Navigator Program: exploring new worlds

NASA's Navigator Program comprises a suite of interrelated missions that will discover and characterize planetary systems and Earth-like planets around nearby stars. The missions are designed to build on each other's success, each providing an essential step forward toward the goal of discovering habitable planets and life. The missions in the Navigator Program and their relation to each other are described in this paper. Moreover, the Program is described in the wider context of international efforts in the broadening field of extrasolar planet research. Science priorities and research opportunities related to the Navigator Program are also described