When Kennedy announced in 1961 that he wanted to take humans to the moon within a decade, Charles M. Duke was skeptical. Almost 11 years later, however, Charles M. Duke was standing on the moon himself. He gave Neil Armstrong the go-ahead for the landing on Apollo 11. Because he contracted rubella, the Apollo 13 crew had to be changed. In 1972, he landed with Apollo 16 and looked down on Earth from the moon himself.