Origins of Outer Planet Regular Satellites
Senior Scientist: Ignacio Mosquiera
Regular satellites may provide a probe of the compositional and thermal state in the subnebula at the tail end of giant planet formation. Early models porpose the formation of satellites in the circumplanetary nebulae of Jupiter and Saturn (Pollack and Reynolds 1974: Pollack et al. 1976). These models envision a condensation sequence analogous to that of the nebula. Still, the physical conditions in the circumplanetary disks were thought to be sufficiently different from those of the nebula that a sharp contrast was drawn between objects forming in the outer nebula and giant planet subnebulae (Prinn and Fegley 1981). Yet, such ideas have retained a phenomenological character, as the nature of the interactions between the two environments has remained poorly understood. This study seeks to provide a direct physical link between planetesimals in the outer solar nebula and the circumplanetary disks of giant planets, and to account for the source of the solids that ultimately led to the formation of the regular satellites of the giant planets. For that, one must first consider the ways in which heliocentric planetesimals can be captured into permanent circumplanetary orbits, which requires a mechanism of energy loss. The objective of this proposal is to quantitatively study inelastic and gravitational collisions between heliocentric planetesimal fragments taking place within the Hill radius of the giant planet, and ablation of planetesimal fragments crossing the circumplanetary gas disk. We seek to develop basic theory and to conduct research that places the results of these outer planet missions into the larger context of bodies in the outer Solar System.