Abstract: After 30 years of in situ measurements of the Earth's magnetosphere, scientists have assembled an incomplete picture of its global composition and dynamics. Imaging the magnetosphere from space will enable scientists to better understand the global shape of the inner magnetosphere, its components and processes. The proposed inner magnetosphere imager (IMI) mission will obtain the first simultaneous images of the component regions of the inner magnetosphere and will enable scientists to relate these global images to internal and external influences as well as local observations. To obtain simultaneous images of component regions of the inner magnetosphere, measurements will comprise: (1) the ring current and inner plasma sheet using energetic neutral atoms, (2) the plasmasphere using extreme ultraviolet, (3) the electron and proton auroras using far ultraviolet (FUV) and x rays, and (4) the geocorona using FUV. An instrument complement of approximately seven imagers will fly in an elliptical Earth orbit with a seven Earth Radii (R$-E$/) altitude apogee and approximately 4,800-km altitude perigee. Several spacecraft concepts were examined for the mission. The first concept utilizes a spinning spacecraft with a despun platform. The second concept splits the instruments onto a spin-stabilized spacecraft and a complementary three-axis stabilized spacecraft. 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 addresses the mission objectives, the spacecraft design considerations, the results of the MSFC concept definition study, and future mission plans. !6
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