AS-203

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.

Preparation

In the spring of 1966 it was decided to launch AS-203 before AS-202 as the CSM that was to be flown on 202 was delayed. The S-IVB stage arrived at the Cape on 6 April, 1966 and the S-IB first stage arrived six days later and the Instrument Unit came two days after that.

From the 19 April technicians began to erect the booster at Pad 37B. Once again the testing regime ran into problems that had plagued AS-201. The problem was due to cracked solder joints in the printed-circuit boards, causing over 8000 to be replaced.

June 1966 saw three Saturn rockets set up on various pads across the Cape. At Pad 39A was a full size mockup of Saturn V, at 34 was AS-202 and 37B was AS-203.

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 the fuel behaved just as predicted. It was observed over four orbits and then the stage was pressurised to see how much pressure it could stand. In the end this test exceeded the structural abilities of the stage and it fragmented.

Apart from stage being lost, the mission was classed as a success and achieved all 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.

External links

* [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680012073_1968012073.pdf Evaluation of AS-203 Low Gravity Orbital Experiment - Jan 1967 - NASA (PDF format)]
*http://nssdc.gsfc.nasa.gov/database/MasterCatalog?sc=1966-059A
* [http://www.hq.nasa.gov/office/pao/History/SP-4204/cover.html Moonport: A History of Apollo Launch Facilities and Operations ]
* [http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html Chariots for Apollo: A History of Manned Lunar Spacecraft ]