The state of the terrestrial planetary magnetospheres is
determined by the transport of magnetized plasma and energetic
charged particles from the sun and the coupling of their energy
and momentum through both large scale and small scale processes into
those magnetospheres. The incoming solar wind and energetic
particles are modified by processes in the foreshock on field lines
connected to the bow shock; by the bow shock; and by processes
within the magnetosheath. Magnetic reconnection at the magnetopause
and in the tail plays a major role in the energy transfer process.
The magnetotail and the ring current provide storage reservoirs for
energy extracted from the solar wind.
Current Paradigm
- Sun produces fast and slow solar wind,
coronal mass ejections, and energetic particles
- Streams interact, coronal mass ejections
evolve; further acceleration of particles
- Southward IMF opens the door to solar wind
coupling; solar wind density and velocity also
important
- Energy stored in magnetosphere in particles
(e.g. ring current) and magnetic field (e.g.
magnetotail)
- Energy dissipated at feet of field lines; lost
down tail
- Mass from both ionosphere and solar wind
- Reconnection is important at magnetopause
and in tail
Weaknesses in Current Understanding
- Controversy over acceleration mechanisms for
solar particles
- Poor understanding of the 3D structure of
CME's and their evolution
- Poor predictive understanding of reconnection
at the dayside magnetopause or in tail current
sheet
- Very, very few observations of the high latitude,
near-cusp magnetopause
- Controversy on the cause and nature of
substorms
- Poor understanding of the causes and nature of flows
in the magnetotail.
- Parallel electric fields incorporated in only local
theories; no global paradigm
- Role of the magnetopause and tail in generating voltage
and current sources for the ionosphere and the feedback from
the ionosphere not understood.
- No advanced warning solar wind monitor and
no tail activity monitor
- Paucity of data in inner magnetosphere -
equatorial, about 4 RE
- Difficulty in seperating temporal from spatial
variation in a non-uniform, dynamic environment.
- Poor understanding of the mechanisms and morphology
of ionospheric outflow and the role of the atmosphere in these
outflows.
Measurement Objectives
- Determine magnetic topologies: solar and magnetospheric
fields
- Measure the sources: Solar wind, energetic particles
- Map the inputs: Mass, momentum, energy irradiance
- Image the global system
- Map the flow: Mass, momentum and energy
- Characterize the coupling:
atmosphere-ionosphere-magnetosphere
Current Spacecraft
- ISTP: Geotail, Wind, Polar, Fast, Soho
- Other: Sampex, Imp8, UARS, non-NASA
Future Missions
New Technology Requirements
- Miniature solar magnetic field imaging systems
- Solar Sail Capability
- Solar Sentinel Mission: 3 S/C standing at
0.95 AU
- Tail Monitor: 1 S/C "standing" in center of
tail at 40 RE
- Solar Electric Propulsion
- Revamped GTC: Reduce size of S/C;
increase volume coverage
- Spiraling magnetospheric probes
High and low inclination spiral
orbits
- Space tug
- Microsats
- Equivalent of ground-based magnetometer
chains: cheap, autonomous
- Can carry magnetometer only; can be multi-instrument
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