John Spencer, Southwest Research Institute
The New Horizons spacecraft flew past Pluto on July 14th last year, revolutionizing our understanding of this remarkable distant dwarf planet and its moons. The flyby was the culmination of over two decades of effort, including a journey from Earth that lasted more than nine years. Pluto has emerged as a world of spectacular variety. It has some of the brightest and darkest surfaces in the solar system, including exotic ices such as frozen nitrogen and carbon monoxide; landscapes that are ancient and landscapes that are still being renewed; and a flowing icecap that sits, bizarrely, astride its equator. Its tenuous hazy atmosphere extends so high above Pluto's surface that it leaks constantly into space. Pluto's family of moons have surprises of their own, including world-encircling fractures and a dark red polar cap on the giant moon Charon, and four small moons with strange shapes and mysterious orbits and rotations. Though the New Horizons spacecraft has now left Pluto far behind, its mission continues deeper into the Kuiper Belt, the vast region beyond Neptune occupied by hundreds of thousands of small worlds left over from the formation of the solar system. If an extended mission is approved by NASA, the spacecraft plans to visit one of these worlds in early 2019.
John Spencer is an Institute Scientist at the Southwest Research Institute in Boulder, Colorado, and a member of the New Horizons science team. A native of England, he obtained his PhD in Planetary Sciences from the University of Arizona in 1987, and has since worked at the University of Hawaii and at Lowell Observatory in Flagstaff, Arizona (where Pluto was discovered) before joining Southwest Research Institute in 2004.
John studies the moons and other small bodies of the outer solar system using ground-based telescopes, the Hubble Space Telescope, and close-up spacecraft observations. He was a science team member on the Galileo Jupiter orbiter and continues to work on the science team of the Cassini Saturn orbiter.
Among other work, he was involved in the discovery of current activity on Saturn's moon Enceladus, solving the mystery of the black-and-white appearance of Saturn's moon Iapetus, and the discovery of oxygen on the surfaces of Jupiter's icy moons.