SALEM - Mr. Hale Van Dorn Bradt, 93, of Peabody, formerly of Salem and Belmont, beloved husband of Dorothy A. (Haughey) Bradt, passed away on Thursday, November 14th, 2024 at Salem Hospital surrounded by his loving family.

Hale was born in Colfax, Washington, on Dec. 7th, 1930, and was raised in Washington State, Maine, New York City, and Washington, D.C., where he graduated from high school. He graduated from Princeton University in 1952 with a major in music. During the Korean conflict, he served in the US Navy as a deck officer and navigator on a navy cargo ship, the USS Diphda, after which he earned a PhD in physics from Massachusetts Institute of Technology, MIT, in 1961. Subsequently he served for 40 years on the MIT faculty as Professor of Physics, working primarily in x-ray astronomy with NASA rockets and satellites until his retirement in 2001. Much of his research was directed toward determining the precise locations of celestial x-ray sources, most of which were neutron stars or black holes. This made possible investigations of their intrinsic natures at optical, radio, and x-ray wavelengths. At MIT he taught undergraduate courses in physics and astrophysics and was awarded the 1990 Buechner Teaching Prize of the Department of Physics.

Bradt lived with his family for many years in Belmont, MA, from 2004 – 2022, in Salem, MA, and from 2022 in Peabody, MA. He was an avid small boat sailor in his 30s and 40s and was active as a violinist and choral singer through most of his life. He and Dorothy were members of the Paul Madore Chorale.

Bradt's initial research was with Bruno Rossi's cosmic ray group at MIT in the study of extensive air showers (EAS) on Mt. Chacaltaya in Bolivia. Searches for EAS with gamma-ray primaries (as low-mu showers) were unsuccessful. In 1966 he participated in the rocket experiment (led by Herbert Gursky) that led to the celestial location and optical identification of the first stellar x-ray source, Scorpius X-1. In 1967, he initiated MIT's sounding rocket program in x-ray astronomy and, with his group, independently discovered x-ray pulsing from a spinning neutron star, the Crab pulsar. His results uniquely demonstrated the near simultaneous arrival times (within a millisecond) of the optical and x-ray pulses, after 5000 years of travel through interstellar space.

Bradt was a senior participant or a principal investigator for instruments on the NASA x-ray astronomy satellite missions, SAS-3 (launched 1975), HEAO-1 (1977), and RXTE (1995). He received NASA's Exceptional Scientific Achievement Medal in 1978 for his contributions to the HEAO-1 mission and shared the 1999 Bruno Rossi Prize of the American Astronomical Society's (AAS's) High Energy Astrophysics Division for his role in bringing to fruition the Rossi X-ray Timing Explorer (RXTE) mission, which detected, by design, x-ray signals (kilohertz oscillations) from the immediate environs of neutron stars and black holes. He was the principal investigator (until 2001) of the All Sky Monitor on the RXTE mission, which provided unprecedented 16-year light curves of several hundred x-ray sources, including galactic microquasars, which reveal the mechanisms of jets in the much more massive, but more distant extragalactic quasars. He was proud of the numerous young scientists, students and associates, who prospered in part because of the opportunities he provided them.

Bradt served as secretary-treasurer (1973 – 1975) and chairman (1981) of the High Energy Astrophysics Division of the AAS and on the National Academy of Science's Committee for Space Astronomy and Astrophysics from 1979 to 1982. He became a Legacy Fellow of the AAS in 2020.

After retiring from MIT, Bradt served for 16 years as academic advisor for MIT's McCormick Hall freshmen for which he received MIT Advising Awards in 2004 and 2017. He served as a trustee of his condominium for nine years. He published two astrophysics textbooks, Astronomy Methods (2004) and Astrophysics Processes (2008), the latter of which received the 2010 Chambliss Astronomical Writing Prize of the AAS, two versions of a memoir, Wilber's War (2016 – 17), based on his father's letters written during World War II, and Chasing Black Holes (2021) about the RXTE mission. A favorite activity was his role in the care and restoration of an historic street clock in Salem, MA.

Bradt is the son of the late Lt. Col. Wilber E. Bradt and Norma Sparlin Bourjaily, and is survived by his wife, Dorothy Haughey Bradt, whom he married in 1958; two daughters and their husbands, Elizabeth Bradt and her husband, J. Bartlett "Bart" Hoskins of Salem, MA, and Dorothy McCrum and her husband, Bart McCrum of Buxton, ME; two grandchildren, Benjamin and Rebecca Hoskins; two sisters, Abigail Campi of Delray Beach, FL, and Dale Anne Bourjaily of The Netherlands, and ten nieces and nephews. He was predeceased by his sister, Valerie Hymes.

ARRANGENENTS: At the request of the family all services are private. Assisting the family with the arrangements is O'Donnell Cremations – Funerals – Celebrations, 84 Washington Sq., (at Salem Common) SALEM.  Expressions of sympathy may be made to Salem Athenaeum, 337 Essex St., Salem, MA 01970. To share a memory or offer a condolence, please visit www.odonnellfuneralservice.com.

Salem Athenaeum
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