UT scientist, author to speak in Oak Ridge on asteroid discoveries
Exploring asteroids using an asteroid-orbiting NASA spacecraft will be the topic of a March 20 community lecture in Oak Ridge by a retired distinguished professor from the University of Tennessee at Knoxville.
Harry "Hap" McSween, chancellor’s professor emeritus in the UTK Department of Earth and Planetary Sciences, will present the first Richard D. "Dick" Smyser Community Lecture of 2023. It is co-sponsored by ORION and the Friends of Oak Ridge National Laboratory. FORNL established the Smyser Community Lecture series early this century in honor of Smyser, the retired founding editor of The Oak Ridger who contributed greatly to FORNL’s success. ORION is an amateur science and astronomy club centered in Oak Ridge.
The title of McSween’s talk is “Asteroid Exploration by the Dawn Spacecraft.” It will be held at 7 p.m. Monday in the City Room (A-111) of the Coffey-McNally Building at Roane State Community College’s Oak Ridge Branch Campus, 701 Briarcliff Ave. Hors d’oeuvres and non-alcoholic beverages will be served starting at 6:15 p.m.
McSween, who has degrees in chemistry and geology from the University of Georgia and Harvard University, twice served as head of the UTK Department of Earth and Planetary Sciences and as interim dean of the College of Arts and Sciences. A member of the National Academy of Sciences and fellow of the American Academy of Arts and Sciences, he is the only planetary geoscientist to have been elected president of the Geological Society of America.
According to a NASA website, “Dawn launched in 2007 on a journey that put about 4.3 billion miles on its odometer. Propelled by ion engines, the spacecraft achieved many firsts until its extended mission concluded on Oct. 31, 2018. In 2011, when Dawn arrived at Vesta, the second-largest world in the main asteroid belt, the spacecraft became the first to orbit a body in the region between Mars and Jupiter.
“In 2015, when Dawn went into orbit around Ceres, a dwarf planet that is also the largest world in the asteroid belt, the mission became the first to visit a dwarf planet and go into orbit around two destinations beyond Earth.”
In the summary of his talk, McSween mentioned several findings from the Dawn space mission on asteroids, which he described as “leftover planetary raw materials.” He wrote: “Dawn also revealed some surprises, such as the presence of water on Vesta delivered by foreign objects. Precise tracking of Dawn’s orbit allowed a model of Vesta’s interior, which is dominated by a massive iron core.
"Unlike Vesta, Ceres contains large amounts of ice, as well as alteration minerals formed by interaction of minerals with liquid water. Although no meteorites are recognized to have come from Ceres, its composition is much like carbonaceous chondrites, but more pervasively altered.
“Surprisingly, Ceres hosts cryovolcanoes that erupt brines, probably in the present day, and organic compounds have been found as well. Models of Ceres’ interior indicate a soft, muddy mantle and a rigid crust of ice, silicates and salts.”
For four decades NASA funded McSween’s research on meteorites, parts of meteors that survive passage through Earth’s atmosphere and strike the ground. Most are made of rock, but a few consist partly of iron and nickel.
McSween has published hundreds of scientific papers dealing with meteorites and their implications for understanding the formation and evolution of the solar system.
Besides the Dawn asteroid orbiter, he has been involved in other spacecraft missions – most recently as co-investigator for the Mars Exploration rovers and the Mars Odyssey orbiter.
He enjoys communicating the excitement of science to the public, and he is the author of three popular books on meteorites and planetary science. He has also written widely used textbooks in geochemistry, cosmochemistry and planetary geoscience.
This article originally appeared on Oakridger: UT scientist, author to speak in Oak Ridge on asteroid discoveries
