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James L. Elliot, Professor of Planetary Astronomy and Physics at MIT, has passed away Wednesday night March 2, 2011. Jim was one of the pioneers in using stellar occultations to probe planetary atmospheres and the physical properties of small bodies in the outer solar system and beyond. Among his accomplishments are the discoveries of the ring system of Uranus and the atmosphere of Pluto. He received his undergraduate degree from MIT in 1965 and his Ph.D. from Harvard in 1972. Before returning to MIT in 1978, he was a postdoc and faculty member in the Astronomy Department of Cornell University. Jim was a wonderful mentor and teacher, and was especially supportive of women in astronomy. We will miss him deeply.

Donald Mount Hunten passed away on the 14th of December, 2010.

He was born in Montreal, before his family moved to London, Ontario where Don attended the Western Ontario University In 1946 he enrolled in the Ph.D. program at McGill University, back in Montreal, where he obtained his PhD in 1950. He later became assistant professor at the University of Saskatchewan. After Joe Chamberlain moved to Kitt Peak National Observatory in Tucson to form a space research group, he invited Don to join it and so Don moved to Tucson. In 1974 he became professor at the Lunar and Planetary Lab. In 1982 he was inducted into the National Academy of Sciences and he eventually became a Regents Professor at LPL, UA.

Borrowing from a citation by T. Owen at the 1998 John Adam Fleming Medal of the American Geophysical Union honoring Don:

Donald M. Hunten is a model for all of us engaged in the study of planetary atmospheres. He is first of all a superb scientist, one of the finest aeronomers our planet has produced. He is that rare combination of instrumentalist, observer, theorist, and responsible representative of his field that makes a “compleat” scientist. Don’s contributions are evident everywhere in the record of terrestrial and planetary aeronomy. In the 1950s, he was preeminent among those who developed the ground-based instruments that obtained the spectra required for an understanding of the excitation of Earth’s airglow and aurora, and he also developed the theories that explained the data. In the early 1960s, he contributed to the deflation of the Martian atmosphere by demonstrating the weak points in earlier attempts to derive the red planet’s surface pressure. Don was the godfather of the Pioneer Venus mission and a key scientist in its highly successful implementation and the analysis of the results.

One of his greatest achievements was the development of the theory of diffusion-limited escape and the subsequent analysis of escape of hydrogen from the planets Turning to the outer solar system, Don developed a model for the atmosphere of Titan prior to the Voyager 1 encounter in 1980 that was so good it became the standard after the data came in confirming it. With his extraordinary intuition and insight, he had correctly surmised that Titan must have a massive, molecular nitrogen atmosphere, well before there was any detection of N or N2 on this intriguing satellite. In the following decade, Don used his excellent grasp of physics together with his extensive experience in deep space missions to play a critical role in the design of the Cassini-Huygens mission, now safely on its way to Saturn and
Titan.

Don Hunten also worked on the analysis of data from the Galileo Probe into Jupiter’s atmosphere and investigated the tenuous, gaseous envelopes around Mercury and the Moon. He has been an inspiration and a mentor for many of the currently confirmed planetologists.

Materials from the Donald Hunten memorial session at the 2011 DPS conference:

1. Hunten Session Package
2. Hunten talk – Belton
3. Hunten talk – Yelle
4. Hunten talk – dePater
5. Hunten talk – Lunine part 1
6. Hunten talk – Lunine part 2
7. Hunten talk – Schneider

Brian Geoffrey Marsden was born on August 5, 1937, in Cambridge, England. He was an undergraduate at New College, University of Oxford. By the time he received his undergraduate degree, in mathematics, he had already developed somewhat of an international reputation for the computation of orbits of comets, including new discoveries, and spent part of his first two undergraduate summer vacations working at the British Nautical Almanac Office.

After Oxford, in 1959, he worked at the Yale University Observatory, where he started computing the orbits of comets. Recalling his earlier interest in Jupiter’s moons, he completed the requirements for his Ph.D. degree with a thesis on “The Motions of the Galilean Satellites of Jupiter”. At the invitation of director Fred Whipple, he joined the staff of the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts in 1965 where he developed a way to incorporate forces over and above those of gravitation directly into the equations that governed the motion of a comet. It is noteworthy that the procedure devised and developed by Marsden is still widely used to compute the non-gravitational effects of comets, with relatively little further modification by other astronomers.

