AS-203 (also known as SA-203) was an uncrewed flight of the Saturn IB rocket on July 5, 1966. It carried no command and service module, 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 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-200, 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.[2]
In order to keep residual propellants in the tanks on orbit, there would be no command and service module payload as there was on AS-201 and AS-202. This was replaced by an aerodynamic nose cone. Also, the full load of liquid oxygenoxidizer was shorted slightly so that the amount of hydrogen remaining would approximate that of the Saturn V parking orbit.[2] The tank was equipped with 88 sensors and two TV cameras to record the fuel's behavior.
This was also the first launch of a Saturn IB from Pad 37B.
Preparationedit
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 Kennedy 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 regimen ran into problems that had plagued AS-201, including cracked solder joints in the printed-circuit boards, requiring over 8,000[clarification needed] to be replaced.
Flightedit
The rocket launched on the first attempt on July 5. The S-IVB and Instrument Unit (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 for use in future cryogenic stage designs. These included a free-coast experiment to observe and control the negative acceleration of the fuel caused by the small amount of aerodynamic drag on the vehicle; a rapid fuel tank depressurization test; and a closed fuel tank pressurization test.
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 happened in a ground test. The rupture occurred during the two-minute loss of signal between the Manned Spacecraft Center and the Trinidadtracking station. The Trinidad radar image indicated the vehicle was in multiple pieces, and telemetry was never re-acquired. NASA concluded that a spark or impact must have ignited the propellants, causing an explosion.
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 S-IVB-500 version. In September Douglas Aircraft Company, which built the S-IVB, declared that the design was ready for use on the Saturn V to send men to the Moon.
Moonport: A History of Apollo Launch Facilities and Operations March 18, 2011, at the Wayback Machine
Chariots for Apollo: A History of Manned Lunar Spacecraft October 20, 2015, at the Wayback Machine
January 01, 1970
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This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources AS 203 news newspapers books scholar JSTOR August 2010 Learn how and when to remove this message AS 203 also known as SA 203 was an uncrewed flight of the Saturn IB rocket on July 5 1966 It carried no command and service module 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 achieved its objectives but the stage was inadvertently destroyed after four orbits AS 203Launch of AS 203Mission typeLaunch vehicle developmentOperatorNASACOSPAR ID1966 059ASATCAT no 2289Mission duration 6 hoursDistance travelled161 900 kilometers 87 400 nmi Orbits completed4Spacecraft propertiesSpacecraftNoneStart of missionLaunch dateJuly 5 1966 14 53 13 1966 07 05UTC14 53 13Z UTCRocketSaturn IB SA 203Launch siteCape Kennedy LC 37BEnd of missionDestroyedJuly 5 1966 1966 07 06 Orbital parametersReference systemGeocentricRegimeLow Earth orbitPerigee altitude184 kilometers 99 nmi Apogee altitude214 kilometers 116 nmi Inclination31 9 degreesPeriod88 47 minutesEpochJuly 5 1966 1 Apollo program AS 201AS 202 Contents 1 Objectives 2 Preparation 3 Flight 4 References 5 External linksObjectives editThe 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 200 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 2 In order to keep residual propellants in the tanks on orbit there would be no command and service module payload as there was on AS 201 and AS 202 This was replaced by an aerodynamic nose cone Also the full load of liquid oxygen oxidizer was shorted slightly so that the amount of hydrogen remaining would approximate that of the Saturn V parking orbit 2 The tank was equipped with 88 sensors and two TV cameras to record the fuel s behavior This was also the first launch of a Saturn IB from Pad 37B Preparation editIn 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 Kennedy 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 regimen ran into problems that had plagued AS 201 including cracked solder joints in the printed circuit boards requiring over 8 000 clarification needed to be replaced Flight editThe rocket launched on the first attempt on July 5 The S IVB and Instrument Unit 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 for use in future cryogenic stage designs These included a free coast experiment to observe and control the negative acceleration of the fuel caused by the small amount of aerodynamic drag on the vehicle a rapid fuel tank depressurization test and a closed fuel tank pressurization test 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 happened in a ground test The rupture occurred during the two minute loss of signal between the Manned Spacecraft Center and the Trinidad tracking station The Trinidad radar image indicated the vehicle was in multiple pieces and telemetry was never re acquired NASA concluded that a spark or impact must have ignited the propellants causing an explosion 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 S IVB 500 version In September Douglas Aircraft Company which built the S IVB declared that the design was ready for use on the Saturn V to send men to the Moon References edit nbsp This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration McDowell Jonathan SATCAT Jonathan s Space Pages Retrieved March 23 2014 a b Evaluation of AS 203 Low Gravity Orbital Experiment PDF NASA January 13 1967External links edit nbsp Wikimedia Commons has media related to AS 203 nbsp Spaceflight portal AS 203 Launch Video Archived 2016 07 29 at the Wayback Machine NASA Space Science Data Coordinated Archive Moonport A History of Apollo Launch Facilities and Operations Archived March 18 2011 at the Wayback Machine Chariots for Apollo A History of Manned Lunar Spacecraft Archived October 20 2015 at the Wayback Machine Retrieved from https en wikipedia org w index php title AS 203 amp oldid 1224358182, wikipedia, wiki, book, books, library,
