1. A Simulated View of a Substorm: An IMAGE Perspective
J. L. Green, D. L. Gallagher, S. F. Fung,
M.-C. Fok, T. E. Moore, G. R. Gladstone,
G. R. Wilson, J. D. Perez, W. Calvert, P. H. Reiff
International Conference on Substorms-4
Lake Hamana, Japan
March 12, 1998

2. Abstract
The Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) is NASA's first medium-sized Explorer mission and is scheduled to be launched in January The overall science objective of IMAGE is to determine the global response of the magnetosphere to changing conditions in the solar wind. The science payload for IMAGE consists of instrumentation for obtaining images of plasma regions in the Earth's magnetosphere. The four types of imaging techniques used by IMAGE are: neutral atom imaging (NAI), far ultraviolet imaging (FUV), extreme ultraviolet imaging (EUV), and radio plasma imaging (RPI). The IMAGE instruments will make concurrent global-scale images providing researchers with an opportunity to readily observe the structure and dynamics of the plasmasphere, ring current, aurora, geocorona, and the magnetopause within a substorm.
The IMAGE mission is being designed to generate browsable images from each of its instruments on approximately a 4 minute time scale. Using appropriate models we will simulate what users of IMAGE data should expect to see during a substorm. It is anticipated that IMAGE should be able to illuminate the global development of magnetospheric substorm dynamics.

3. Mission Science Objectives
What are the dominant mechanisms for injecting plasma into the the magnetosphere on substorm and magnetic storm time scales?
What is the directly driven response to the magnetosphere to solar wind changes?
How and where are magnetospheric plasmas energized, transported, and subsequently lost during storms and substorms?
The IMAGE mission addresses these objectives in unique ways using imaging techniques.

4. IMAGE Team Members Principal investigator: Dr. James L. Burch, SwRI
U.S. Co-Investigators:
Prof. K. C. Hsieh & Dr. B. R. Sandel, University of Arizona
Dr. J. L. Green & Dr. T. E. Moore, Goddard Space Flight Center
Dr. S. A. Fuselier, Lockheed Palo Alto Research Laboratory
Drs. S. B. Mende, University of California, Berkeley
Dr. D. L. Gallagher, Marshall Space Flight Center
Prof. D. C. Hamilton, University of Maryland
Prof. B. W. Reinisch, University of Massachusetts, Lowell
Dr. W. W. L. Taylor, Raytheon STX Corporation
Prof. P. H. Reiff, Rice University
Drs. D. T. Young, C. J. Pollack, Southwest Research Institute
Dr. D. J. McComas, Los Alamos National Laboratory
Dr. D. G. Mitchell, Applied Physic Labortory, JHU

5. IMAGE Foreign Co-Is Foreign Co-Investigators
Dr. P. Wurz & Prof. P. Bochsler, University of Bern, Switzerland
Prof. J. S. Murphree, University of Calgary, Canada
Prof. T. Mukai, ISAS, Japan
Dr. M. Grande, Rutherford Appleton Laboratory, U.K.
Dr. C. Jamar, University of Liege, Belgium
Dr. J.-L. Bougeret, Observatoire de Paris, Meudon
Dr. H. Lauche, Max-Planck-Institut fur Aeronomie

6. Other Team Members Participating Scientist:
Dr. G. R. Wilson, University of Alabama Huntsville
Drs. A. L. Broadfoot & C. C. Curtis, University of Arizona
Dr. J. D. Perez, Auburn University
L. Cogger, University of Calgary, Canada
Drs. R. F. Benson & S. F. Fung, Goddard Space Flight Center
Dr. W. Calvert, University of Massachusetts, Lowell
Drs. A. G. Ghielmetti, Y. T. Chiu, M. Schulz, & E. G. Shelley, Lockheed
Dr. J. M. Quinn, University of New Hampshire
Dr. J. Spann, Marshall Space Flight Center
Prof. J.-C. Gerard, University of Liege, Belgium
Dr. G. R. Gladstone, Southwest Research Institute
Dr. D. L. Carpenter, Stanford University

7. IMAGE Instruments Neutral Atom Imagers FUV Imagers EUV Imager
High Energy Neutral Atom (HENA) imager
Medium Energy Neutral Atom (MENA) imager
Low Energy Neutral Atom (LENA) imager
FUV Imagers
Spectrographic Imager (SI)
Geocorona (GEO) imager
Wideband Imaging Camera (WIC)
EUV Imager
Extreme Ultra-Violet (EUV) imager
Radio Sounder
Radio Plasma Imager (RPI)

8. IMAGE Data and Orbit
Orbit:90° inclination, 7 RE x 1,000 km altitudeimulations illustrate instrument measurements for the magnetic cloud event of October 18-20, 1995
Actual Dst measurement shows the storm sequence
Red dots show spacecraft location (top) and state of the ring current (bottom)

9. Neutral Atom Imaging (NAI)
Earth’s Geocorona (cold neutral hydrogen) and Ring Current interact through charge exchange
During quiet times (top) the NAI fluxes are low
During storm time (bottom) NAI flux enhancements allow the tracking of storm development (spatial and temporal)

