The Cluster Mission: Four point observation in space · Magnetic reconnection Fundamental process...

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Graz in Graz in Space Space “, September 7 “, September 7 - - 8, 2006, Graz 8, 2006, Graz The The Cluster Mission: Cluster Mission: Four Four point point observation observation in in space space Rumi Nakamura (Institut für Weltraumforschung der österreichischen Akademie der Wissenschaften)

Transcript of The Cluster Mission: Four point observation in space · Magnetic reconnection Fundamental process...

  • „„Graz in Graz in SpaceSpace“, September 7“, September 7--8, 2006, Graz8, 2006, Graz

    TheThe Cluster Mission:Cluster Mission:FourFour point point observationobservation in in spacespace

    Rumi Nakamura(Institut für Weltraumforschung

    der österreichischen Akademie der Wissenschaften)

  • thisthis talktalk

    Earth’s magnetosphere

    Cluster: Mission, Instruments, Operation

    Data analysis, modeling

    Scientific outputs

  • SunSun--Earth ConnectionEarth Connection

    Copyright: ESA

    Solar flare and CME is the key process for driving the active solar wind, which interact with the Earth’s magnetospheric environment

  • MagnetosphereMagnetosphere

    Key question in magnetospheric physics: How is solar-wind energy processed in the magnetosphere/ ionosphere system?

    Earth’s-magnetosphere is a natural “laboratory” for space plasma physics, particularly, for plasma/field interaction at differentboundaries.

  • Magnetic reconnectionMagnetic reconnectionFundamental process in space plasma

    Anti-parallel field lines move toward one another

    Field lines are broken up at X line (‘diffusion’) and reconnected

    (slow) plasma flow ⇨ magnetic field stress ⇨ fast plasma jets

    Allows mixture of plasma otherwise frozen to the field lines

  • SubstormsSubstormsSporadic energy transfer processes involving magnetosphere and

    ionosphere as a consequence of solar wind-magnetosphere coupling

    Aurora

    Current disruptionReconnection

    Reconnection and tail current disruption in the near-Earth tail

    Energy dissipated in ionosphere

  • Cluster missionCluster mission

    Solar wind

    Magnetospheric mission: with four satellites withidentical set of instrumentsApogee: 19 RE (120,000 km)Perigee: 3 RE (17,000 km)SC separation: 200-10000 kmOrbit period: 56 h Spin period: 4s

    Time lines1982 ESA cornerstone proposal (SOHO/Cluster)1996 June Cluster I (launch failure of Ariane5) 1997 April Cluster II accepted by SPC 2000 Jul.16, Aug.9: Launch2000 Aug. 28-Dec.3: Instrument Commission 2000 Dec. 4-: Routine Operation

  • 44 Cluster instruments44 Cluster instruments

    7 DWP (H. Alleyne, UK) Wave processor

    8 EFW (M. Andre, S)Electric fields and waves

    9 STAFF (N. Cornilleau-Wehrlin, F) Magnetic and electric fluctuations

    10 WHISPER (P. Decreau, F)Electron density and

    plasma waves11 WBD (D. Gurnett, USA)

    Electric field wave-forms

    4 FGM (A. Balogh, UK)Magnetic field

    5 PEACE (A. Fazakerley, UK)Electrons (E

  • IWF mission contributionIWF mission contribution

    Data analysis in the field of space plasma physics

    Principal Investigator for potential control device(ASPOC)CoI-ship in development and construction of FluxGateMagnetometers(FGM)CoI-ship for Electron Drift Instrument (EDI), Cluster Ion Spectrometry experiment (CIS)Plasma Electron and Current Experiment (PEACE)ACDC(Austrian Cluster Data Center

  • Cluster/ASPOCCluster/ASPOC

    ASPOC (Active Spacecraft Potential Control) gewährleistet ungestörte Messungen niederenergetischer Teilchen durch Reduktion des Satellitenpotentials.

    Flüssigmetall-Ionenemitter kompensiert elektrische Aufladung des SatellitenMasse: 1,9 kgelektrische Leistung: 2,7 W

    IWF-Beitrag:FederführungElektronik

    Kooperationspartner:RSSD/ESAARC Seibersdorf, AFFI, NUNH, USA

    Elektronenzählraten PEACE

    mit ASPOC ohne ASPOC

  • Cluster/FGMCluster/FGM

    FGM (FluxGate-Magnetometer) ermöglicht Magnetfeldmessungen mit einer Auflösung von 10 pT.

    IWF-Beitrag:

    Analog/Digital-Konvertermit Interface-Elektronik

    Studie über magnetischeReinheit der Satelliten

    Sensorkalibrierung im höheren Frequenzbereich und Bestimmung des Frequenzgangs

    Kooperationspartner:

    ICL, UK (Federführung)

    NASA/GSFC, USA

    TU-Braunschweig, D

  • Cluster/EDICluster/EDI

    EDI (Electron Drift Instrument) misst das elektrische Feld und den Magnetfeldgradienten über Triangulation und Laufzeitmessung von Elektronenstrahlen.

