Torrence Johnson is one of the world's leading experts on the moons
of the outer solar system. After earning his undergraduate degree in
physics from Washington University in St. Louis, he studied planetary
science at the California Institute of Technology, Pasadena, where he
received his Ph.D. in 1970. Since then, he has worked in many areas of
modern planetary research, including ground-based telescopic
observations, laboratory and theoretical studies and planetary
spacecraft missions. Johnson joined NASA's Jet Propulsion Laboratory in
1973 and has been heavily involved with JPL's planetary exploration
program. On NASA's Voyager mission, he played a major role as a member
of the camera team, planning and analyzing observations of satellites
at Jupiter, Saturn, Uranus and Neptune. In 1977, he was named project
scientist for the highly successful Galileo mission, which achieved its
primary goals in the Jupiter system and continued with extended studies
of Jupiter's moons Europa and Io.