1991 UREY PRIZE LECTURE - PHYSICAL EVOLUTION IN THE SOLAR-SYSTEM - PRESENT OBSERVATIONS AS A KEY TO THE PAST

While all observations tell us about the present state of the Solar System, results from many carefully designed observational programs can illuminate and constrain models for a variety of evolutionary processes occuring over the age of the Solar System. To illustrate the power of present day observations as a key to understanding these processes, I present examples from areas covered by my own research. Major results include constraints on the sources for near-Earth asteroids and the discovery of large mainbelt asteroids fragments excavated from Vesta's surface, which give dynamical viability for Vesta as a source for basaltic achondrite meteorites. Coupling observational constraints with numerical models yields new insights on the cratering and collisional evolution among Hirayama family and other main-belt asteroids and also among the Trojan asteroids. In the outer Solar System, Pluto's surface-albedo distribution has been deconvolved from observations obtained during the unique geometry of the Pluto-Charon mutual events. Consequently, we are now working toward an understanding of Pluto's long-term seasonal evolution. © 1992.