Damon Paul Simonelli died unexpectedly on 1 December 2004 after he collapsed of heart failure at his home near Pasadena, California. Damon led pioneering studies in the scientific exploration of the satellites of the Solar System with spacecraft. He was a longtime member of the AAS's Division for Planetary Sciences community. Only two weeks before his death he attended the 2004 DPS meeting in Louisville where he presented a paper on the surface roughness of Phoebe based on Cassini observations.
Damon was born in the Bronx, New York, on 15 August 1959. His father, Aldo Simonelli (d. 1990), was a clarinetist for the New York City Opera Company, and his mother, Alice Kennard Simonelli, was a secretary. His parents met while they were both students at the Julliard School. Family history has it that Damon's mother was an opera student, but she ruined her voice after singing when she had the flu. By junior high school, Damon had become a master at convincing his mother to wake him up at 3 AM to watch televised moonwalks, and to allow the entire family to view Star Trek episodes at the dinner table. Damon graduated from the Bronx High School of Science in 1976, with a composition on the New York State Regents exam that mentioned the significance of bicentennial toilet bowl lids. In addition to placing great emphasis on humor, the Simonelli family valued education. Damon's younger sister Danelle graduated from Vassar College and has served many years as a U. S. Park Ranger at Liberty Island.
Damon graduated with a BA summa cum laude in physics from Cornell in 1980, where he had begun working with Carl Sagan. Damon had painstakingly gone through all the Viking images to look for any possibility of sentient life on Mars (he didn't find any). Perhaps the arrival of data from the first great explorers of the outer Solar System - Voyagers 1 and 2 - convinced Damon to continue at Cornell with Joe Veverka. While at Cornell, Damon began his pioneering work on the use of quantitative radiative transfer models to understand the physical character of planetary surfaces. He also became interested in post-eclipse brightening on the Galilean satellite Io, a phenomenon that was purported to be due to the condensation of the satellite's tenuous atmosphere during an eclipse by Jupiter. He carefully and skeptically studied this phenomenon, as well as the related problem of night time atmospheric condensation. His thesis was on the microphysical nature and thermal properties of Io's surface. He graduated with a PhD in Astronomy and Space Sciences from Cornell in 1987.
Damon took on a new scientific challenge when he accepted a National Research Council Fellowship at NASA Ames Research Center with Jim Pollack. He worked with Pollack, Ray Reynolds, and Chris McKay on the interior structure of the Pluto/Charon system, and the carbon budget in the outer Solar System. Using new data on the density of Pluto derived from mutual events, Damon led a team that maintained the rockier composition of Pluto implied it formed in a CO-rich outer solar nebula rather than in a circumplanetary nebula. A paper by Simonelli and Reynolds suggested the possibility that Pluto was dense because it had lost its volatiles during an impact event that formed Charon, a suggestion that was later validated by Robin Canup's work. At the time of his death, Damon was a collaborator on the New Horizons Mission to Pluto, due to be launched in early 2006.
Damon returned to Cornell in 1991 to embark on a third scientific career. With Veverka, Peter Thomas, and Paul Helfenstein, he led a team to study the nature of the small, formerly uninteresting bodies of the Solar System, including the inner satellites of Jupiter that were imaged by the Galileo camera. He applied Thomas's "spud" shape model and Helfenstein's Hapke model to derive the shapes, roughness, albedo, and surface texture of a wide range of small bodies, including Io, Phobos, Phoebe, the asteroids Gaspra and Ida, and Europa. Damon also became an expert at planning spacecraft observations and command sequences for Galileo. He was recognized for these efforts with a NASA Superior Performance Award. Damon became known as a patient mentor to undergraduate students, many of whom are coauthors on his papers.
In 2002, Damon left his home turf of Cornell to accept a Senior National Research Council Fellowship at NASA's Jet Propulsion Laboratory with Bonnie J. Buratti. Damon quickly became a key member of the Small Bodies Group at JPL, assuming responsibility for planning the Visual Infrared Mapping Spectrometer (VIMS) Cassini observations of Titan. Although Damon had spent many Friday nights as a Cornell undergraduate conducting open nights at the Campus observatory, his first professional astronomical observing experience was at JPL.
Damon's style in science was always the egoless pursuit of truth. Generous in showing data to competitors, he never took shortcuts when it came to matters of scientific integrity. This good man did not have a single enemy among his colleagues.
Damon was an avid cyclist, amateur actor, and hockey player, continuing his participation in a team even after his move from the great white north to sunny southern California. He had an encyclopedic knowledge of sports, movies, TV, and science fiction, and he owned a world class collection of Star Trek and other science fiction memorabilia, most of which has been distributed to his friends. His science fiction book collection is now part of the Palomar Observatory Library in the Monastery, and his Star Trek collection will be on view at the Altadena Public Library later in 2006.
Although Damon's contributions to science were substantial, and his personal attributes of honesty, selflessness, humor, and intelligence deeply affected his wide circle of friends, his early death left unwritten chapters in both his professional and personal life. The deluge of Cassini data he had intended to work on had just begun to come in, and he will not see the New Horizons launch and encounter. He was devoted to his parents and sister and to the families of his close friends. The Community's tribute to Damon's life will be to continue his work and to keep his spirit of scientific honesty alive. His unique and dry wit and keen scientific insights will be missed.
Damon's survivors include his mother Alice and sister Danelle.