The goal of any spacecraft trajectory design process is to identify a path that transfers a vehicle from its point of origin to some specific destination in the presence of path and mission level constraints. From the mission designer perspective, this process is divided into two primary tasks: (a) the identification of candidate startup arcs, and (b) the subsequent refinement of those solutions, via targeting or optimization processes, to meet some pre-defined mission requirements. The work proposed here seeks to address the first aspect directly, while addressing the second indirectly, using NASA's General Mission Analysis Tool (GMAT) as the underlying demonstration platform. Phase I of this effort is focused on developing a prototype for an Interactive Visual Analytics Tool (IVAT) for GMAT. The goal of the IVAT module is to provide a modern, interactive, preliminary design tool that allows analysts to more efficiently explore and mine the space of candidate solutions prior to selecting a specific mission for the refinement phase. The development leverages GMAT's Advanced Path Planning (APP) and Dynamical Systems Analysis Toolbox (DSAT), developed by DECISIVE ANALYTICS Corporation (DAC). IVAT is envisioned as a preliminary design tool that can be readily integrated with gradient based optimal or sub-optimal refinement tools, such as but not limited to those provided by GMAT. However, for this effort we focus on GMAT as our selected technology demonstration platform.