The Magnetospheric

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The Magnetospheric Multiscale Mission Jim
Burch Southwest Research Institute San Antonio,
TX 2008 Huntsville Workshop The Physical
Processes for Energy and Plasma Transport Across
Magnetic Boundaries October 27, 2008
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Universal Significance of Reconnection

• In general, reconnection is a candidate to
  explain any phenomena exhibiting plasma heating,
  particle acceleration, magnetic field collapse,
  or magnetic topology changes. This includes
  solar, stellar and planetary magnetic fields,
  solar and stellar winds, laboratory plasmas and
  even planetary dynamos.
• Reconnection is extremely important in the
  laboratory, especially in limiting plasma heating
  in Tokamaks. Moreover, recent advances have
  allowed for laboratory experiments in the
  collisionless regime. However, the very small
  temporal and spatial scales limit the
  measurements that can be made within the
  reconnection sites.
• Remote sensing of these phenomena (particularly
  in the solar context) provides vast amounts of
  information on their scale sizes, temporal
  development, and energy transfer but
  high-resolution in-situ measurements are needed
  to determine the processes that drive
  reconnection.
• Reconnection is the most important process
  driving the Earths magnetosphere. Groundbreaking
  measurements by spacecraft such as Polar and
  Cluster, along with rapid advancements in
  numerical simulations have set the stage for a
  definitive experiment on magnetospheric
  reconnection.

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A Fundamental Universal Process
(a)
(b)
(c)
Magnetic reconnection is important in the (a)
Earths magnetosphere, (b) in the solar corona
(solar flares and CMEs) and throughout the
universe (high energy particle acceleration).
Simulations (c) guide the MMS measurement
strategy.
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Sawtooth Crashes
Sudden flattening (or crashes) of the electron
temperature profile limit plasma heating within
Tokamaks, thereby defeating their purpose. These
crashes are explained by reconnection with a
strong guide field within the device as shown in
laboratory experiments.
Yamada et al. 1994
Current Density
Reconnection Rate
Edegal et al. 2007
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Astrophysical Contexts
Crab Nebula

• Some of the most energetic phenomena in the
  universe result from supernova explosions.
• After the explosion the star collapses into a
  neutron star and often into a black hole.
• Later any nearby stars can be distorted and drawn
  into the black hole trough an accretion disk that
  is magnetically connected through reconnection to
  the black hole and neutron star.
• The transfer of angular momentum by the magnetic
  field to the neutron star results in the ejection
  of jets of material from the star.
• The neutron star can evolve into a pulsar or, in
  extreme cases, into a magnetar, which exhibits
  very energetic flare-type emissions that, by
  analogy with the solar corona, are likely
  produced by magnetic reconnection.

Magnetar
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Is it Laminar or Turbulent?
Standard Petschek model has laminar flow with
only two field lines reconnecting at a time.
Turbulent model, in which many field lines
reconnect at once may be required to explain
reconnection that rapidly progresses over vast
astrophysical distances.
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A Fundamental Universal Process
Nakamura, 2006
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Magnetospheric Multiscale Mission

• The MMS Mission science will be conducted by the
  SMART (Solving Magnetospheric Acceleration,
  Reconnection and Turbulence) Instrument Suite
  Science Team and a group of three
  Interdiscliplinary Science (IDS) teams.
• Launch is scheduled for October 2014.

http//mms.space.swri.edu
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MMS Science Objectives

• Scientific Objective Understand the microphysics
  of magnetic reconnection by determining the
  kinetic processes occurring in the electron
  diffusion region that are responsible for
  collisionless magnetic reconnection, especially
  how reconnection in initiated.
• Specific Objectives
• Determine the role played by electron inertial
  effects and turbulent dissipation in driving
  magnetic reconnection in the electron diffusion
  region.
• Determine the rate of magnetic reconnection and
  the parameters that control it.
• Determine the role played by ion inertial effects
  in the physics of magnetic reconnection.

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Important Scale Sizes
From simulations
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Need for 4 Spacecraft

• To determine processes driving reconnection we
  need to have smaller separations (down to 10 km)
  with spacecraft within the diffusion region (as
  shown).

• To identify reconnection events we need to have
  larger separations (up to 400 km) with spacecraft
  in the two inflow regions and in the two outflow
  regions (blue and red arrows).

