THEMIS/Science Briefing 1 NASA/HQ, 03/12/2003

TIME HISTORY OF EVENTS AND MACROSCALE

INTERACTIONS DURING SUBSTORMS (THEMIS)

RESOLVING THE PHYSICS OF ONSET AND EVOLUTION OF SUBSTORMS

Science Team

Principal InvestigatorVassilis Angelopoulos, UCB

EPO LeadNahide Craig, UCB

Program ManagerPeter Harvey, UCB

Industrial PartnerSWALES Aerospace

THEMIS/Science Briefing 2 NASA/HQ, 03/12/2003

Auroral eruptions and substorms

Auroral eruptions…

AuroraAurora

…are a manifestation ofmagnetospheric substorms

MAGNETOSPHERESO

LAR

WIN

D

EQUATORIAL PLANE

THEMIS/Science Briefing 3 NASA/HQ, 03/12/2003

Most compelling science driver

The onset and evolution of magnetospheric substorms

• SEC Objective #1: “Understand the changing flow of energy and matter through … planetary magnetospheres”

• National Academy of Sciences:“A strategic question in space physics”

SEC Objective#2: Explore fundamental physical processes of plasma systems

• SEC Objective #3: “Define origins and societal impacts of variability in SEC”

Substorms are fundamental… …and important to the US space program• …for understanding magnetospheric transport

• … for basic physics

• … for space weatherand society

THEMIS/Science Briefing 4 NASA/HQ, 03/12/2003

Events occuring during a substorm

CurrentDisruption

AuroralEruption

Reconnection

THEMIS/Science Briefing 5 NASA/HQ, 03/12/2003

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/Science Briefing 6 NASA/HQ, 03/12/2003

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/Science Briefing 7 NASA/HQ, 03/12/2003

Mission overview: Fault-tolerant design hasconstellation and instrument redundancy

D2

925

-10

@ C

CA

S

Instrument I&TUCB

Mission I&TSwales

Encapsulation

& launch

BGS

OperationsUCB

Probe instruments:ESA: Thermal plasmaSST: Super-thermal plasmaFGM: Low frequency magnetic fieldSCM: High frequency magnetic fieldEFI: Electric field

Ground

SST

ESA

EFIa

EFIs

FGM

SCM

Tspin=3s

THEMIS/Science Briefing 8 NASA/HQ, 03/12/2003

Mission providesdefinitive answer to the substorm question.

P1P2P3P4P5• Simultaneous observations in the key regions

• Ideal geometries for tens of substorms

• Data rates / time resolution exceed requirements

• Analysis tools available from Cluster, ISTP, FAST

• Experienced co-Is are leaders

on both sides of substorm controversy

• Custom event simulations aid analysis;

demonstrate closure in realistic plasma flow fields.

THEMIS/Science Briefing 9 NASA/HQ, 03/12/2003

Most important science resultand its science impact

Answers how substorms operate

– Explains how magnetospheres process solar wind energy

– Explains how auroras erupt

– Explains how a fundamentalspace weather process operates

MERCURY: 10 min EARTH: 3.75 hrs JUPITER: days

ASTROSPHERE

GALACTIC CONFINEMENT

SUBSTORM RECURRENCE:

THEMIS/Science Briefing 10 NASA/HQ, 03/12/2003

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/Science Briefing 11 NASA/HQ, 03/12/2003

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/Science Briefing 12 NASA/HQ, 03/12/2003

Progress for space science

Answers:

“How do substorms operate?”– One of the oldest and most important questions in Geophysics

– A turning point in our understanding of the dynamic magnetosphere

“What accelerates storm-time ‘killer’ electrons?”– A significant contribution to space weather science

“What controls efficiency of solar wind – magnetosphere coupling?”– Provides global context of Solar Wind – Magnetosphere interaction

THEMIS/Science Briefing 13 NASA/HQ, 03/12/2003

Aligned with all primary SEC objectives– Answers question deemed “strategic” by NAS

– Pre-requisite to space weather prediction

Fits NASA SEC vision for:– Studying dynamic Geospace interactions

– Increased spatial resolution and coverage

– Low cost, highly integrated probes

– Science and technology SEC pathfinder

Complementary with LWS, MMS, Cluster– THEMIS studies global interactions, others study local effects

– Extended THEMIS mission provides global context for MMS

Benefits to US space science program and timeliness

THEMIS/Science Briefing 14 NASA/HQ, 03/12/2003

Most important aspect for public

Fundamental mechanism in Sun-Earth interaction resolved

– Auroral eruption trigger identified in space

– Substorms, key to predicting space weather

– Mystery of how Earth’s environment processes energy blowing from Sun resolved

THEMIS/Science Briefing 15 NASA/HQ, 03/12/2003

Experienced EPO team:inspires young minds and excites public

“Student-operated NASA instruments detectspace storms affecting satellites and humans in space”

– EPO ground magnetometers at K-12 schools:

• Promote inquiry-based and theme-based instruction

• Allow hands-on student participation

Targets under-served communities:– Magnetically clean rural institutions: Tribal and Hispanic-serving

Expands on existing partnerships and resources:– FAST and RHESSI practices

– Space Grant Consortium

– Science museums

Total eclipse ’98, SF Exploratorium

SFUSD Teachers ‘01

RHESSI Solar Camp ‘00

THEMIS/Science Briefing 16 NASA/HQ, 03/12/2003

Uniqueness

Solves major long-standing question in magnetospheric physics– Self-sufficient, ideally complements current SEC line

Provides unique view of the dynamic magnetosphere– Unprecedented probe and probe/ground alignments study space-time evolution

Inspires K-12 students about space and Sun-Earth connections– Hands-on involvement of student magnetometer curators

First University-led multi-satellite project– Expands NASA partnership with Academia

– Trains scientific and technological workforce of the future

THEMIS/Science Briefing 17 NASA/HQ, 03/12/2003

Summary

Fully answers a compelling science question

Ushers a new era in magnetospheric physics

Benefits US space science program

Unique

Engages public

Inspires students

Timely: Science and technology pathfinder