THEMIS SRR 1 UCB/SSL, July 8-9,2003 THEMIS Science Requirements Dr. Vassilis Angelopoulos Principal...
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Transcript of THEMIS SRR 1 UCB/SSL, July 8-9,2003 THEMIS Science Requirements Dr. Vassilis Angelopoulos Principal...
THEMIS SRR 1 UCB/SSL, July 8-9,2003
THEMIS Science Requirements
Dr. Vassilis Angelopoulos
Principal Investigator
Space Sciences Laboratory
University of California, Berkeley
THEMIS SRR 2 UCB/SSL, July 8-9,2003
THEMIS primary objectives
AuroraAurora
Understand substorm onset and evolution (baseline mission, primary objective)
As a minimum: Where does substorm eruption start? (ionosphere, CD, Rx ?).
MAGNETOSPHERESO
LAR
WIN
D
EQUATORIAL PLANE
Themis overcomes:Meridional onset confinement (GBOs)
Mapping distortions (in situ probes)Global timing (GBOs-probes)
THEMIS SRR 3 UCB/SSL, July 8-9,2003
Events that comprise the substorm
CurrentDisruption
AuroralEruption
Reconnection
THEMIS SRR 4 UCB/SSL, July 8-9,2003
Flows
Primary Objectives, Goals and Means
Onset and evolution of substorms
Time History of Events (Onset)…
– Delineate cause and effect
• Measure WhenWhere
… and Macroscale Interactionsduring Substorms (Evolution)
– Coupling in the magnetosphere
• Measure plasma flows and waves
– Coupling to the ionosphere
• Measure currents and structures
Distinguishes among competing models: impartially answers a well-posed question…
Current Disruption Model
time Event
0 sec Current Disruption
30 sec Auroral Eruption
60 sec Reconnection
Reconnection Model
time Event
0 sec Reconnection
90 sec Current Disruption
120 sec Auroral Eruption
?
?Rarefaction wave
?
P1P2P3P4P5
GBO
…as implied by Themis,goddess of impartial justice
THEMIS SRR 5 UCB/SSL, July 8-9,2003
Mission elements
Probe conjunctions along Sun-Earth line recur once per 4 days over North America.
Ground based observatories completely cover North American sector; determine
auroral breakup within 1-3s …
… while THEMIS’s space-based probes determine onset of Current Disruption and
Reconnection each within <10s.
: Ground Based Observatory
THEMIS SRR 6 UCB/SSL, July 8-9,2003
First bonus: What producesstorm-time “killer” MeV electrons?
Affect satellites and humans in space
Source:
– Radially inward diffusion?
– Wave acceleration at radiation belt?
THEMIS:
–Tracks radial motion of electrons
•Measures source and diffusion
•Frequent crossings
–Measures E, B waves locally
ANIK telecommunicationsatellites lost for days to weeks
during space storm
THEMIS SRR 7 UCB/SSL, July 8-9,2003
Second bonus: What controls efficiencyof solar wind – magnetosphere coupling?
Important for solar wind energy transfer in Geospace
Need to determine how:– Localized pristine solar wind features…
– …interact with magnetosphere
THEMIS:
– Alignments track evolution of solar wind
– Inner probes determine entry type/size
THEMIS SRR 8 UCB/SSL, July 8-9,2003
Mission Science Objectives in a Nutshell
Minimummission
CSR, Table E-1
THEMIS SRR 9 UCB/SSL, July 8-9,2003
Ground Rules
Mission Level Science Adherence to requirement
Minimum mission Primary Performance floor
Primary Design driverAncillary (HF modes) Design goal
Baseline mission Secondary (Rad Belt) Design goalTertiary (Dayside) Design goal
Extended mission 3rd year baseline orbits At negligible impact if on target
Phase F mission 4th, 5th year shock/pause At negligible impact if on target
ExplicitlyincludedIn Level1Req’s