TASTER: Trojan ASteroid Tour, Exploration and Rendezvous, a NASA Planetary Science Summer School Mission Design Exercise

A detailed investigation of the Trojan asteroids occupying Jupiter's L4 and L5 Lagrangian points has been identified as a priority for future missions by the 2011 Planetary Science Decadal Survey. Observing these asteroids and getting clear measurements of their physical characteristics and composition may yield answers to fundamental questions relating to the early Solar System. In particular, Trojan asteroids are believed to harbor primordial material dating from the time of its formation. The source region for Trojans is still unknown; the Nice model predicts that some bodies may have originated in the primordial Kuiper belt and were subsequently scattered inward during the migration of Neptune and Uranus and settled in their current location. In alternative models, less radial scattering of small bodies would imply Trojans formed from material at a similar orbital distance to Jupiter. Determination of Trojan composition and structure will help identify their birth location, provide information about the impact history and subsequent evolution. Earth-based observations of size and surface characteristics are sparse; spectral measurements are unable to resolve composition (and show a puzzling lack of volatile signatures), indicating that close-range observation is needed. We present a mission design for a Trojan Tour and Rendezvous mission that is consistent with NASA's New Frontiers candidate recommended by the Decadal Survey, and which is the final result of the 2011 NASA-JPL Planetary Science Summer School Mission Design Exercise. Our proposed mission includes a tour phase that features a 500 km altitude fly-by of 1999 XS143. The spacecraft will then orbit and make detailed observations of 1919FD Agamemnon, a 167 km diameter asteroid located in the leading Lagrangian point (L4), from orbital altitudes of 1000 - 100 km over a 12 month nominal science data capture period. The mission's planned primary observations aim to (1) detect and identify volatile species and rock-forming elements on or just below the surface, (2) map the surface geology, and (3) determine size, shape, and rotational state. Our payload will provide unprecedented high-resolution, global dataset for the target bodies, yielding crucial information about the early history and evolution of the Solar System.