video for embedding at http://scitech.quickfound.net/astro/project_apollo.html The launch of Saturn 1B AS-203 on July 5, 1966, from Cape Canaveral Kennedy Space Center Launch Complex 37B. Wikipedia: "AS-203 (or SA-203) was an unmanned flight of the Saturn IB rocket on July 5, 1966. It carried no Apollo Command/Service Module spacecraft, as its purpose was to verify the design of the S-IVB rocket stage restart capability that would later be used in the Apollo program to boost astronauts from Earth orbit to a trajectory towards the Moon. It successfully achieved its objectives, but the stage was inadvertently destroyed after four orbits. "The purpose of the AS-203 flight was to investigate the effects of weightlessness on the liquid hydrogen fuel in the S-IVB-200 second-stage tank. The lunar missions would use a modified version of the S-IVB-500 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 verify that the anti-slosh measures designed to control the hydrogen's location in the tank were adequate, and that the fuel lines and engines could be kept at the proper temperatures to allow engine restart. "In order to keep residual propellants in the tanks on orbit, the Apollo Command/Service Module was replaced by an aerodynamic nose cone... The tank was equipped with 88 sensors and two TV cameras to record the fuel's behavior. "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 Cape Canaveral 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 100-nautical-mile (190 km; 120 mi) circular orbit. "The S-IVB design test objectives were carried out on the first two orbits, and the hydrogen was found to behave mostly as predicted, with sufficient control over its location and of engine temperatures required for restart. The next two orbits were used for extra experiments to obtain information of use in future cryogenic stage designs... "The closed fuel tank experiment involved pressurizing the hydrogen tank by closing its vents, while depressurizing the oxygen tank by allowing it to continue venting. It was expected that the pressure difference between the two tanks (measured as high as 39.4 pounds per square inch (272 kPa)) would collapse the common bulkhead separating them, as confirmed in a ground test. The rupture must have occurred during the two-minute loss of signal between the Manned Spacecraft Center and the Trinidad tracking station, where radar acquired the vehicle in multiple pieces, indicating an explosion had occurred. It is believed that a spark or impact must have ignited the propellants. "Despite the destruction of the stage, the mission was classified as a success, having achieved all of its primary objectives and validating the design concept of the restartable dash-500 version. In September Douglas Aircraft Company, who built the S-IVB, declared that the stage was operational and could be used on the Saturn V to send men to the Moon." http://en.wikipedia.org/wiki/AS-203 launch photo: http://mix.msfc.nasa.gov/IMAGES/HIGH/0100807.jpg more information: Results of the Second Saturn IB Launch Vehicle Test Flight AS-203 Sept 1966 http://www.scribd.com/doc/59689495/Results-of-the-Second-Saturn-IB-Launch-Vehicle-Test-Flight-AS-203 Evaluation of AS-203 low gravity orbital experiment 1967 http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680012073_1968012073.pdf Cryogenic Tank Modeling for the Saturn AS-203 Experiment 2006 http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060047496_2006249416.pdf This is the same video uploaded by NASA with letterboxing (black bars) removed and the aspect ratio corrected. NASA, Project Apollo, moon program, space program, Apollo program, Saturn, rocket, launch vehicle, H-1 engine, Saturn IB, Saturn 1B, Cape Canaveral, Kennedy Space Center, KSC

• published: 14 Sep 2011
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