    Messung aller drei Vektorkomponenten unbeeinflusst von lokalen Störungen in SatellitennäheGun-Detektor-Einheit:elektrische Leistung: 3,6 WMasse: 4,4 kgStrahlstrom: 0,1 µA

    IWF-Beitrag:Software

    Kooperationspartner:MPE, D (Federführung)UNH, USAUCSD, USA

  • Science data flowScience data flowReconstruction of current sheet structure from CS crossing Assume: spatial structure remains same during crossing

    Bx(t+∆τ) –Bx(t) = (dBx/dz) ∆z/∆τcurrent sheet motion

    Effective vertical scale calculation

    [Runov et al., 2004]

    first determine current sheet normal

    integrate ∆z from lobe to equator

    Z*(t) = ∫∆t dBl(t)/dt {∂Bl(t)/∂n(t)}-1 dt,

    Z*|Bx=0 =0

  • Austrian Cluster Data Austrian Cluster Data CenterCenter (ACDC)(ACDC)

  • Why four spacecraft ?Why four spacecraft ?Single point measurement cannot differentiate spatial from temporal changes. Four point measurements can determine purely spatial structure

    Spatial gradient

    Current density (∇xB; ‘curlometer’)

    Magnetic field curvature

    Plasma flow structure

    Boundary crossings

    Orientation of boundary

    Motion of boundary

    Four single-point observations(in four different plasma domains)

  • Multipoint analysis of planar structureMultipoint analysis of planar structure

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    Spatial scale of fast flowsSpatial scale of fast flowsSpatial gradient of flow obtained from sc-pairs along Y’ (and Z)

    Dawn-dusk scale: 2-3 REVertical scale: 1.5-2 RESpatial scale suggests localized source region (reconnection site)

    rate of change in velocity along Y

    dawnside edge

    dusksideedge

    dawnion measurements only at 3 SC

  • Current Sheet ProfileCurrent Sheet Profile

    JYnA/m2

    BX

    4000 km

    ab c

    d

    Z*

    Near ion diffusion region of reconnection region

    Bifurcated current sheet in Earthward fast flow region

    Thin current sheet in between(flow reversal region)

  • Spatial structure of flux ropeSpatial structure of flux rope

    Assuming pressure balance and 2D structure, plasma/field configuration around satellite trajectory can be reconstructed

    VHT = (237, 27, 23) km/s• Flux rope with half width of ~1 Re. • Strong core field (mostly By).

  • The way to go...The way to go...New mission planning

    Building SC/instrument

    Observation

    Data analysis

    New theory/modeling

    New questionsSolving problems

  • WhatWhat nextnext ??

    Magnetotail

    2009

    2005

    Cluster:

    Different years at different scales

    Additional spacecraft

    Orbit configuration changes

    Together with THEMIS (2007+):toward global scale...

    Future (2012+): MMStoward electron scale...

    Cross-scale (2015-?)

  • Future missionsFuture missionsParticipation in future NASA missions

    THEMIS (launch 2006) will probe global (and fluid) scale

    MMS (launch 2013) will probe electron (and ion) scale

    IWF contributions THEMIS: magnetometer, science def. team MMS/SMART: potential control., electric field, science def. team

    Participation in Chinese planned mission

    KuaFu magnetometer team

  • And then ?And then ?Key plasma processes

    Reconnection

    Shocks

    Turbulence

    We need to measure :

    In 3D

    On 3 scales (electron kinetic, ion kinetic, fluid)

    All 3 scales simultaneously

    Requirements

    About 12 spacecraft (3 nested groups of 4)

    Earth orbit, passing through bowshock, magnetopause and magnetotail

    Reconnection Shocks Turbulence

  • Cross ScaleCross Scale

    Many similarities to JAXA SCOPE mission

    Opportunity of a joint JAXA/ESA SCOPE/Cross-Scale mission !

    A a joint ESA/JAXA A a joint ESA/JAXA CrossCross--Scale/SCOPE Scale/SCOPE mission mission as ESA’s Cosmic Vision 2015-2025 programme ?

    Web-site http://www.crosshttp://www.cross--scale.orgscale.org//

    „Graz in Space“, September 7-8, 2006, GrazThe Cluster Mission:Four point observation in spacethis talkSun-Earth ConnectionMagnetosphereMagnetic reconnectionSubstormsCluster mission44 Cluster instrumentsIWF mission contributionCluster/ASPOCCluster/FGMCluster/EDIScience data flowAustrian Cluster Data Center (ACDC)Why four spacecraft ?Multipoint analysis of planar structureSpatial scale of fast flowsCurrent Sheet ProfileSpatial structure of flux ropeThe way to go...What next ?Future missionsAnd then ?Cross Scale