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The IMAGE Mission
J. L. Green
Goddard Space Flight Center
Presentation at The Catholic University of America
December 1, 1999
Outline
• What is the Magnetosphere?
• Geomagnetic Storms and Substorms
• IMAGE Mission Science Objectives
• Instrumentation - “Seeing the Invisible”
• Expected Accomplishments
• Summary
http://image.gsfc.nasa.gov/
Magnetospheric Currents - Quiet
Magnetopause Dynamics
• Increase solar wind pressure or reconnection can change
the position of the magnetopause by several Re
– Large scale magnetosphere reconfiguration occurs
– First indication of a geomagnetic storm or substorm will occur
• Reconnected magnetic field lines allow solar wind
plasma to enter into the magnetosphere
• A boundary layer of plasma is found Earthward of the
magnetopause
• Questions that remain to be answered:
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What is the mapping of magnetopause field lines back to the Earth?
What is the origin and dynamics of the boundary layer?
Where does solar wind plasma that enters in the magnetosphere go?
Does reconnection occur as small scale or large scale phenomena?
– Do large scale surface waves form on the magnetopause and how do they propagate?
Magnetospheric Currents - Disturbed
Ring Current
• Ring current is largely carried by ions in the 20200 keV energy range
• Ring current plasma is believed to come from both
the solar wind and the ionosphere
– Insitu measurements have found O+ is larger than H+ in large
storms
– O+ indicates ionospheric origin, H+ can be both ionospheric or solar
wind
• Questions that remain to be answered
– What is the origin of the ring current ions?
– What are the mechanisms for energization and transport into the ring
current region (L=2-7 Re)?
– What are the mechanisms for the loss of the ring current during the
storm recovery phase?
Plasmasphere Dynamics
Plasmasphere Dynamics
Plasmasphere
• Plasmasphere is made up of low energy plasma
from the ionosphere
• Plasmasphere varies in size from 5 to 2.5 Re
depending on phase of the geomagnetic storm
• Questions to be answered:
– How is the plasmpause boundary established at a new location
during a geomagnetic storm?
– What are the processes that refills or erodes the plasmasphere?
– How does the global shape of the plasmasphere evolve during
erosion and reformation?
Magnetospheric Research
• Over the last 30 years magnetospheric missions use
insitu measurements exclusively
• Auroral imagers have been our only global view of
magnetospheric dynamics
– NASA missions: ISIS (1969), DE (1982), POLAR (1996)
• Mission science objectives have been narrowly
defined to an understanding of specific plasma
regions or dynamics
• Until now there has been no mission to the “global
magnetosphere”
• Imager for Magnetopause-to-Aurora Global
Exploration (IMAGE)
– All known imaging techniques are used
– Science objectives study global phenomena and look at the
connections between individual plasma regions
Orbital Characteristics
IMAGE Instruments
• FUV Imagers
– Geocorona (GEO) imager
– Spectrographic Imager (SI)
– Wideband Imaging Camera (WIC)
• EUV Imager
– Extreme Ultra-Violet (EUV) imager
• Neutral Atom Imagers
– High Energy Neutral Atom (HENA) imagers
– Medium Energy Neutral Atom (MENA) imagers
– Low Energy Neutral Atom (LENA) imagers
• Radio Sounder
– Radio Plasma Imager (RPI)
IMAGE Spacecraft
Wideband Imaging Camera (WIC)
• The Wideband Imaging Camera is designed to
image the whole Earth and the auroral oval from
above 4 Re
• Spectral range is between 140 nm and 160 nm in
the ultraviolet part of the auroral spectrum.
• The WIC Characteristics are summarized below:
– A curved image intensifier is optically coupled to a CCD and the
optics provides a field of view of 17x17 degrees.
– Spectral range 140-160 nm
– Resolution elements of less than 0.1 degrees
– Temporal resolution 120 seconds
– 256 x 256 pixels (less than 100 km spatial resolution at apogee)
– Goal sensitivity 100 Rayleighs in final image
Spectrographic Imager (SI)
• SI is designed to image the whole Earth proton
aurora at greater than 4 Re.
• Observes at the Doppler shifted Lyman H-alpha
line at 121.82 nm in the ultraviolet part of the
optical spectrum and rejects the non-Doppler
shifted Lyman H-alpha from the geocorona at
121.567 nm.
