50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132) 2225.pdf ATHENA: THE FIRST-EVER ENCOUNTER OF (2) PALLAS WITH A SMALLSAT. J. G. O’Rourke1,*, J. Castillo-Rogez2, L. T. Elkins-Tanton1, R. R. Fu3, T. N. Harrison1, S. Marchi4, R. Park2, B. E. Schmidt5, D. A. Wil- liams1, C. C. Seybold2, R. N. Schindhelm6, J. D. Weinberg6, 1School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 2Jet Propulsion Laboratory, Pasadena, CA, 3Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, 4Southwest Research Institute, Boulder, CO, 5School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, 6Ball Aerospace, Boulder, CO, *
[email protected]. Introduction: Pallas is the largest unexplored and • How have the myriad chemical and physical most off-ecliptic protoplanet in the main belt and the processes that shaped the solar system operated, parent of a populous impact family that includes many interacted, and evolved over time? near-Earth asteroids. Discovered in 1802 by serendipity • How did the current population of asteroids during the earliest observations of Ceres, Pallas is nearly evolve in time and space? the same size as Vesta. Protoplanets provide fascinating Athena makes substantial progress towards achieving examples of planetary processes like volcanism, tecton- two broad, high-level science goals: ics, and internal differentiation. Existing observations 1. Understand the role of water in the evolution hint that Pallas fills an observational gap in terms of wa- of Pallas. ter content between Vesta and Ceres—the two pro- 2. Constrain the dynamical evolution of Pallas toplanets explored by NASA’s Dawn Mission [1,2].