  As a recently recognized class of objects exhibiting apparently cometary
(sublimation-driven) activity yet orbiting completely within the main asteroid
belt, main-belt comets (MBCs) have revealed the existence of present-day ice in
small bodies in the inner solar system and offer an opportunity to better
understand the thermal and compositional history of our solar system, and by
extension, those of other planetary systems as well. Achieving these overall
goals, however, will require meeting various intermediate research objectives,
including discovering many more MBCs than the currently known seven objects in
order to ascertain the population's true abundance and distribution, confirming
that water ice sublimation is in fact the driver of activity in these objects,
and improving our understanding of the physical, dynamical, and thermal
evolutionary processes that have acted on this population over the age of the
solar system.