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Orbital Phases

• MMS employs two mission phases with inclination
  of 28 deg. to optimize encounters with both
  dayside and nightside reconnection regions.

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Orbital Strategy
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Burst-Mode Data Acquisition
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Burst-Mode Data Acquisition
Tetrahedron configuration and burst data
acquisition maintained throughout region of
interest (gt 9 RE day side, gt15 RE night side).
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Burst Mode Strategy

• MMS will have two ways of capturing burst data.
• The first involves on board assessment of data
  quality, the sharing of data quality indices
  among the spacecraft, and the assignment of
  priorities to each burst data interval (2.5
  minutes on the day side and 5 minutes on the
  night side).
• The 24-Gbyte on-board memory will store 960
  minutes of prioritized burst data along with
  survey data for downlink once per orbit. The
  downlink is limited to 4 Gbits so only a small
  fraction of the burst data can be sent to the
  ground.
• The second method involves inspection of the fast
  survey data for identification of promising burst
  intervals that did not originally have a high
  enough priority for downlink. By command these
  intervals can be assigned higher priority so that
  they can be downlinked on the next pass.
• The on-board burst quality triggers involve
  parameters such as parallel electric fields,
  particle flux variability, parallel electron
  fluxes, large delta-B, high fluxes of heavy ions
  or energetic particles, etc.

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MMS Payload

• Fields (Lead Roy Torbert, UNH)
• Search Coil Magnetometer (up to 6 kHz)
• Analog Flux Gate Magnetometer (0.5 nT/10 ms)
• Digital Flux Gate Magnetometer (0.5 nT/10 ms)
• Electron Drift Instrument (E?, 0.5 mV/m, DC to 1
  Hz)
• Double-Probe E- Field (0 - 100 kHz, 0.5 mV/m
  spin-plane, 1 mV/m axial)
• Fast Plasma (Lead Tom Moore, GSFC)
• Ion Sensor (10 eV - 30 keV)
• Electron Sensor (10 eV - 30 keV)
• High time resolution (30 ms for electrons, 150 ms
  for ions) using multiple sensors with
  electrostatic scanning of FOV.
• Hot Plasma Composition (Lead Dave Young, SwRI)
• Toroidal tophat with TOF (10 eV - 30 keV H,
  He, He, O per half spin)
• RF technique to reduce proton flux by 103 to
  eliminate spillover problem.
• Energetic Particles (Lead Barry Mauk, APL)
• Flys Eye Detector (all-sky electrons and ions to
  500 keV)
• Energetic Ion Spectrometer (3D per spin with TOF
  mass analysis)
• ASPOC (Lead Klaus Torkar, IWG, Austria)
• S/C neutralization to lt4 V as on Cluster.

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MMS Spacecraft
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Theory and Modeling

• Key to the success of the SMART science plan is
  the coupling of theory and observation.
• The SMART Theory and Modeling Team has developed
  the latest and most sophisticated numerical
  models of the reconnection process.
• These models have been used to define the MMS
  measurement requirements and guide mission
  design.
• During the development phase, the models will be
  refined further, and procedures for assimilating
  the MMS data into the models will be defined.
• In the mission operations and data analysis
  phase, the Theory and Modeling team will work
  closely with the instrument scientists to ensure
  optimum science return.
• Significant additional expertise and models have
  been added with the selection of the three IDS
  teams.

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Co-Investigators and Participating Scientists
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Interdisciplinary Science Teams
PI in Bold Letters
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Summary

• MMS will conduct definitive experiments on the
  universally-important plasma physics of magnetic
  reconnection.
• The four payloads will sample reconnection
  regions with separations and data rates
  sufficient to determine the kinetic processes
  responsible for magnetic interconnection and the
  resulting conversion of magnetic energy to heat
  and particle energy.
• The most critical region to be probed is the
  electron diffusion region within which specific
  predictions about the electric fields, currents,
  and electron dynamics will be tested.
• The measurement requirements are based on
  theoretical results from the latest reconnection
  models as well as on recent measurements from
  Cluster and Polar.
• The MMS theory and modeling program will provide
  a bridge for applying the magnetospheric results
  to the broader astrophysical context.

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After MMS?
ESA Cross-Scale Mission Study
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After MMS?
ESA Cross-Scale Mission Study
MMS 10 - 400 km Cluster ion scale and larger