Hubble Space Telescope Observations of 2 Pallas

The material in the asteroid belt presents us with a snapshot of the earliest epoch of the solar system's formation. Telescope observations have revolutionized what we know about the largest asteroids: they are more than simple space rocks: they are evolved, dynamic bodies with important information about solar system origins. The largest asteroids 1 Ceres, 2 Pallas and 4 Vesta grew massive enough to undergo varying degrees of compositional differentiation. Ceres and Vesta will be visited by the Dawn spacecraft, but there are currently no plans for a mission to Pallas. Thus, the Hubble Space Telescope provides the best available opportunity to study Pallas. Pallas is a B-type asteroid with inclination of 31^o and estimated triaxial shape of 570x525x482 km. There is spectral evidence that Pallas, like Ceres, has been substantially altered by water. Pallas, at 2.77 AU, shares a similar environment as Ceres, but is similar in size and mass to Vesta. Thus, Pallas may provide information about how size and location affect a forming planetessimal's composition and thermal history. Planned September 3 observations of Pallas with Hubble's WFPC2 in five filters from 336-814 nm are discussed. These occur during Pallas’ opposition and include a satellite search.