Apollo 6 - 2nd test of the Saturn V launch vehicle

Apollo 6 - 2nd test of the Saturn V launch vehicle
04/04/1968 AD launched

Apollo 6, also known as AS-502, was the third and final uncrewed flight in the US' Apollo Program and the second test of the Saturn V launch vehicle. It qualified the Saturn V to be used on crewed missions, as happened for the first time on Apollo 8 in December 1968.

Apollo 6 was intended to demonstrate the ability of the Saturn V's third stage, the S-IVB, to propel itself and the Apollo spacecraft to lunar distances. Its components began arriving at the Kennedy Space Center in early 1967. Testing proceeded slowly, often delayed by testing of the Saturn V intended for Apollo 4—the inaugural launch of the Saturn V. After that uncrewed mission launched in November 1967, there were fewer delays, but enough so that the flight was postponed from March to April 1968.

The flight plan called for following trans-lunar injection with a direct return abort using the service module's main engine, with a flight time totaling about 10 hours. Instead, a phenomenon known as pogo oscillation damaged some of the Rocketdyne J-2 engines in the second and third stages by rupturing internal fuel lines, causing two second-stage engines to shut down early. The vehicle's onboard guidance system compensated by burning the second and third stages longer, although the resulting parking orbit was more elliptical than planned. The damaged third-stage engine failed to restart for trans-lunar injection. Flight controllers elected to repeat the flight profile of the previous Apollo 4 test, achieving a high orbit and high-speed return. Despite the engine failures, the flight provided NASA with enough confidence to use the Saturn V for crewed launches; a potential third uncrewed flight was cancelled.

Kennedy Space Center, FL

Lattitude: 28.5241° N
Longitude: 80.6508° W
Region: North America

Modern Day United States

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