• The SI Characteristics are summarized below:
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Doppler shifted spectral line at 121.82 nm
Field of view 15x15 degrees
Resolution elements of less than 0.15 degrees
Temporal resolution 120 seconds
128 x 128 pixels (less than 100 km spatial resolution at apogee)
Goal sensitivity 100 R in the presence of 10 kR at 121.6 nm
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
– Important input for ring current modeling in
conjunction with the neutral atom imaging
(Image at left from Rairden et al., 1986)
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
Charge Exchange Process
Generation of Neutral Atoms
Simulation of Neutral Atom Imaging
High Energy Neutral Atom (HENA)
• HENA Observations
– Neutral atom composition and energy-resolved images
over three energy ranges: 10-500 keV
• Measure Requirements
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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
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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)
High Altitude
• LENA Observations
– Neutral atom composition and energy-resolved
images over three energy ranges: 10-500 eV
• Measure Requirements
Low Altitude
– 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
Radio Plasma Imager
Radio Plasma Imager (RPI)
Principles of Radio Sounding
• Radio waves are reflected at wave cutoffs (n = 0)
• In a cold, magnetized plasma
– Ordinary (O-mode): Wave frequency = fp
– Extraordinary (X-mode): Wave frequency =
 f 
g
g
   
2
2
 
f
2
f
2
p
• Echo from reflections perpendicular to density
contours
n>0
n=0
Refracted rays
n<0
Echo
Refracted rays
Overview of Radio Plasma Imaging (RPI)
• RPI transmits coded EM waves and receives resulting
echoes at 3 kHz to 3 MHz
– Uses advanced digital processing techniques (pulse compression & spectral
integration)
• RPI uses a tri-axial orthogonal antenna system
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500 meter tip-to-tip x and y axis dipole antennas
20 meters tip-to-tip z axis dipole antenna
Transmitter can utilize either x or y or both x and y axis antennas
Echo reception on all three axes
• Basic RPI measurements of an echo at a selected frequency
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Amplitude
Time delay (distance or range from target)
Direction
Wave polarization (ordinary or extra-ordinary)
Doppler shift and frequency dispersion
• Insitu density and resonances measurements
Magnetospheric Density Structure
Representative RPI Targets
Target
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Magnetopause boundary layer
Polar Cusp
Magnetopause
Plasmapause
Plasmasphere
800
• Ionosphere
Electron Density Plasma Freq.
Range (cm-3)
Range (kHz)
5 -20 20 - 40
7 - 30 25 - 50
10 - 60 30 - 70
30 - 800 50 - 250
800 - 8x103 250 8x103 - 1x105
800 - 3000
Optimal range to reflection point 1 to 5 RE
RPI will detect these targets sufficiently often to
define their structures and motions
Ray Tracing Calculations
• Ray Tracing Code
– Developed by Shawhan [1967] & modified by Green [1976], has supported over 30
studies during the last 15 years
– Uses the Haselgrove [1955] formalism and cold plasma dispersion relations [Stix, 1992]
• Measured receiver noise level
• Three-dimensional magnetospheric plasma model
– Diffusive equilibrium plasmasphere [Angerami & Thomas, 1964]
– Plasmapause model [Aikyo & Ondoh, 1971]
– Magnetopause boundary [Roelof & Sibeck, 1993]
– With Gaussian or multi-Gaussian density profile
• Magnetopause density characteristic of MHD models
– 4 times the solar wind density at subsolar point
– 1.1 times the solar density at the dawn-dusk meridian
– Solar Wind electron density = 10 /cc
Radio Sounding
Magnetopause Echoes and Density Structure
Summary
• IMAGE is NASA’s first mission to the “global
magnetosphere”
• IMAGE uses all known remote sensing techniques
for the magnetosphere
• IMAGE will provide a unique view of how various
magnetospheric phenomena are connected
• IMAGE will provide potentially valuable space
weather data
• All IMAGE data is non-proprietary - open to
everyone!
BACKUP
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
IMAGE Telemetry Modes
• Store and forward telemetry mode
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On-board storage and high rate dump through DSN twice/day (13 hour orbit)
SMOC receives Level-0 data and generates Level-1 (Browse Product)
SMOC being developed at Goddard Space Flight Center
Data products delivered to NSSDC for archiving and community distribution
• Real-Time mode
– IMAGE broadcasts all telementry data in a real-time mode
– Data can be received by anyone
– Not routinely used by NASA
• Space Weather usage of IMAGE data by NOAA
– Will receive real-time data from several tracking stations:
 Communications Research Lab (Tokyo), U.C. Berkeley and Naval Academy
– “Space Weather” products generated and used by NOAA at SEL, Boulder
Potential IMAGE Space Weather Measurements
Imager
RPI
Data Product (Level-1)
• Plasmagram
SI
• FUV auroral image at
(121.6 nm)
• FUV auroral image (135.6
nm)
Derived Quantities
MSFM Input
• Distance to Magnetopause,
• Magnetopause
Plasmapause, Polar Cusp (when
standoff distance
observed)
• Magnetospheric shape (with model),
structure, gross irregularities
• Storm conditions from a
plasma/radio wave perspective
• Structure and intensity of the Proton • Auroral
Aurora
boundary index
• Structure and intensity of the Electron
Aurora
WIC
• Aurora Image (140-190
nm)
• Size and shape of Auroral Oval from • Polar-cap
intensities of LBH bands
potential drop
GEO
• Lyman alpha image (121.6 • Integrated line-of-sight density map
nm)
of the Earth's Geocorona
EUV
HENA
MENA
• Plasmasphere He+ image
(30.4 nm)
• Neutral atom image (10500 keV)
• Neutral atom image (1-30
keV)
LENA
• Neutral Atom Image (10500 eV)
• Echo Map
• F-T Spectrogram (1/orbit)
• Plasmaspheric density structure and
plasmaspheric processes
• Neutral atom image of composition
• Dst deduced
and energy of the Ring Current and
from GENI
near-Earth Plasma Sheet
• Both instrument data combined to
make a provisional Dst index
• Plasma Sheet and Ring Current
injection dynamics, structure, shape
and local time extent
• Neutral atom composition and energy
of the Auroral/Cleft ion fountain
• Ionospheric outflow
IMAGE Team Members
• Principal investigator: Dr. James L. Burch, SwRI
• U.S. Co-Investigators:
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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
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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:
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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
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