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James B. Pollack, world-renowned expert in the study of planetary atmospheres and particulates using nongrey radiative transfer techniques, died June 13 from a rare form of cancer. His work led to many advances in our understanding of the Solar System, including evolutionary climate change on all the terrestrial planets and detailed models of the early evolution of the giant gas planets.
Dr. Pollack participated in every major NASA flight mission since Apollo. He made fundamental contributions to the design, development, and implementation of the Mariner Mars series, Pioneer Venus, Viking, Voyager, Galileo, and Cassini, and was a key player in Mars Observer and CRAF. He was a member of the imaging teams of the Mariner 9 orbiter of Mars, the Viking Lander on Mars, and the Voyager spacecraft for the Saturn, Uranus, and Neptune encounters.
His discoveries include the first real evidence that the clouds of Venus are composed of sulfuric acid, and the resolution of a major paradox concerning Saturn's rings. He first conceived that nearly lossless scattering by wavelength-sized particles of waterŠice could explain the low microwave emissivity and high radar reflectivity of Saturn's rings. Dr. Pollack also led a team in modeling the luminosity evolution of giant gas planets during their primordial contraction stages. These models were applied to explain the density gradient in the Galilean satellites as a natural outcome of their location relative to luminous proto-Jupiter. Until his death, he was a senior space research scientist at the NASA Ames Research Center in California.
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