IMAGERS FOR THE MAGNETOSPHERE, AURORA, AND PLASMASPHERE

We present a small Explorer mission, Imagers for the Magnetosphere, Au rora, and Plasmasphere (IMAP), to provide the first global magnetosphe ric images that will allow a systematic study of major regions of the magnetosphere, their dynamics, and their interactions. The mission obj ective is to obtain simultaneous images of the inner magnetosphere (ri ng current and trapped particles), the plasmasphere, the aurora, and a uroral upflowing ions. The instruments are (1) a Low Energy Neutral Pa rticle Imager for imaging H and O atoms, separately, in the energy ran ge of similar to 1 to 30 keV, in several energy passbands; (2) an Ener getic Neutral Particle Imager for imaging H atoms in the energy range similar to 15 to 200 keV and, separately, O atoms in the energy range similar to 60 to 200 keV, each in several energy passbands; (3) an Ext reme-Ultraviolet Imager to obtain images of the plasmasphere (the dist ribution of cold He+) by means of He+ (30.4 nm) emissions; and (4) a F ar-Ultraviolet Imaging Monochromator to provide images of the aurora a nd the geocorona. All images will be obtained with time and spatial re solutions appropriate to the global and macroscale structures to be ob served. IMAP promises new quantitative analyses that will provide grea t advances in insight and knowledge of global and macroscale magnetosp heric parameters. The results expected from IMAP will provide the firs t large-scale visualization of the ring current, the trapped ion popul ations, the plasmasphere, and the upflowing auroral ion population. Su ch images, coupled with simultaneously obtained auroral images, will a lso provide the initial opportunity to globally interconnect these maj or magnetospheric regions. The time sequencing of IMAP images will als o provide the initial large-scale visualization of magnetospheric dyna mics, both in space and time.