It is with profound sadness that we announce the untimely death on 22 February 2002, of our dear friend and colleague, Dr. Thomas J. Sodroski, the son of Walter and Catherine Sodroski. At the time of his death Tom was working with his colleague Dr. Nils Odegard, at NASA Goddard Space Flight Center, developing models for the origin of the diffuse Galactic gamma ray emission from the Milky Way, and providing scientific support for the archivingl and dissemination of astronomical data at the National Space Science Data Center (NSSDC).
Tom was born on 10 September 1958 in the coal-mining town of Summit Hill, Pennsylvania. The setting of the small town provided an ideal backdrop for Tom's youthful imagination. The youngest of three boys, Tom showed an early affinity for astronomy, spending many clear nights in the backyard with telescopes. Tom's interest in astronomy led him to rocketry, starting initially with crude space capsules, which later evolved with the help of local machinists, teachers and craftsman into quite sophisticated solid- and liquid-fuel rockets.
After his graduation from Marian High School in Hometown, Pennsylvania, Tom obtained his undergraduate degree from Lehigh University. He spent a post-graduate year at the University of Pennsylvania, where he met Biya—his future wife. Tom then moved to College Park where he pursued his life long passion in the Astronomy Department of the University of Maryland. He received his PhD degree in 1988 under the supervision of the late Professor Frank Kerr who pioneered the largest atomic hydrogen survey of the Milky Way, and Dr. Michael G. Hauser, then a member of the Infrared Astronomical Satellite (IRAS) Science Team. For his thesis, Tom pioneered the application of numerical inversion techniques to radio and infrared surveys of our Galaxy in order to infer the three dimensional structure of its interstellar medium (ISM). Tom developed a model for the large-scale distribution of interstellar dust in the Galaxy, and its association with the molecular, atomic, and ionized phases of the ISM. During the period of his dissertation Tom demonstrated outstanding abilities as a scientist especially in his analysis and interpretation of observational data. For his thesis he wrote the first major and still the best papers on the distribution of interstellar gas in the ISM using the IRAS data.
Following his PhD, Tom was awarded a National Research Council (NRC) Resident Research Associateship at the Infrared Astrophysics Branch at NASA Goddard Space Flight Center. At that time, a major issue in galactic studies was the amount of molecular hydrogen present in the ISM. Its abundance is inferred from the presence of another molecule, CO, and depends on the factor used to convert from CO to molecular H abundance. Astronomers usually adopted a single numerical value for the conversion ratio throughout the Galaxy. However, Tom's studies on this topic showed that this ratio varies in the Galaxy. He derived its numerical value as a function of Galactocentric radius—quite a revolutionary discovery at that time.
After completing his NRC Fellowship, Tom joined the team of scientists entrusted with the analysis of data obtained from the Diffuse Infrared Background Experiment (DIRBE) instrument on board the Cosmic Background Explorer (COBE) satellite. During this period, Tom was assisting in the search for the diffuse infrared background, and was a lead investigator on some of the important scientific publications made possible by the DIRBE data. In 1997, using this data, he presented a three-dimensional model for the infrared emission from the Milky Way, depicting the contribution of each of the different gas phases of the ISM to the large-scale emission from our galaxy. His work on the subject is widely cited, and to date unsurpassed in scope and quality.
During his graduate studies Tom acquired (out of necessity) an intimate knowledge of the inner workings of car engines, which he used to help fellow students repair and maintain their cars. He also loved to scout the antique markets for bargains, and restored antique furniture as a hobby. Tom was an avid lover of the outdoors, constantly exploring the web of biking and hiking trails in the area around Washington DC, exploring Civil war battle sites, spelunking, and sailing the waters of the Chesapeake Bay.
Tom had a healthy sense of humor and a circle of close friends who could always rely on his assistance. He will be greatly missed by all his friends and colleagues. Tom was laid to rest on March 1, 2002 in his home town in Summit Hill. He is survived by his mother, brothers Joseph and Tony, and Biya and son Jake.