Caption:
Carl Sagan- played a leading role in the American space program since its inception. He was a consultant and adviser to NASA beginning in the 1950s, briefed the Apollo astronauts before their flights to the Moon, and was an experimenter on the Mariner, Viking, Voyager, and Galileo expeditions to the planets. He helped solve the mysteries of the high temperature of Venus, the seasonal changes on Mars, and the reddish haze of Titan.