I try to discover more about how the universe works, in order to advance humankind’s understanding.
Perform independent research in astrophysics and planetary science
Direct SOFIA observatory, leading to optimal documentation and archival science data from the mission.
Direct SOFIA Science Operations including Planning & Scheduling, Instrument Support, Data Processing, Outreach
Perform independent research in astrophysics and planetary science
Original research in astrophysics including comets, exoplanetary debris, protostars, supernova remnants, zodiacal light, interstellar medium, and cosmology.
2005-2010: Leader of the US Planck Data Processing Center at Caltech, responsible for generating the Early Release Compact Source Catalog for the European Space Agency Planck mission.
2001-2004: Deputy Head of Science Staff
1997-2005: Leader of the Infrared Array Camera instrument team on the Spitzer Space Telescope
Original research in astrophysics including comets, zodiacal light, interstellar medium at the Institut d'Astrophysique Spatiale
Participate in instrument commissioning and calibration for the ISOCAM instrument (in particular the CVF mode) on the European Space Agency's Infrared Space Observatory
Original research in astrophysics including zodiacal light, interstellar medium, and cosmology at NASA Goddard
Participate in instrument commissioning and calibration for the DIRBE instrument team on the Cosmic Background Explorer
Thesis title “Zodiacal Emission". Advisor Carl Heiles
American Astronomical Society, Division of Planetary Sciences, International Astronomical Union, American Geophysical Union
All, 1st Author, h-index=101, GoogleScholar
William [Bill] Reach (b. 1963) is an American astrophysicist and Senior Research Scientist at the Space Science Institute. He is known for his work on planetary science and astrophysics. Reach holds a Ph.D. in Astronomy from the University of California, Berkeley, and an A.B. in Physics from Cornell University.
Career
In 2024, Reach joined the Space Science Institute, conducting research on topics including exoplanetary debris and lunar hydration. He previously directed the SOFIA observatory, overseeing its mission to document and archive infrared astronomical data. Between 1997 and 2010, he led projects at Caltech’s Infrared Processing and Analysis Center, where he made significant contributions to infrared astronomy, including studies on comets, the zodiacal light, interstellar clouds, and calibration of the InfraRed Array Camera [REF https://ui.adsabs.harvard.edu/abs/2005PASP..117..978R/abstract] . His leadership roles extended to the US Planck Data Processing Center, where he oversaw data generation for the European Space Agency’s Planck mission, and he was part of the science team that won the 2018 Gruber cosmology prize. Earlier in his career, Reach contributed to the Cosmic Background Explorer and the Infrared Space Observatory while based in NASA Goddard and the Université Paris-Sud.
Research
Reach’s research covers a range of astrophysical phenomena:
1. Planets and debris around White Dwarfs: His studies utilize the James Webb Space Telescope to detect remnant planetary bodies around white dwarfs, providing insights into planetary systems’ end-states. Reach published the first spectrum of the infrared excess around a white dwarf star (G29-38), showing that the infrared emission arose largely from small silicate grains, likely debris from solid bodies that once comprised part of its planetary system.
2. Lunar Water: Using SOFIA, Reach worked with Paul Lucey and Casey Honniball from University of Hawaii to make groundbreaking discoveries of water molecules on the Moon, mapping its surface distribution and hypothesizing on water’s possible origin within lunar regolith.
3. Supernova remnants: Reach used infrared spectroscopy and molecular hydrogen and millimeter-wave imaging to trace the effects of supernova blast waves on molecular clouds. His mid-infrared "color" survey with the Spitzer space telescope identified molecular-interacting supernova remnants as "green", being brightest at 4.5 microns, with other colors being due to hydrocarbon molecules or ionized gas.
3. Interstellar Medium: Reach's work on “dark gas” clouds, utilizing observations from COBE, Planck and Arecibo, advances understanding of molecular gas and dust structures in diffuse clouds.
4. Cometary Debris: Reach has explored the dynamics of comet debris trails and analyzed fragmentation of comet 73P/Schwassmann-Wachmann 3 and the explosion of comet 17P/Holmes. His survey of short-period comets with the Spitzer space telescope showed that nearly all comets produce millimeter-sized debris, which is the bulk of the mass they produce.
5. Zodiacal Light and the Earth’s Circumsolar Dust Ring: Reach wrote his Ph.D. thesis on this topic (1991) and continued to study it occasionally throughout his career. His research confirmed and characterized a circumsolar dust ring along Earth’s orbit with an enahcenment in density that follows the Earth. Reach made the first convincing spectrum of the zodiacal light in the infrared, detecting the signature of silicate minerals and comparing them to material around other stars.