Short Biography for John Spencer (last updated May 2006).

John Spencer is a Staff Scientist at Southwest Research Institute's
Department of Space Studies in Boulder, Colorado.  A native of
England, he obtained a Bachelor's degree in Geology from the
University of Cambridge in 1978, and got his PhD in Planetary Sciences
from the University of Arizona in 1987.  He spent four years in
postdoctoral positions at the University of Hawaii before joining the
staff of Lowell Observatory in Flagstaff, Arizona, in 1991.  He worked
there till he joined Southwest Research Institute in January 2004.

He specializes in studies of the moons of the outer planets,
particularly the four large "Galilean" satellites of Jupiter, using
theoretical models, Earth-based telescopes, close-up spacecraft
observations, and the Hubble Space Telescope.  He was responsible for
temperature mapping of Jupiter's moons with the
Photopolarimeter-Radiometer (PPR) instrument on the Jupiter-orbiting
Galileo spacecraft, and is now assisting in the mapping of
temperatures on Saturn's moons using the Composite Infrared
Spectrometer (CIRS) on the Cassini Saturn orbiter.  He is particularly
interested in the active volcanos and atmosphere of Jupiter's moon Io,
and more recently in the active ice eruptions of Saturn's moon
Enceladus.  He has also published research on Mars, asteroids, Pluto,
and Neptune's moon Triton, and is a science team member on the New
Horizons mission to Pluto and the Kuiper belt.

His observational work has included discovery of several major
volcanic eruptions on Io, the first observations of Io's volcanic
plumes with the Hubble Space Telescope; discovery of sulfur gas in
Io's plumes; co-discovery that Io's atmosphere is highly asymmetrical;
co-discovery of ice volcanic activity on Saturn's moon Enceladus; and
co-discovery of oxygen on Jupiter's moon Ganymede. His theoretical
work has improved our understanding of nitrogen frost on Pluto and
Triton, water frost on Jupiter's moons, and heat radiation from
asteroids.