Carl Sagan was Professor of Astronomy and Space Sciences and Director of the Laboratory for Planetary Studies at Cornell University. He played a leading role in the Mariner, Viking, and Voyager spacecraft expeditions to the planets, for which he received the NASA medals for Exceptional Scientific Achievement. Dr. Sagan received the Pulitzer Prize and the highest awards of both the National Academy of Sciences and the National Science Foundation, and many other awards, for his contributions to science, literature, education, and the preservation of the environment.