Torrence V. Johnson is a specialist on icy satellites in the solar system. He has written over 130 publications for scientific journals. He received a Ph.D. in planetary science from the California Institute of Technology and is now the Chief Scientist for Solar System Exploration at the Jet Propulsion Laboratory. He was the Project Scientist for the Galileo mission and is currently an investigator on the Cassini mission. He is the recipient of two NASA Exceptional Scientific Achievement Medals and the NASA Outstanding Leadership Medal and has an honorary doctorate from the University of Padua, where Galileo made his first observations of the solar system.