10. High Energy Neutral Atom (HENA)
HENA Observations
Neutral atom composition and energy-resolved images over three energy ranges: keV
Measure Requirements
FOV: 90°x 120°
Angular Resolution: 4°x 4°
Energy Resolution (E/E): 0.8
Sensitivity: Effective area 1 cm**2
Storm/substorm Observations
Image Time: 2 minutes generating 720 images/day
Derived Quantities:
Neutral atom image of composition and energy of the Ring Current and near-Earth Plasma Sheet
HENA/MENA instrument data combined to make a provisional Dst index
Plasma Sheet and Ring Current injection dynamics, structure, shape and local time extent

11. Medium Energy Neutral Atom (MENA)
MENA Observations
Neutral atom composition and energy-resolved images over three energy ranges: 1-30 keV
Measure Requirements
FOV: 90°x 107°
Angular Resolution:4°x 8°
Energy Resolution (E/E): 0.8
Sensitivity: Effective area 1 cm**2
Storm/substorm Observations
Image Time: 2 minutes generating 720 images/day
Derived Quantities:
Neutral atom image of composition and energy of the Ring Current and near-Earth Plasma Sheet
HENA/MENA instrument data combined to make a provisional Dst index
Plasma Sheet and Ring Current injection dynamics, structure, shape and local time extent

12. Low Energy Neutral Atom (LENA)
High Altitude
LENA Observations
Neutral atom composition and energy-resolved images over three energy ranges: eV
Measure Requirements
Angular Resolution: 8°x 8°
Energy Resolution (E/E): 0.8
Composition: distinguish H and O in ionospheric sources, interstellar neutrals and solar wind.
Sensitivity: Effective area > 1 cm**2
Storm/substorm Observations
Image Time: 2 minutes (resolve substorm development) generating 720 images/day
Derived Quantities:
Neutral atom composition and energy of the Auroral/Cleft ion fountain
Ionospheric outflow
Low Altitude

13. Spectrographic Imager (SI)
SI Observations
Far ultraviolet imaging of the aurora
Image full Earth from apogee
Measurement Requirement
FOV: 15°x 15° for aurora (image full Earth from apogee),
Spatial Resolution: 90 km
Spectral Resolution (top): Reject nm and select nm electron aurora emissions.
Spectral Resolution (bottom): nm
Storm/substorm Observations
Image Time: 2 minutes generating 720 images/day
Derived Quantities
Structure and intensity of the electron aurora (top)
Structure

14. Extreme Ultra-Violet (EUV) imager
EUV Observations
30.4 nm imaging of plasmasphere He+ column densities
Measure Requirements
FOV: 90°x 90° (image plasmasphere from apogee)
Spatial Resolution: 0.1 Earth radius from apogee
Storm/substorm Observations
Image Time: 10 minutes generating 144 images/day
Derived Quantities:
Plasmaspheric density structure and plasmaspheric processes

15. Geocorona (GEO) Imager
GEO Observations
Far ultraviolet imaging of the Earth’s Geocorona
Measurement Requirement
FOV: 1° x 360° for Geocorona
Spatial Resolution: 90 km
Spectral Resolution:Lyman alpha nm
Storm/substorm Observations
Image Time: 2 minutes generating 720 images/day
Derived Quantities
Integrated line-of-sight density map of the Earth’s Geocorona
Not shown in the IMAGE Movie
Image at left from Rairden et al., 1986

16. Radio Plasma Imager (RPI)
RPI Observations
Remote sensing of electron density structure and magnetospheric boundary locations
Measure Requirements
Density range: **5 cm-3 (determine electron density from inner plasmasphere to magnetopause)
Spatial resolution: 500 km (resolve density structures at the magnetopause and plasmapause)
Storm/substorm Observations
Image Time: 3 minute (resolve changes in boundary locations) generating 480 plasmagrams/day
Quantity Simulated is an RPI “echo map”
Illustrates spatial location and intensity of return echoes (plotted as ray miss distance)
Doppler measurement (not shown) provides key information on boundary motion
Echoes from a large scale surface waves on the magnetopause

17. Simulated RPI Plasmagram
RPI browse product data will produce plasmagrams
Echoes shown in solid line, density features in dashed line.
Derived Quantities from Plasmagrams include:
Distance to Magnetopause, Plasmapause, Polar Cusp (when observed)
Magnetospheric shape (with model), structure, gross irregularities
Storm conditions from a plasma/radio wave perspective

18. Summary
IMAGE will be launched in January 2000 just before solar maximum
All instruments on IMAGE will provide unique global images of magnetospheric storm & substorm dynamics
Proton and Electron Aurora
Ring Current distribution and a provisional Dst (see Jorgensen et. al, 1997)
Electron density structures and magnetospheric boundary locations (plasmapause, cusp, etc.)
Geocorona and He+ plasmaspheric distributions
For more details see ->