Carl Sagan was the David Duncan 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 missions to the planets and briefed the Apollo astronauts before their flights to the Moon. He helped solve many mysteries in planetary science from the high temperature of Venus to the seasonal changes on Mars. For his unique contributions, he was awarded the NASA Medals for Exceptional Scientific Achievment and for Distinguished Public Service (twice), as well as the Tsiolkovsky Medal of the Soviet Cosmonautics Federation, the John F. Kennedy Award of the American Astronautical Society and the Arthur C. Clarke Award for Space Education.
