Deep Space 1 encounter with Comet Borrelly

Summary form only given. The Plasma Experiment for Planetary Exploration (PEPE) made detailed observations of the plasma environment of Comet Borrelly during the Deep Space I (S+DS I) flyby on September 22, 2001. Five distinct plasma boundaries have been identified on both inbound and outbound trajectories including those associated with cometary ion pickup, the comet bow shock, and the collisional transition region. All five boundaries were remarkably asymmetric with respect to the comet nucleus-Sun axis, normally thought to be an axis of symmetry. We suggest that the coma itself is offset, possibly because of well-collimated large dayside dust jets observed by the DSI MICAS camera.