203 |
Launch: | July 5, 1966 14:53:13 UTC Cape Canaveral Complex 37B |
Destroyed: | July 5, 1966 ~20:53:00 UTC |
Duration: | ~6 hours |
Number of orbits: |
4 |
Apogee: | 131.7 mi (212 km) |
Perigee: | 113.7 mi (183 km) |
Period: | 88.5 min |
Inclination | 31.94 deg |
Distance traveled: |
100,583 mi (161,872 km) |
Apogee mass: | 26,552 kg |
AS-203 |
AS-203 (orSA-203, sometimes informally called Apollo 2) was an unmanned flight of the Saturn IB rocket on July 5, 1966. It was designed as a test of the S-IVB second stage that would later be used by Apollo astronauts to boost them from Earth orbit to a trajectory towards the moon.
The purpose of the AS-203 flight was to investigate the effects of weightlessness on the liquid hydrogen fuel in the S-IVB second-stage tank. The lunar missions would use a modified version of the S-IVB as the third stage of the Saturn V launch vehicle. This called for the stage to fire briefly to put the spacecraft into a parking Earth orbit, before restarting the engine for flight to the Moon. In order to design this capability, engineers needed to learn how the liquid hydrogen would behave in the tank - would it settle in one place, or perhaps slosh violently?
In order to keep residual hydrogen in the tank on orbit, there would be no Apollo Command/Service Module payload as there was on AS-201 and AS-202. Also, the full load of liquid oxygen oxidizer was shorted slightly so that only the hydrogen would remain. The tank was equipped with 83 sensors and two TV cameras to record the fuel's behavior.
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 also the first launch of a Saturn IB from Pad 37B.
In the spring of 1966, the decision was made to launch AS-203 before AS-202, as the CSM that was to be flown on AS-202 was delayed. The S-IVB stage arrived at the Cape on 6 April 1966; the S-IB first stage arrived six days later, and the Instrument Unit came two days after that.
On April 19, technicians began to erect the booster at Pad 37B. Once again, the testing regime ran into problems that had plagued AS-201, including cracked solder joints in the printed-circuit boards, requiring over 8,000 to be replaced.
In June 1966, three Saturn rockets could be seen set up on various pads across the Cape: at Pad 39A was a full-size mock-up of the Saturn V; AS-202 was at Pad 34; and AS-203 was at 37B.
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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