Apollo Program · Uncrewed test flight

AS-203

Uncrewed test

Launch: 1966-07-05 14:53 UTC
Return: 1966-07-05
Duration: Approximately 4 orbits

Mission summary

AS-203 launched chronologically before AS-202 despite the higher number, owing to vehicle availability. It carried no Apollo spacecraft — the payload was instrumentation to study liquid-hydrogen behavior in the S-IVB upper stage in zero gravity, knowledge later used to plan the Saturn V's trans-lunar injection burn. After four orbits the S-IVB was deliberately over-pressurized to gather structural-limit data, destroying the stage as planned.

Launch vehicle

Saturn IB SA-203

Objectives

Verify behavior of liquid hydrogen propellant in zero gravity in the S-IVB upper stage.
Test the S-IVB venting and propellant-management system in preparation for Saturn V lunar trans-injection burns.
No CSM aboard; the payload was instrumentation only.

Milestones

When	Event
1966-07-05 14:53 UTC	Launched from Cape Kennedy LC-37B with no Apollo spacecraft aboard. https://www.nasa.gov/mission_pages/apollo/missions/as203.html
1966-07-05	S-IVB stage subjected to deliberate over-pressurization on the fourth orbit, destroying the vehicle as planned to gather hardware-limit data. https://history.nasa.gov/SP-4029/Apollo_18-19_Saturn_IB_Launch_Vehicles.htm

Primary sources

Last updated 2026-05-09 15:17 UTC.