Judith Pipher died aged 81 on Monday 21 February 2022. She obtained her PhD in rocket infrared astronomy under Martin Harwit in 1971 at Cornell. She once said that a woman in the lab was such an anomaly at the time that she felt Harwit and his postdoc, Jim Houck, seemed to want to protect her from getting dirty rather than let her build stuff. Nonetheless, she hand-built the individual detectors and the optical filters needed for her research. Harwit recalls: “Judy’s willingness and grace in facing these difficulties, then, as well as throughout her later career, has been inspirational.” Her thesis, Rocket Submillimeter Observations of the Galaxy and Background, not only pioneered infrared astronomy, but did so in the very challenging environment of launching liquid-helium cooled telescopes on sounding rockets. These observations were among the first evidence that much of the output of very young, hot stars is absorbed by dust in the surrounding interstellar clouds and emitted in the far infrared, and that this process operates all along the plane of the Milky Way. The phenomenon has been a cornerstone for infrared astronomy ever since.

Credit: University of Rochester photo

Pipher then joined the faculty of the University of Rochester, where she spent her entire career. She continued the study of the infrared emission of H ii regions, the birthplaces for massive stars, throughout her career, along with many other scientific ‘targets of opportunity’. In parallel, she helped initiate the revolution in infrared astronomy through the use of detector arrays. Alan Hoffman had been a postdoc at Rochester before moving on to Santa Barbara Research Center (now Raytheon Vision Systems). When he left for this position, Pipher remembered telling him “If you can get me an infrared detector array, that would be great.” Hoffman came through by sneaking an array out of Santa Barbara and, with colleague Bill Forrest, Pipher developed a camera using a 32 × 32 InSb detector array. The results, from observations at Rochester’s C. E. K. Mees Observatory (which she directed from 1979–1994) were announced in 1983 and were the first example of near-infrared arrays being used successfully for astronomy. This development helped usher in the modern era of infrared astronomy, now conducted with megapixel near-infrared arrays operating at fundamental limits. Also, the connection with Hoffman established an astronomy presence in a leading manufacturer of advanced infrared detector arrays. This connection has worked immensely to the benefit of astronomy, leading to the arrays in the IRAC instrument on Spitzer (where Pipher led the short wavelength detector development team). These arrays continued to return exciting new science until the Spitzer mission was turned off in early 2020. Raytheon more recently supplied the arrays on the Mid-Infrared Instrument about to be turned on in JWST.

The IRAC detectors were Pipher’s technical focus in the 1990s. However, when Spitzer was launched in 2003, she had nominally retired to become a professor emerita so she could devote more time to research. Pipher (with Forrest and colleague Craig McMurtry) turned her attention to advancing HgCdTe detectors to high performance out to a wavelength of 13 microns. This development has also been successful and will benefit future astronomy tremendously because the detectors can be run at relatively high temperatures, reducing the cost and complication of operating in this wavelength range. For example, these arrays are central to the Near-Earth Object (NEO) Surveyor, under development to discover, track and characterize nearby asteroids that may pose a hazard to Earth. The arrays on this mission can operate at temperatures attainable through just radiating into space, without requiring a refrigerator. In 2021, Pipher led a review article on future detector development for astronomy. This is a suitable testament to her technical contributions to the tremendous growth in infrared astronomy capabilities over her career and the foundation she has laid for future astronomers to continue that growth.

However, Pipher’s impact was by no means restricted to research. When she was elected to the National Women’s Hall of Fame (2007), her colleague Nicholas Bigelow spoke of her influence: “Throughout her career, she has made major contributions to promoting women in science, both as a role model and as a teacher and research advisor. Her down-to-Earth style and her intellectual integrity set a standard of excellence for our department that has been vital to our success and to the success of our students.” As her colleague Dan Watson summarized: “through directly nurturing her close-by junior colleagues and serving as a beacon more widely, she has contributed mightily to the creation of two generations of astrophysicists.” The entire astronomical community benefited from her uniquely positive style while she was an editor for The Astrophysical Journal. It was always great news to have a paper assigned to her because she took her role seriously as a mediator between author and referee, leading to a collaborative development of improved papers. Throughout her career, Pipher was a calm and wise advisor and mentor, always speaking with a gentle lilt that called to mind her origins in Toronto, Canada.

Unsurprisingly, Pipher’s inputs were widely sought for advisory committees. For example, she served as Vice Chair of the Universities Space Research Association (USRA) Board of Trustees and as chair of the Stratospheric Observatory for Infrared Astronomy (SOFIA) Science Council. She received the Susan B. Anthony Lifetime Achievement Award from the University of Rochester in 2002. Asteroid 306128 Pipher was named in her honour. She was elected a Legacy Fellow of the American Astronomical Society in 2020. And what a legacy she has built.