Before we walked on the moon, he flew two other space missions. Cernan had previously served as the lunar module pilot on Apollo 10 and was a pilot on the Gemini IX mission. Cernan became the second American to walk in space on the Gemini IX mission in 1966 and flew within 8 miles of the Moon's surface on Apollo 10, just two months before Apollo 11 landed and walked on the Moon. What A Great Life!