Dr. Henry Hsieh's primary interest is investigating the nature of volatile material in the asteroid belt and what it can tell us about the solar system's formation and the origin of terrestrial volatiles. His primary work in this area has been in the study of active asteroids, and more specifically, main-belt comets. Along with his collaborators, he investigates these objects using targeted imaging and spectroscopic observations to physically characterize their nuclei and activity, mining of current and archival survey data to discover more such objects, dust modeling to understand the dust emission behavior for individual objects, dynamical analyses to investigate the long-term dynamical behavior of these objects and search for associations with asteroid families, and thermal modeling to better understand the evolution of the volatile content and active behavior of main-belt comets over time.