Marsden succeeded Dr. Owen Gingerich as the CBAT director in 1968 and in 1978 the IAU asked him to also take over the direction of the MPC.

Marsden was also interested in the “transneptunian objects”. More specifically, he was the first to suggest, correctly, that three further transneptunian objects discovered in 1993 were exactly like Pluto in the sense that they all orbit the Sun twice while Neptune orbits it thrice. This particular recognition set him firmly on the quest to “demote” Pluto. Success required the discovery of transneptunian objects more comparable to Pluto in size, something that finally happened in 2005 with the discovery of the object that came to be known as Eris. At its triennial meeting in 2006 in Prague, the IAU voted to designate these objects, together with two further transneptunian objects now known as Makemake and Haumea, as well as the largest asteroid, Ceres, members of a new class of “dwarf planet”. It was also at the IAU meeting in Prague that Marsden stepped down as MPC director, and he was quite entertained by the thought that both he and Pluto had been retired on the same day.

Marsden served as an associate director of the Harvard-Smithsonian Center for Astrophysics for more than 15 years; he was chair of the Division of Dynamical Astronomy of the American Astronomical Society during 1976-1978 and president of the IAU commissions that oversaw the operation of the minor Planet Center (1976-1979) and the Central Bureau for Astronomical Telegrams (2000-2003). He continued to serve subsequently on the two solar-system nomenclature committees of the IAU, being the perennial secretary of the one that decides on names for asteroids. He also continued to publish a “Catalogue of Cometary Orbits”, the first of these having appeared in 1972 and its successors roughly at intervals of two years.

B. Marsden passed away on 18 November and will be sorely missed by our community.

Dr. Ralph Belknap Baldwin died peacefully on October 23, 2010, at age 98.
Born on June 6, 1912, he graduated from the University of Michigan with a B.S. in 1934, an M.S. in 1935, and a Ph.D. in Astronomy (Physics) in 1937. He taught astronomy at the Universities of Michigan, Pennsylvania, and Northwestern. Baldwin received three honorary degrees, an LLD from Michigan in 1975, an ScD from Grand Valley State University in 1989, and an ScD from Aquinas College in 1999. During World War II he was a Senior Physicist at the Applied Physics Laboratory of Johns Hopkins University, helping develop the radio proximity fuze. After the war he returned to Grand Rapids and joined Oliver Machinery Company where he became its President in 1970. Baldwin’s most important work was in astronomy. His studies proved that the craters on the Moon were produced by the impacts of large and small asteroid-like bodies rather than volcanic in origin. Baldwin’s early work culminated in his book, “The Face of the Moon” (1949), which may properly be considered the generating force behind modern research in both terrestrial impact craters and lunar surface features. He followed up his original work with a second book, “The Measure of the Moon” in 1965. Baldwin was a Fellow in the Meteoritical Society, the American Geophysical Union, the American Association for the Advancement of Science, and the American Academy of Arts and Sciences. The Royal Astronomical Society of Canada made him an Honorary Member.

Thomas J. Ahrens, one of the leading figures in mineral physics, geophysics, and planetary sciences during the Twentieth Century and a member of the Seismological Laboratory, passed away on November 24, 2010 at the age of 74.

Ahrens spent more than forty years at Caltech and was the Fletcher Jones Professor of Geophysics, Emeritus when he passed away. His vast research accomplishments and impact touched on the origin, differentiation and evolution of the Earth and planets. An experimentalist at heart, he was widely known for starting and leading the Lindhurst Laboratory of Experimental Geophysics. Through the more than thirty graduate students and fifteen post docs and visiting associates he mentored, his impact on science will be felt for many years to come.

Born in Germany, Ahrens received his BS from the Massachusetts Institute of Technology in 1957, his MS from Caltech in 1958, and his PhD from Rensselaer Polytechnic Institute in 1962. He was a geophysicist with the Pan American Petroleum Corporation from 1958 to 1959, worked as a second lieutenant for the U.S. Army in the Ballistics Research Laboratory from
1959 to 1960, and was the head of the geophysics section in the Poulter Laboratory of the Stanford Research Institute from 1962 to 1967. He became professor of geophysics in 1976 and was the W. M. Keck Foundation Professor of Earth Sciences from 1996 to 2001. In 2004, he was named the Fletcher Jones Professor of Geophysics and became Jones Professor, Emeritus, in 2005. He made the link between the Earth’s seismic structure, its composition, and its physical properties. Exploring the pressures and temperatures opened by the shock wave facility, he and his associates determined the first experimentally based equations of the state of the deep mantle and core and made the first experimentally based estimates of the temperature of the core.

