Joe is a planetary scientist who studies the dynamics of planetary systems, with an emphasis on the formation and evolution of planets, satellites, planetary rings, and small Solar System bodies such as comets and asteroids. Past research activities include: Neptune's gravitational sculpting of the Kuiper Belt, numerical simulations of planet migration, and other studies of the disk-planet interactions that occur in a planet-forming disk. Joe also has expertise in the analysis of spacecraft image data, including Hubble Space Telescope images of comets, and Clementine observations of the zodiacal light, which is the sunlight that is reflected by interplanetary dust. Joe's current research activities include: analytic and numerical studies of how satellites interact with and perturb planetary rings, and modeling Hubble observations of circumstellar debris disks. Joe Hahn works from his home office in Austin, TX.