Astronomer Paul Feldman, a worldwide leading authority on comets who pioneered the field of ultraviolet spectroscopy of comets and professor emeritus in the Department of Physics and Astronomy and Academy Professor at Johns Hopkins University (JHU), died at home on January 26, 2022. He was 82.

As a child, Feldman — a native of Brooklyn — made hand-drawn sky maps and was a member of the junior astronomy club at the Hayden Planetarium in New York. He graduated from Brooklyn Technical High School and earned a bachelor’s degree and Ph.D. (1964), both in physics, from Columbia University. He served as an instructor at Columbia (1964–1965) and as an E. O. Hulburt Fellow at the Naval Research Laboratory (1965–1967), and arrived at JHU in 1967, where he chaired the department from 1996 to 2002. He retired in 2010.

In addition to pioneering contributions to cometary science, Feldman made similar contributions to the fields of planetary and satellite atmospheres and astronomical instrumentation. He was principal investigator of a NASA-supported sounding rocket program and was responsible for more than 50 sounding rocket launches to study Earth’s upper atmosphere, the aurora and the airglow, the atmospheres of comets and planets, the spectra of hot stars, and cosmic background radiation. He is largely responsible for JHU’s reputation as a leader in solar system ultraviolet astrophysics and spectroscopy.

Feldman’s program also developed the UVX experiment that flew on the space shuttle Columbia in January 1986. He was principal investigator for a program of comet studies, including Comet Halley in 1985–1986, using the International Ultraviolet Explorer satellite observatory. He was a co-investigator on the team that developed the Hopkins Ultraviolet Telescope for far-ultraviolet (FUV) astronomy as part of the Astro payload that flew on the space shuttle in December 1990 and again in March 1995, and he was a general observer with the Hubble Space Telescope (HST) and served on the Space Telescope Users Committee from 1992 to 1995. He was also a member of the FUSE science team, a co-investigator on the HST Advanced Camera for Surveys, and a member of the NASA science teams for the Rosetta and Lunar Reconnaissance Orbiter (LRO) ultraviolet spectrometers team and the Europa Clipper Ultraviolet Spectrometer (UVS) team.

Feldman’s work was notable for its great breadth and depth, said Harold (Hal) Weaver, research professor at JHU’s Applied Physics Laboratory and a former student of Feldman’s. Feldman first ventured into the field of cometary science with an ultraviolet sounding rocket experiment to observe the Comet Kohoutek in 1974 and made an inventory of the hydrogen, oxygen, and carbon abundances in the comet’s coma. For the rest of his career, he was what Weaver describes as a “planetary archaeologist,” investigating the origin and evolution of our solar system.

In 1976, during a sounding rocket experiment to observe Comet West, Feldman made the first detection of the carbon monoxide molecule in a comet, recording what is still one of the finest examples of a cometary ultraviolet spectrum ever obtained. The amount of CO in cometary nuclei is key to understanding the formation, conditions, and evolutionary history of comets. Since then, Feldman remained at the forefront of attempts to study cometary CO, using sounding rockets, the International Ultraviolet Explorer satellite observatory, HST, FUSE, and the Rosetta spacecraft.

Feldman was also one of the early leaders in the remote sensing of Earth’s upper atmosphere by rocket-borne spectrometers, and his fundamental research on the radiation from Earth’s upper atmosphere ultimately led to the emergence of the field known as “space weathering.” Feldman also spent time researching the Galilean satellites, serving on the team that discovered molecular oxygen atmospheres on Europa and Ganymede, polar aurorae on Ganymede, and equatorial aurorae on Io. Most recently, he was on the team that discovered fountains of gaseous water emanating from the surface of Europa, which suggests there might be life below that moon’s thick ice shell. His work with the JHU Ultraviolet Telescope delivered spectacular spectra of Jupiter’s dayglow that are the definitive data for unraveling the fundamental processes that create Jupiter’s ultraviolet luminosity, and he led that telescope’s investigations of Mars and Venus, with similarly significant results.

Feldman was an Alfred P. Sloan Foundation fellow (1969–1974) and a Fellow of the American Physical Society, and was a member of the American Astronomical Society, American Geophysical Union, and International Astronomical Union. He served as associate editor of the Journal of Geophysical Research: Space Physics and was a member of the editorial board of Icarus and of the Committee on Planetary and Lunar Exploration of the National Academy of Sciences’ Space Science Board from 1985 to 1988. In addition to his scientific prowess and lasting impact on his fields, Feldman is remembered as a dedicated colleague and mentor who supervised dozens of Ph.D. theses, significantly shaping the next generation of researchers.

Feldman’s family has established The Paul D. Feldman Fellowship in Far Ultraviolet Spectroscopy from Space. Gifts in his memory can be made to the fellowship fund at https://secure.jhu.edu/form/krieger.

— Text courtesy of Johns Hopkins University