Michael A'Hearn | |
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| Born | Michael Francis A'Hearn (1940-11-17)November 17, 1940 Wilmington, Delaware, United States |
| Died | May 29, 2017(2017-05-29) (aged 76) Maryland, United States |
| Alma mater | Boston College University of Wisconsin–Madison |
| Awards | Gerard P. Kuiper Prize |
| Scientific career | |
| Fields | planetary science |
| Thesis | The Polarization of Venus (1966) |
| Doctoral advisor | Arthur Code |
Michael Francis A'Hearn (November 17, 1940 – May 29, 2017) was an Americanplanetary scientist and astronomy professor at theUniversity of Maryland College of Computer, Mathematical, and Natural Sciences. He was the principal investigator forNASA'sDeep Impact/EPOXI mission, which performed the first impact of a comet.
Michael Francis A'Hearn was born on November 17, 1940 inWilmington, Delaware. He was the only child; his father worked for theInternal Revenue Service and his mother was a school teacher.[1] He grew up inBraintree, Massachusetts. His family was of Irish ancestry.[2]
He received hisB.A. in physics atBoston College (1961); he received thecum laude degree in three years.[1] He received aPh.D. inastronomy at theUniversity of Wisconsin–Madison (1966), with a thesis titledThe Polarization of Venus, advised byArthur Code.[3] In 1966, he joined the Department of Physics and Astronomy at theUniversity of Maryland; he spent there 50 years.[2][1]
In the middle of 1970s, A'Hearn became interested in comets, and start to observe them using ground-based telescopes and then space-based telescopes, including Hubble. He was one of the first researches who used "narrowband filters for measuring comets' gas production rates and for mapping the structure of the gas and dust in their comae". Using this approach he developed "the first chemical classification system, based on carbon chain molecules".[2] He aided in the development of systems for surveyingabundances in comets as well as techniques for determining the sizes of cometary nuclei which uses optical and infrared measurements.[4]
He was the principal investigator for theNASADeep Impact mission tocomet Tempel 1, and its extended phase calledEPOXI.[5] Deep Impact was first proposed to NASA in 1996, withMichael J. Belton as a PI and A'Hearn as a deputy. Belton left the project, leaving A'Hearn to lead it in 1998 proposal.[6] It was "one of the first active interplanetary experiments" that included an impactor. During the EPOXI phase, the spacecraft was sent to observecomet Hartley 2. A'Hearn was also a co-investigator onStardust-NExT mission that revisited the Tempel 1 comet after the Deep Impact's impact, and a co-i of two instruments on ESA'sRosetta mission to67P/Churyumov-Gerasimenko comet: the OSIRIS camera and Alice spectrograph.[2][7][3]
In 1984, A'Hearn initiated theInternational Halley Watch (IHW), "a worldwide undertaking designed to collect and preserve observations of comet Halley during its 1986 return". He then organized an observation campaign of theComet Shoemaker-Levy 9 collision with Jupiter in 1994.[2][1][3] He later became the PI of the Small Bodies Node (SBN) of NASA'sPlanetary Data System.[2][7] He served as a head of the AAS Publications Board in 2005-2008.[2] He was also a president of the solar-system division of theInternational Astronomical Union.[3]
A'Hearn's research showed "that comets are consolidated, primitive, loosely packed icy mud balls from the dawn of the solar system and building blocks of the planets". According to astronomer Carey M. Lisse, A'Hearn's best-known contributions are "helping to discover the presence of water ice and diatomic sulfur emission in cometary comae, introducing the Afρ geometry-independent measure of coma dust density, determining the rotation rates of comets by observing their cyanogen jets, and resolving the dark, low-albedo nature of cometary nuclei."[3]
A'Hearn supervised 18 PhD students.[2] According to Lisse, "By many counts, he trained, collaborated with, and employed more than 80% of the pre-Rosetta generation of cometary astronomers".[3]
In 1963, A'Hearn married his fellow student, Maxine Ramold; they had three sons.[2] A'Hearn was an avid sailor.[5]
He died from pancreatic cancer on May 29, 2017, at the age of 76.[2]
In June 1986, the main-belt asteroid3192 A'Hearn, discovered by American astronomerEdward Bowell at Lowell'sAnderson Mesa Station in Flagstaff, Arizona, was named after him in honor of his contributions tocometary science.[8]
A'Hearn authored over a hundred papers,[9] including more than 30 on the Comet Churyumov-Gerasimenko.[1]
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