Editing AS-203 (section)

==Objectives==
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.{{citation needed|date=October 2024}} The lunar missions would use a modified version of the S-IVB-200, the [[S-IVB#Configuration|S-IVB-500]], as the third stage of the [[Saturn V]] launch vehicle. This called for the stage to fire briefly to insert the spacecraft into an Earth parking 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, there would be no [[command and service module]] payload as there was on [[AS-201]] and [[AS-202]], with an aerodynamic [[nose cone]] in the place of the payload. 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.<ref name=":1">{{Cite web |last=Ward |last2=Toole |last3=Ponder |last4=Meadows |last5=Simmons |last6=Lytle |last7=McDonald |last8=Kavanaugh |date=1968-01-13 |title=EVALUATION OF AS-203 LOW GRAVITY ORBITAL EXPERIMENT |url=https://ntrs.nasa.gov/api/citations/19680012073/downloads/19680012073.pdf |url-status=live |archive-url=https://web.archive.org/web/20221018213944/https://ntrs.nasa.gov/api/citations/19680012073/downloads/19680012073.pdf |archive-date=2022-10-18 |access-date=2024-10-07 |website=NASA Technical Reports Server}}</ref> The tank was equipped with 88 sensors and two TV cameras to record the fuel's behavior.<ref name=":2">{{Cite web |title=Apollo 203 (Saturn SA-203) |url=https://space.skyrocket.de/doc_sdat/apollo-203.htm |url-status=live |archive-url=https://web.archive.org/web/20240303183855/https://space.skyrocket.de/doc_sdat/apollo-203.htm |archive-date=2024-03-03 |access-date=2024-10-07 |website=Gunter's Space Page |language=en}}</ref>

This was also the first launch of a Saturn IB from [[Cape Canaveral Air Force Station Space Launch Complex 37|Pad 37B]].<ref name=":2" />