During the 1950s, Tom Gehrels pioneered the inaugural photometric system used for studying asteroids, a fundamental shift in how planetary scientists catalogued the solar system. Over a career spanning five decades at the University of Arizona, he transitioned from high-stakes intelligence operations as a young man to a prolific observational career that identified thousands of new celestial objects.
Military Service and Academic Foundations
Born in Haarlemmermeer in 1925, Gehrels spent his early adulthood involved in clandestine operations in Europe and the Far East between 1944 and 1948. Following this period, he pursued formal scientific training, earning a degree in physics and astronomy from Leiden University in 1951. He moved to the United States to complete his doctoral studies at the University of Chicago, graduating in 1956 under the supervision of Gerard P. Kuiper.
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In 1960, Gehrels joined the University of Arizona, where he remained for the duration of his professional life. He became known for his extensive survey work using the 48-inch Schmidt telescope at the Palomar Observatory. By shipping observational plates to colleagues Cornelis Johannes van Houten and Ingrid van Houten-Groeneveld at Leiden Observatory, he facilitated the discovery of over 4,000 asteroids, including significant numbers of Apollo, Amor, and Trojan bodies. Beyond this survey, he was also responsible for identifying a number of individual comets.
Deep Space Instrumentation and Publishing
Gehrels served as the Principal Investigator for the Imaging Photopolarimeter experiment on the Pioneer 10 and 11 missions, which performed the first flybys of Jupiter and Saturn during the 1970s. He later founded the Spacewatch program in 1980 to advance electronic surveying of near-Earth objects. Beyond his field research, he established the Space Science Series for the University of Arizona Press, acting as the general editor for the first 30 volumes.
Professional Recognition and Later Research
In his later years, his academic focus shifted toward cosmology and the evolution of the universe, themes he integrated into his undergraduate courses in Tucson and his lectures at the Physical Research Laboratory in Ahmedabad, India. In 2007, he received the Harold Masursky Award for his contributions to planetary science. He died in 2011 in Tucson, leaving behind a legacy recognized by the naming of minor planet 1777 Gehrels.
Fast facts
- Born: 21 February 1925, Haarlemmermeer, Netherlands
- Died: 11 July 2011, Tucson, Arizona
- Citizenship: United States; Kingdom of the Netherlands
- Ph.D.: University of Chicago, 1956
- Career tenure: University of Arizona, 1961–2011
- Major award: Masursky Award, 2007
- Notable contribution: Principal Investigator for Spacewatch
Questions readers ask
What was the Spacewatch program?
Initiated by Gehrels in 1980, it was a project dedicated to the electronic surveying of asteroids and comets, including those identified as near-Earth objects.
What was Gehrels' role during the Pioneer missions?
He served as the Principal Investigator for the Imaging Photopolarimeter experiment during the first flybys of Jupiter and Saturn.
Achievements
- Notable work: discoverer of asteroids
- Held posts at University of Arizona
- Educated at Leiden University and University of Chicago
- Fields of research: astronomy and student
