Progress toward imaging the Earth's magnetosphere

J. L. Burch (Southwest Research Institute, San Antonio, TX 78228-0510;
  (210) 522-2526; email: jburch@swri.edu)

The New Millennium Magnetosphere: Integrating Imaging, Discrete
  Observations, and Global Simulations, Sixth Huntsville Modeling Workshop,
  Guntersville, Alabama, 26-30 October 1998.


In the final words of their 1968 trilogy of papers on balloon-borne
x-rays and ground-based riometer and magnetic field measurements, Ferd
Coroniti, Bob McPherron and George Parks suggested the term
"magnetospheric substorm" to describe the global phenomena
accompanying auroral substorms. The many magnetospheric spacecraft
that have flown in the past thirty years have repeatedly validated
this pioneering suggestion. The cross-scale coupling that causes
microscale plasma phenomena to have global effects produces a dynamic
system in which variations in the time domain and the spatial domain
must be separated and in which coherent large-scale fluctuations must
be resolved. The possibility of imaging large portions of the
magnetosphere is therefore crucial to the eventual understanding of
the magnetosphere and the ability to predict its behavior. Auroral
imaging from elliptical orbits, beginning with DE-1 in 1981 and
continuing with Viking and Polar, has become indispensable in
providing global context for in-situ magnetospheric measurements.
Neutral atom imaging has been shown to be feasible with the Polar
energetic ion detector. The IMAGE instrument will progress further
with neutral atom (10 eV to 500 keV) imaging, EUV imaging of
plasmaspheric helium ions, FUV imaging of the proton aurora, and
radio plasma imaging of total plasma densities from a single spacecraft
with apogee at 7 Earth radii above the north pole. The TWINS experiment
will provide stereoscopic neutral atom images at 1 to 30 keV. Another
approach to three-dimensional imaging of the magnetosphere is to use a
constellation of hundreds of small spacecraft with plasma and magnetic
field instruments. The expected accomplishments of these various imaging
techniques will be discussed in this introductory paper.