Public Lecture: Asteroids Ceres and Vesta Up Close: the Dawn Spacecraft Mission

“Asteroids Ceres and Vesta Up Close: the Dawn Spacecraft Mission”, an illustrated presentation by Xiaochen Mao of Washington University, will be featured at the October meeting of the St. Louis Astronomical Society. The meeting will begin at 7:30 PM on Friday, October 19, in McDonnell Hall, Room 162, on the Washington University campus, Saint Louis, MO 63130. McDonnell Hall is accessible from Forsyth Boulevard via Tolman Way. Free parking (in non-red zones) and garage visitor parking are available to the audience. The event, cosponsored by NASA's Missouri Space Grant Consortium, is open to the public free of charge.

Asteroids are small bodies of rock and metal that orbit the Sun. Most lie between the orbits of Mars and Jupiter, but some have elliptical paths that can cross Earth’s orbit.  At 583 miles across, the largest asteroid, Ceres, was discovered in 1801. The second largest, Vesta was found six years later. Although they lie in the same region of our solar system, Ceres and Vesta are quite different. Ground-based telescopes reveal few surface and composition details. NASA’s Dawn robot spacecraft, launched in 2007, provided the first close-up views.  First it traveled to Vesta, where it orbited the asteroid in 2011 and 2012. Then it moved on to Ceres, arriving in March 2015. It is now concluding its Ceres observations. Xiaochen Mao will present a brief history of the discovery of Vesta and Ceres, comment on the scientific merit of the Dawn Mission, and, discuss some of the major discoveries made by Dawn’s telescopes and instruments.

Xiaochen Mao is a fifth-year graduate student in the Department of Earth and Planetary Sciences at Washington University. His work focuses on Ceres' internal structure, revealed by modeling from its gravity field, and Ceres' spin evolution, deduced from its cratering record.