Notable X-ray astronomy trailblazer, Professor Emeritus Hale Van Dorn Bradt, passes away at 93 years old.

Notable X-ray astronomy trailblazer, Professor Emeritus Hale Van Dorn Bradt, passes away at 93 years old.

Hale Van Dorn "Hank" Bradt, a revered X-ray astronomy pioneer and MIT emeritus professor, has left us at the age of 93. Known for his relentless pursuit of knowledge and devotion to undergraduate teaching, Bradt touched countless lives in and beyond academia.

Born on December 7, 1930, in Colfax, Washington, to a musician and an academic, Bradt's formative years were spent traversing various states, from Washington to Maine, New York City, and finally Washington, D.C., where he graduated from high school. His mother was a writer and musician, while his father was a university professor and an Army veteran who took his own life six weeks after returning home from World War II, leaving a young Bradt at 15. It wasn't until 1980 that Bradt discovered a trove of letters written by his father during the war, sparking a long-lasting research project and leading to a trilogy of books detailing his father's war experiences.

Bradt's passion for music bloomed early, as he sang in the choir and played the violin. He further nurtured his love for music at Princeton University, where he played in the orchestra and took lessons from one of his childhood teachers. In the 1960s, Bradt pursued his passion for music alongside his academic career; he played in a string quartet with MIT mathematicians and sung with the MIT Chorale Society. Even in his 80s, Bradt continued to perform with diverse amateur choruses, orchestras, and chamber groups.

Bradt's excitement for "mathematical-technical stuff" came to light during his Naval training, which he joined before his senior year in college. His unique knack for quantitative topics paved the way for his subsequent journey at MIT, where he became an integral part of the X-ray astronomy team under the guidance of Bruno Rossi.

Bradt's most notable achievements include his work as the original principal investigator for the All-Sky Monitor on the NASA's Rossi X-ray Timing Explorer (RXTE), which operated from 1996 to 2012. This mission revolutionized the understanding of X-ray emissions from celestial objects, including black holes and neutron stars, providing a 16-year record of observations. One of Bradt's most significant contributions was the discovery of X-ray pulsations from the Crab pulsar, a distant neutron star, in 1969, a finding that demonstrated the simultaneity of X-ray and optical pulses despite the vast interstellar distances between them.

Bradt's device was also instrumental in the precise celestial location and optical identification of the first stellar X-ray source, Scorpius X-1, in 1966. His group's research on X-rays originating from the Milky Way led to breakthroughs in understanding these high-energy processes in the universe.

In addition to his work with the RXTE and the All-Sky Monitor, Bradt made significant progress in understanding neutron stars, particularly their cooling mechanisms, magnetic field properties, and other aspects of their extreme astrophysical environments. Bradt's research provided crucial insights into these fascinating objects, paving the way for further investigations into neutron star physics.

With a strong personality and unwavering determination, Bradt left an indelible mark on the world of astrophysics. His relentless spirit and generosity as a mentor inspired countless students, such as Nobel laureate Andrea Ghez, who spoke of Bradt's guidance in her transition from the classroom to the research world.

In retirement, Bradt emerged as a historian and mentor, sharing firsthand accounts of the "space race" of the mid-20th century and the evolution of MIT into a major center for space research and education. Bradt's legacy at MIT endures, and he will be remembered as a pioneering researcher, devoted teacher, and inspiring mentor.

Bradt is survived by his loving wife, Dorothy Haughey (nee Haughey), his two daughters, Elizabeth Bradt Hoskins and Dorothy McCrum, two grandchildren, Benjamin and Rebecca Hoskins, two sisters, Abigail Campi and Dale Anne Bourjaily, and 10 nieces and nephews. In lieu of flowers, contributions may be made to the Salem Athenaeum, the Thomas Fellowship, or the Barbara E. Thomas Fund in support of physics graduate students at MIT.

1. Bradt's father, a university professor, was a musician and an Army veteran who tragically took his own life six weeks after returning from World War II.
2. After high school, Bradt decided to attend Princeton University, where he continued nurturing his love for music by playing in the orchestra and taking lessons from his childhood teacher.
3. In the 1960s, Bradt combined his passion for music with his academic career, playing in a string quartet with MIT mathematicians and singing with the MIT Chorale Society.
4. Bradt's commitment to undergraduate teaching was evident even before his academic career, as he pursued Navy training during his senior year in college due to his fascination with "mathematical-technical stuff."
5. Together with the guidance of Bruno Rossi, Bradt became an integral part of the X-ray astronomy team at MIT.
6. His work as the original principal investigator for the All-Sky Monitor on NASA's Rossi X-ray Timing Explorer (RXTE) revolutionized the understanding of X-ray emissions from celestial objects between 1996 and 2012.
7. One of Bradt's most significant contributions was the discovery of X-ray pulsations from the Crab pulsar in 1969, a finding that demonstrated the simultaneity of X-ray and optical pulses over vast interstellar distances.
8. Bradt's device was also instrumental in the precise celestial location and optical identification of the first stellar X-ray source, Scorpius X-1, in 1966.
9. Throughout his tenure at MIT, Bradt made substantial progress in understanding neutron stars, particularly their cooling mechanisms, magnetic field properties, and other aspects of their extreme astrophysical environments.
10. His contributions to researching high-energy processes in space earned him numerous awards, and his impact on the world of astrophysics was indelible.
11. As a mentor, Bradt inspired and guided students like Nobel laureate Andrea Ghez through her transition from the classroom to the research world.
12. In retirement, Bradt dedicated himself to sharing firsthand accounts of the "space race" of the mid-20th century and the evolution of MIT into a major center for space research and education.
13. Bradt's legacy extends beyond academia; in his memory, donations can be made to the Salem Athenaeum, the Thomas Fellowship, or the Barbara E. Thomas Fund in support of physics graduate students at MIT.

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