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IMAGEing the Magnetosphere's Response to Solar Wind
NASA has selected Southwest Research Institute as the principal investigator institution for a major new space science mission. The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) investigation will provide the first global images of key regions of the Earth's magnetosphere as they respond to variations in the solar wind.
The magnetosphere is the region of space controlled by the Earth's magnetic field and populated with plasma -- a gas consisting of roughly equal numbers of positively and negatively charged particles -- of both solar wind and ionospheric origin. Magnetospheric behavior is strongly influenced by the solar wind, the supersonic stream of charged particles flowing out from the Sun. The most familiar manifestation of the magnetosphere's interaction with the solar wind is the aurora -- the Northern and Southern Lights. These colorful displays result from the impact of magnetospheric charged particles with the gases of the Earth's upper atmosphere. Especially spectacular auroras are associated with "space storms," magnetospheric disturbances in the solar wind. In addition to triggering intense auroral activity, geomagnetic storms can damage spacecraft, disrupt communications, and lead to power blackouts. It is thus important to understand such storms and be able to predict them.
After its launch in late 1999, the IMAGE spacecraft will enter an elliptical polar orbit that will carry it as far as 27,000 miles above the Earth's northern hemisphere. From this vantage point, IMAGE will be able to observe simultaneously changes in the magnetopause, the boundary between the magnetosphere and solar wind, the various charged particle populations within the magnetosphere, and the size and shape of the aurora. Whereas earlier spacecraft investigations have largely been limited to sampling specific regions of the magnetosphere at specific times, the two-year IMAGE mission will offer a never before seen global perspective on the behavior of the magnetosphere as a complex, dynamic system.
IMAGE will use three different experimental techniques to carry out its mission -- radio sounding, ultraviolet imaging, and neutral atom imaging. A radio sounder will probe the boundaries of the magnetosphere and the plasmasphere (a dense region of cold ionospheric plasma surrounding the Earth in the inner magnetosphere), while ultraviolet imagers will study the aurora and the structure of the plasmasphere. Global images of magnetospheric ion populations from a suite of three neutral atom imagers will yield information about magnetospheric plasma sources as well as the behavior of the inner magnetosphere under both quiet and magnetic storm conditions. The neutral atom imagers detect neutral atoms created from magnetospheric ions through a process known as charge exchange. IMAGE will be the first space science mission to employ this technique extensively over a wide range of particle energies.
The IMAGE investigation will be directed by Dr. James L. Burch, vice president of the SwRI Instrumentation and Space Research Division and IMAGE principal investigator. The Institute will lead a team of researchers from 13 U.S. and six foreign institutions selected to participate in the project. SwRI is responsible for the complete spacecraft and its operation, as well as for building one of the neutral atom imagers and the centralized instrument data processor, through which all of the instruments will communicate with the spacecraft and with the ground.
The IMAGE investigation, with a budget of $83 million, is one of two missions funded under NASA's new Medium-class Explorer (MIDEX) program.
Published in the Summer 1996 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.