A small interplanetary explorer spacecraft must be configured. The mission is extremely cost constrained. The spacecraft has the following attributes: Mission Design: The spacecraft is launched from an Antares launch vehicle into its cruise away from the Earth. The maximum expected Earth-Sun angle is 20 degrees. Payload: A single instrument must be accommodated. It should be pointed normal to the spin axis of the space vehicle. Its pointing requirements are moderate. The payload has a rectangular field of view of . Guidance, Navigation