The first four manned missions in the Apollo series. The flights developed and tested the hardware, systems and techniques essential for a successful moon landing.

Apollo 7 - shakedown cruise of new Apollo spacecraft. Apollo 8 - First flight to venture beyond low-earth orbit and travel to the moon over Christmas 1968. Apollo 9 - First test flight (in earth orbit) of full spacecraft combination, CSM and LM. Apollo 10 - Dress rehearsal for the moon landing test of full spacecraft combination with LM descending to within 9 miles of the lunar surface.