'Neil' Gehrels

PUBLISHED: 4 APRIL 2017 | VOLUME: 1 | ARTICLE NUMBER: 0109 obituary Cornelis A. ‘Neil’ Gehrels Neil Gehrels passed away on 6 February 2017. A pioneer of observational high-energy astrophysics, he was an exceptional leader, scholar, colleague and friend.

he scientific community suffered Investigator of the Swift Gamma-Ray a tremendous blow with the death Burst Mission. Neil led Swift from its Tof Neil Gehrels, who passed away inception, through development and, on 6 February 2017 after a battle with more than twelve years after its launch in pancreatic cancer. Through his research 2004, to Swift’s position as one of NASA’s and leadership, he was a driving force in most scientifically productive missions. gamma-ray astrophysics up to his death but Swift was initially dedicated to gamma-ray also worked in the diverse fields of planetary burst studies, and it made many important sciences, galaxy evolution and gravitational discoveries, including the first identification wave astronomy. of afterglows of short-duration events. Niel grew up in a scientific family. His The mission broadened its observational father, Tom Gehrels, himself an eminent scope over time, becoming a powerful tool scientist, was instrumental in propelling the for studies of a wide range of transient University of Arizona into a powerhouse phenomena, from supernovae to neutron in astronomy and planetary sciences. In stars and black holes. Neil oversaw this spite of this, Neil did not initially imagine transformation, always enthusiastic and a career in science, his early passion being excited about new scientific directions. For music. As an undergraduate music student his role on Swift he was awarded (with the at the University of Arizona he aimed to Swift team) the Bruno Rossi Prize of the hone his skills playing clarinet, guitar and American Astronomical Society, and the piano — his goal was to become a classical Henry Draper Medal from the National music composer. Later he added physics COUNCIL SCOTT Academy of Sciences. Very shortly before as a double major, and became enamoured Cornelis A. ‘Neil’ Gehrels (1952–2017) his death he was awarded the prestigious of research. Neil took this newfound love Dan David Prize for his role in the up-and- to Caltech, where he pursued his PhD in coming field of transient astrophysics. Caltech’s Space Radiation Laboratory with centre of the Milky Way at energies in the In the last decade of his career Neil the noted physicists Rochus ‘Robbie’ Vogt range 100 keV to 10 MeV. This experiment began to devote his talents outside of and Ed Stone. Neil’s first project was to detected broadened radioactive decay high-energy astrophysics. As a result of calibrate a cosmic-ray instrument on lines of 56Co from the famous SN1987A early involvement with the Joint Dark Voyager. In 1979, when Voyager flew past supernova, providing the first evidence Energy Mission he became the project Jupiter, Neil analysed the data from this that the material ejected by the demise scientist for the Wide Field Infrared Survey instrument, making the surprise discovery of this massive star was strongly mixed Telescope, NASA’s next flagship to follow of oxygen and sulfur in the planet’s and asymmetric — clues central to the James Webb Space Telescope. He was magnetosphere. Gehrels and Stone deduced understanding the explosion mechanism. also a core member of the LIGO Scientific that the particles were expelled by volcanos Neil then moved on to leadership Collaboration. For his contributions to on Jupiter’s moon Io, a discovery that was positions on a series of gamma-ray space science, he was inducted into the American a highlight of the Voyager mission, and missions. He was the project scientist of Academy of Arts and Sciences and the remains one of Neil’s most-cited results. the Compton Gamma Ray Observatory National Academy of Sciences. It was at Caltech where Neil met his life (CGRO), the first mission in the line of four Although his time was cut short, Neil partner, Ellen Williams. Ellen and Neil (both NASA Great Observatories that established lived a full life. He was an incredibly given Caltech’s distinguished alumni award that gamma-ray bursts — bright flashes of productive scientist, with over 750 last year) were married on campus in 1980, energetic radiation lasting a few seconds — publications. Outside the office, Neil was and moved to Maryland two years later. result from two distinct populations. By an avid mountaineer — almost every trip Ellen joined the University of Maryland the end of CGRO’s mission in 2000, the to a scientific conference was combined as a professor of physics, and Neil went to census of cosmic gamma-ray sources had with the ascent of some high peak. In the Goddard Space Flight Center, where he gone from a few to many thousands. Neil 2006 and again in 2015 Neil climbed the spent the rest of his career. described this time of discovery as one of Nose route on El Capitan in Yosemite in At Goddard Neil turned his attention the best in his professional life. Neil went six-day solo ascents. Neil devoted significant to gamma-ray astrophysics, a field which, on to be US Mission Scientist of the ESA’s time to scientific advisory roles, where his with crude instruments and just a handful INTEGRAL mission, and Deputy Project thoughtful, deliberative style was highly of known cosmic sources, was in its Scientist for NASA’s Fermi Gamma-ray valued. Together with his family — Ellen infancy. Neil led a team that developed a Space Telescope. and their two children, Thomas and balloon-borne gamma-ray spectrometer Neil’s crowning achievement in high- Emily — he volunteered in disadvantaged that made detailed observations of the energy astrophysics was his role as Principal Maryland communities, and in 2005 Neil

NATURE ASTRONOMY 1, 0109 (2017) | DOI: 10.1038/s41550-017-0109 | www.nature.com/natureastronomy 1 ©2017 Mac millan Publishers Li mited, part of Spri nger Nature. All ri ghts reserved. obituary helped establish an internship program for enthusiasm for all science, and in particular the community are still reeling from the impoverished local high school students to he would go out of his way to find out what news of his passing. But we celebrate this work in his labs. young researchers were up to — frequenting life lived fully, and Neil’s legacy will live on Neil was disarmingly friendly, the poster sessions at conferences and with each new discovery from the missions unassuming, and one of the most genuine getting to know the students who were using he helped to create. ❒ people I have ever met. He led large project the satellites he had helped to lead. Those teams harmoniously and with grace, who met him quickly counted him as a FIONA HARRISON is at the California managing difficult situations calmly and colleague, then soon after a friend. Institute of Technology, 290-17, Pasadena, wisely, but with the firmness necessary to Neil, private about his illness, worked California 91125, USA. lead a project forward. He had an infectious until shortly before his death, and many in e-mail: [email protected]