NASA's Office of Planetary Science and Astrophysics has placed the inner magnetosphere imager (IMI) third in its queue of intermediate-class Space Physics Division missions for launch in the 1990's. The George C. Marshall Space Flight Center (MSFC) is performing a concept definition study of the proposed mission. An instrument complement of approximately seven imagers will fly in an elliptical Earth orbit with a seven Earth Radii (RE) altitude apogee and approximately 4,800-km altitude perigee. Several spacecraft concepts were examined for the mission. The first concept utilizes a spin stabilized spacecraft and a complementary three-axis stabilized spacecraft. The second concept places all of the instruments on a spinning spacecraft with a despun platform. Launch options being assessed for the spacecraft range from a Delta II for the single and dual spacecraft concepts to dual Taurus launches for the two smaller spacecraft. This paper will address the mission objectives, the spacecraft design considerations, the results of the MSFC concept definition study, and future mission plans.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.