Barry Mauk,

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Untangling complex processes within Earths
radiation belts with the Radiation Belt Storm
Probes (RBSP) mission.

• Barry Mauk,
• Nicola Fox, David Sibeck,
• Shrikanth Kanekal, Joseph Grebowsky, Ramona
  Kessel
• RBSP Project Science Team

This document has been reviewed for ITAR
restrictions and is cleared for public release
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The RBSP Mission is designed to

• Objective
• Provide understanding, ideally to the point of
  predictability, of how populations of
  relativistic electrons and penetrating ions in
  space form or change in response to variable
  inputs of energy from the Sun.

• Impacts
• Understand fundamental radiation processes
  operating throughout the universe.
• Understand Earths radiation belts and related
  regions that pose hazards to human and robotic
  explorers.

Intensities of Earths dynamic radiation belts
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We have learned much about radiation belt
physics but substantial important mysteries
remain
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Two types of RBSP Goals

• Better understand individual transport and
  energization mechanisms
• Understand the extent to which non-linearities
  modify the role that whistler mode waves play in
  exchanging energy with and scattering radiation
  belt electrons.
• Untangling complex processes Better understand
  how these mechanisms act together to yield the
  complex behaviors that are observed.
• What is the relationship between processes that
  supply electron source populations and those that
  generate the Ultra Low Frequency waves that can
  help transport those particles? 
• What is the role of substorm injections in
  creating or modifying the global electric fields
  that transport and redistribute the injected
  plasma populations?
• How dependent is the wave activity that energizes
  radiation belt electrons on the global electric
  field that creates the conditions for wave
  generation?

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Example What is the importance of EMIC waves in
the control (loss) of radiation belt particles?
Courtesy A. (Sasha) Ukhorskiy
Mauk McPherron, Phys. Fluids,1980
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It has been proposed that increases in helium
concentrations stimulates EMIC wave generation
Young et al., 1981 Roux et al., Rauch et al.,
1982
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Wave modifications are so profound that mass
composition cannot be confidently determined
Mauk McPherron, Phys. Fluids,1980
Mauk and McIlwain, JGR, 1993
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Global magnetosheric structure and transport
generate the conditions for EMIC wave generation
Global convection likely plays a key role
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But, we remain profoundly ignorant of the
configuration and dynamic of convective fields
Rowland Wygant, 1998
Hori et al. 2005
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Dynamic injections appear required to explain the
transport needed to population the regions of
EMIC generation
Mauk and Meng, 1983a
Kivelson et al. 1979
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Understanding the importance of EMIC wave control
or radiation belts requires

• Improved understanding of the microphysics of
  wave generate.
• Improved understanding of the global
  electromagnetic transport processes to understand
  how the conditions for wave generation are
  created.
• Untangling complex processes within Earths
  radiation belts

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What is required to untangle complex processes?

• Simultaneous, multipoint sampling at various
  spatial scales reveals source and evolution of
  critical features.
• High quality, integrated measurements are needed
  to target key processes.

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Multiple spacecraft must target key radiation
belt regions with variable spacing

• 2 identically-instrumented spacecraft for
  space/time separation.
• Lapping rates (4-5 laps/year) for simultaneous
  observations over a range of s/c separations.

• 600 km perigee to 5.8 RE geocentric apogee for
  full radiation belts sampling.
• Orbital cadences faster than relevant magnetic
  storm time scales.
• 2-year mission for precession to all local time
  positions and interaction regions.
• Low inclination (10?) to access all magnetically
  trapped particles
• Sunward spin axis for full particle pitch angle
  and dawn-dusk electric field sampling.
• Space weather broadcast

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RBSP has unusually comprehensive particle and
fields instrument measurement capabilities
Particle Sensors PSBR/RPS ECT/REPT ECT/MagEIS RBSP
ICE ECT/HOPE
MagEIS
electrons
REPT
HOPE
protons
RPS
ion composition
RBSPICE
Energy
1eV
1keV
1MeV
1GeV
EMFISIS FGM
DC Magnetic
Fields Waves Sensors EMFISIS/MAG EMFISIS/Waves E
FW
AC Magnetic
EFW Perp 2D
DC Electric
EFW Par 1D
EMFISIS Waves
AC Electric
EFW E-field Spectra
DC 10Hz
1kHz
1MHz
Frequency
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Coordinating RBSP with other missions helps
greatly to untangle processes Example Themis
Courtesy of Sibeck Ukhorskiy
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RBSP resolves important universal science
questions that have practical consequences

• RBSP advances NASAs Strategic Plan and
  Heliospheric Science Objectives
• Fundamental science.
• Determining effects of solar variability on
  technological systems.
• Developing ability to predict extreme dynamic
  space conditions.
• Much has been learned about radiation belt
  physics but our ignorance is profound in some
  areas
• Text book predictions about key observations are
  wrong.
• Radiation belt dynamics is not understood.
• Untangling the interaction of complex processes
  is needed.
• RBSP provides the needed multi-point sampling and
  integrated measurements to make transformational
  advances in understanding.

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• Backup