The French astronomer and aeronaut Audouin Dollfus passed away October 1, 2010 in Versailles, France, at the age of 85. Born November 12, 1924 in Paris and son of an aeronaut, he built his first refracting telescope at the age of 14. Graduated in Mathematical Sciences and Physics, he started his career at the Observatory of Paris-Meudon as a student of astronomer Bernard Lyot. At a time when astronomy was focusing on deep sky, Dollfus turned to the study of the Solar System, and became a worldwide expert on the subject. He created the Laboratory of Solar System Physics at Meudon, studying all planets, with special interest in Mars, Venus, Mercury, Saturn and Jupiter. He also contributed to the study of the Sun through the development of a coronagraph that was used by many spacecraft missions. Dollfus led astronomical campaigns both at the Observatory of Meudon and the Pic-du-Midi Observatory. He discovered Janus, 10th satellite of Saturn in 1966, and asteroïd 2451 bears his name. The breadth and reach of his research and his numerous (330) scientific publications allowed him to contribute to many international committees.

His analysis of the Lunar dust using polarimetry allowed him to deduce the basaltic nature of the Lunar soil (1955). As a result, NASA invited him to collaborate to the study of the Apollo 11 landing site and to provide expertise for the design of the astronauts Moonboots. He contributed to the analysis of the Lunar samples returned by the Apollo program and to the studies of the Martian soil in preparation to the Viking mission, which landed in 1976 on Mars. In addition to Apollo, he collaborated with NASA on the Ranger and the Venus Mariner programs, and to the Soviet Mars-5 mission in 1973.

Expert in planetary mapping, he created the International Center for Planetary Photography at Meudon, from which stemmed many maps and nomenclatures, domains that were highly innovating to the time.

Audouin Dollfus was above all a pioneer of space exploration through his practice of astronomy using balloons. Bringing together his two passions of astronomy and balloons, he designed prototypes that allowed him to take a telescope up to 6,000 m (19,700 ft) in the air in a simple nacelle. His most spectacular and famous flight remains that of April 24, 1959, when taking off from Villacoublay near Paris, he reached 14,000 m (45,920 ft), still the French record today, opening the path to the study of astronomy from space. The data he collected during that flight allowed him to infer the existence of water on Mars.

Talented mongolfiere and balloon pilot, he held several world records for flight duration, distance, and altitude in free ballooning. Historian of sciences, historian in aeronautics, and member of the Aero-Club de France, Dollfus was also dedicated to passing on his passion for astronomy and never refused an opportunity to share his enthusiasm through lectures, debates, and talks to astronomy and aeroclubs. He mentored students in astronomy and planetary sciences. Many of them are today directly involved in planetary and space exploration. He was the recipient of many prizes and recognitions and has also written several books.

N. Cabrol and his colleagues at Meudon Observatory

The DPS joins the astronomical community in mourning the untimely death of John Huchra, distinguished astronomer and Past President of the AAS, on October 8. John was a friend of the DPS in our time of financial crisis, when he was serving as the AAS President. He will be sorely missed.

From the AAS Informational Email 2010-8:
John was one of those unique astronomers with friends and interests across the whole discipline. He stayed vigorous and active in our field even after suffering a heart attack a few years ago. John was passionate about astronomy and life, full of energy and ideas. He served the Society phenomenally well in his two years as president (and year as president-elect and in his current term as past president). During the same time he served the Society, he served our discipline by working actively on the Decadal Survey Committee. He was always willing to say yes to committee service and always offered sage advice. His research and his AAS and Decadal Survey visions are a legacy for us all. It was an honor and a privilege to work and laugh with him, and we will very much miss his presence at the table of past leaders of our Society. We cannot yet grasp this devastating news, except to know there’s now a great void and a shared profound sadness.