Bill Smyth passed away on September 30, 2011, as a result of complications from a respiratory infection after a 6-week battle waged in Wake Forest hospital in Salem, North Carolina. His pioneering work on planetary exospheres and atmospheres contributed significantly to the understanding of the smaller bodies in the solar system and their interactions with the surrounding charged particle and electric and magnetic fields environment.
Bill was born on September 5, 1941, in Arlington, VA, to William Henry and Hazel Tysinger Smyth, the middle of three children that included an older sister, Hazel, who died in 2000 and a younger brother, Robert, who died in 2009. In 1949, the family moved back to Hazel’s home town, Denton, NC, where, while attending high school, Bill developed a strong interest in mathematics and the physical sciences. This led Bill to obtain an undergraduate degree from North Carolina State University in 1963 with high honors and then enter the graduate school at Harvard University in the department of Applied Physics, where he completed a thesis under Max Krook on the kinetic theory of gases interacting with radiation. After graduating, Bill remained at Harvard, first as a post-doc under Michael McElroy and then as a research fellow until 1978, where he began to apply his expertise in the kinetic theory of gases interacting with radiation on satellites of the outer planets and their extended neutral atmospheres. At that time he began his work on Io’s neutral clouds, which he continued throughout his entire career.
Bill became an early member of the then-recently-founded research firm Atmospheric and Environmental Research (AER), Inc., in 1977 and spent the remainder of his career there, much of it as head of the planetary sciences group. Upon joining AER, Bill continued the development of the neutral cloud model that he used to conduct his seminal work elucidating the neutral clouds and corona of Io. This new state-of-the art model was primarily developed between 1980 and 1988; in addition to that for Io, versions for Titan and comet atmospheres were also created. In the process of developing this model, Bill realized the importance of the interaction of the neutral gases with the ambient plasma. As a result, Bill also turned his attention to the Io plasma torus, leading to the development of a state-of-the-art model for the Io plasma torus that was subsequently incorporated into the neutral-cloud model. Between 1990 and 2000, Bill continued to advance the modeling of Io’s corona and neutral clouds and also developed versions of the model for Mercury and the Moon. Because of his leading work on Io’s corona and neutral clouds, Bill was awarded an IDS position on the Galileo mission in 1997. During this time Bill also developed a model for the hydrogen from Titan that explained the asymmetry in the Saturnian hydrogen-cloud distribution.
After 1995, Bill returned to kinetic theory and began pioneering atmospheric models that consistently described the atmosphere through all levels of collisionality. This soon led to the construction of a novel, spherically symmetric hybrid-fluid kinetic model for an Io-like atmosphere whose spatial domain stretched from the collisional surface through the quasi-collisional middle atmosphere and well out into the plasma torus, thus linking the planet surface, atmosphere, and magnetosphere. In 1998 Bill was diagnosed with a non-Hodgkins lymphoma that was successfully treated with intense radiation and chemotherapy. Bill returned to full-time research the year after, and in 2006 published a state-of-the-art axisymmetric kinetic model for Europa’s atmosphere. In 2007 he was diagnosed with MDS, as a complication of the previous lymphoma treatments, which was treated with a whole-body stem-cell transplant. While this successfully treated the MDS, Bill never fully recovered from the procedure and was significantly physically impaired thereafter from various complications. Nevertheless, he remained productive, continued to work through the difficulties, and managed to create a new version of the Io plasma-torus model that is the best currently available. During this time he also extended Chamberlain’s single body classical treatise on planetary exospheres to the two-body case and continued to advance the modeling of satellite atmospheres with a novel coupled electrodynamic/kinetic model for Io’s atmosphere. Bill was a leading expert on planetary exospheres and atmospheres and probably the pre-eminent authority on Io’s exosphere, neutral clouds, and the Io plasma torus.
Throughout his career, Bill demonstrated an uncommon honesty in research, attention to detail, and a penetrating insight.
Bill was also a devout Christian who was deeply involved in his local church. A favorite scripture quote of his was “The heavens declare the glory of God; the skies proclaim the work of His hands. Day after day they pour forth speech; night after night they display knowledge. There is no speech or language where their voice is not heard. Their voice goes out into all the earth, their words to the ends of the world.” (Psalm 19:1-4)
He is survived by his wife, Iris, daughter, Lisa, and sons, Peter and Jon. Bill will be greatly missed.