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-4Lake Hamana, Japan

March 12, 1998

A Simulated View of a Substorm:An IMAGE Perspective

AbstractThe Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) is NASA's first medium-sized Explorer mission and is scheduled to be launched in January 2000. 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.

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.

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

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

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

IMAGE Instruments

• Neutral Atom Imagers– 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)

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)

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)

High Energy Neutral Atom (HENA)• HENA Observations

– Neutral atom composition and energy-resolved images over three energy ranges: 10-500 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

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

Low Energy Neutral Atom (LENA)• LENA Observations

– Neutral atom composition and energy-resolved images over three energy ranges: 10-500 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

High Altitude

Low Altitude

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 130.4 nm and select 135.6 nm electron aurora emissions.

– Spectral Resolution (bottom): 121.6 nm

• Storm/substorm Observations– Image Time: 2 minutes generating 720 images/day

• Derived Quantities– Structure and intensity of the electron aurora (top)

– Structure

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

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 121.6 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

Radio Plasma Imager (RPI)• RPI Observations

– Remote sensing of electron density structure and magnetospheric boundary locations

– Measure Requirements

– Density range: 0.1-10**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

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

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 -> http::/image.gsfc.nasa.gov/