NASA has recently selected a new mission called Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) as the first mid-sized explorer in magnetospheric phisycs to be launched in January 2000. IMAGE will produce forefront science by quantifying the response of the magnetosphere to the time variable solar wind. It will acquire, for the first time, a variety of three-dimensional images of the magnetospheric boundaries and plasma distributions extending from the magnetopause to the inner plasmasphere. The images will be produced on a time scale of 5 minutes which is needed to answer important questions about global solar wind and magnetosphere interactions such as magnetospheric storms and substorms.
The overall objective of IMAGE is best expressed by the question: How does the magnetosphere respond globally to the changing conditions in the solar wind? Specific questions around which the IMAGE mission has been designed are: 1) What are the dominant mechanisms for injecting plasma into the magnetosphere on substorm and magnetic storm time scales? 2) What is the directly driven response of the magnetosphere to solar wind changes? and 3) How and where are magnetospheric plasmas energized, transported, and subsequently lost during storms and substorms?