This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
Using state-of-the-art numerical simulations and present-day asteroid properties, the team led by Dr. Bottke will investigate how collisional and dynamical evolution has shaped small body populations since the end of accretion. The work follows three main themes. 1) Vesta, a 530 km diameter intact differentiated asteroid, is currently unique in the main belt, and yet evidence indicates that the primordial main belt once held as many as one thousand Vesta-like objects. Critical clues to their mysterious disappearance can be found among the basaltic, olivine-rich, and metallic fragments in the main belt today, and the team will use these surviving remnants to glean insights into the nature and evolution of the missing Vesta population. 2) The outer main belt, Hilda, and Trojan populations contain 15%, 90%, and 90% of the type of asteroid classified from spectral data as class D or P, primitive objects that closely resemble dormant comets and whose origin is controversial. Numerical simulations of the evolution of these populations to derive the nature of D/P asteroids will be used to test various origin scenarios. 3) The histories of asteroid populations are critically constrained by the existence and evolution of different asteroid families. The research tools used here include the Yarkovsky and YORP (an acronym of scientists' names) effects, which are thermal radiation forces and torques that cause asteroids to undergo orbital semi-major axis drift and spin vector modifications, respectively. This study will track the coupled dynamical effects of Yarkovsky/YORP forces along with collisional effects, to model the evolution of specific asteroid families. For individual families, the team will be able to estimate their initial velocity distributions, their ages, and whether or not they produced "asteroid showers" in the past.
The results will affect the interpretation of critical spacecraft data and will help to characterize the processes that shaped and scattered known asteroids, comets, and meteorites. The research will be included in continuing educational and public outreach work in Colorado and Wyoming elementary and high schools, and through the public and amateur astronomy media.
