Mona Kessel, NASA HQ

Contributions byJacob Bortnik, Seth Claudepierre, Nicola Fox, Shri Kanekal, Kris Kersten, Craig Kletzing, Lou Lanzerotti, Tony Lui, Barry Mauk, Joe Mazur, Robyn Millan, Geoff Reeves, David Sibeck, Sasha Ukhorskiy, John Wygant

• Short description of RBSP• Mission• Instruments

OutlineOutline

• Early Science Endeavors of RBSP• EMFISIS• EFW• ECT• RBSPICE• RPS • Coordinated Science

• BARREL• THEMIS• Theory & Modeling

• Which Physical Processes Produce Radiation Belt Enhancement Events?

• What Are the Dominant Mechanisms for Relativistic Electron Loss?

• How do Ring Current and other geomagnetic processes affect Radiation Belt Behavior?

The instruments on the two RBSP spacecraft will measure the properties of charged particles that comprise the Earth’s radiation belts and the plasma waves that interact with them, the large-scale electric fields that transport them, and the magnetic field that guides them.

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.

• 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

Sun

Space Weather & the White House

Radiation Belt Radiation Belt Storm ProbesStorm Probes

Investigation Instruments PI

Energetic Particle Composition and Thermal Plasma Suite (ECT)

Helium Oxygen Proton Electron Spectrometer (HOPE)Magnetic Electron Ion Spectrometer (MagEIS)Relativistic Electron Proton Telescope (REPT)

H. SpenceUNH

Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS)

Low-Frequency Magnetometer (MAG)High-Frequency Magnetometer and Waveform Receiver (Waves)

C. KletzingUniversity of Iowa

Electric Field and Waves Instrument for the NASA RBSP Mission (EFW)

Electric Field and Waves Instrument for the NASA RBSP Mission (EFW)

J. WygantUniversity of Minnesota

Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)

Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)

L. LanzerottiNew Jersey Institute

of Technology

Proton Spectrometer Belt Research (PSBR)

Relativistic Proton Spectrometer (RPS)D. Byers

NRO

electrons

protons

1eV 1keV 1MeV 1GeV

ioncomposition

Energy

Comprehensive Particle Measurements

Radiation beltsRing currentPlasmasphere

Comprehensive E and B Field Measurements

DC Magnetic

DC Electric

AC Magnetic

EMFISIS FGM

EFW Perp 2D

EMFISIS SCM

1kHz 1MHz

AC Electric EFW Par 1D

EFW E-fld SpectraFrequency

1mHz~DC 1Hz 10Hz

Whistler modeEMICBackground ULF

magnetosonic

1. What issues can be resolved about whistler mode interactions and their roles in electron energization and loss in the first 3 months?

2. What issues can be resolved about the large scale dynamics and structure with just the first few major geomagnetic storms?

3. What issues can be resolved about the source, structure, and dynamics of the inner (L<2) ion and electron belts in the first 3 months?

RBSP First Science RBSP First Science EndeavorsEndeavors

EMFISIS ScienceEMFISIS Science

Understand correlations between various wave modes using varying separations between the two satellites. By start of normal operations (~60 days after launch) the satellites should be well separated.

Contribution by Craig Kletzing Shprits et al.,

2006

• What wave modes happen at both satellites as a function of separation and location? What is the spatial coherence of chorus for small separation?• What is the relationships between Chorus and hiss. Is chorus the parent wave for hiss?

• Are micro-bursts on SAMPEX and BARREL correlated to chorus or other wave modes?

• Does Chorus modulate with density changes? (ECT/HOPE)

Question 1Question 1

Plasmaspheric Hiss Plasmaspheric Hiss 100Hz 100Hz few kHz few kHz

• Confined primarily to high density regions: plasmasphere, dayside drainage plumes.

• Generation mechanism not yet understood.

Shprits et al., 2006

• At high frequency (>1kHz) and low L source could be lightning

• At typical frequencies (few 100 Hz) source is likely magnetospheric

Plasmaspheric Hiss Plasmaspheric Hiss 100Hz 100Hz few kHz few kHz

Why do we care?

• Confined primarily to high density regions: plasmasphere, dayside drainage plumes.

• Generation mechanism not yet understood.

Shprits et al., 2006

• At high frequency (>1kHz) and low L source could be lightning

• At typical frequencies (few 100 Hz) source is likely magnetospheric

Hiss depletes the slot region by pitch angle scattering.

Whistler mode Chorus Whistler mode Chorus 100Hz 100Hz 5 kHz 5 kHz

Why do we care?

Shprits et al., 2006

Capable of emptying the outer belt in a day or less.

• Outside plasmasphere primarily on dawn side near equator.• Generated by electron cyclotron instability

near equator in association with injected plasmasheet electrons.• Increased intensity during substorms and recovery.

• Associated with microburst precipitation.

Major potential mechanism for electron acceleration.

EFW ScienceEFW Science

Explore the connection between large amplitude whistler waves and microburst precipitation.

Contribution by John Wygant, Kris Kersten

Question 1Question 1

Contribution by John Wygant, Kris Kersten

• Santolik, et al. (2003) - first report of large amplitude chorus elements• Lower band chorus (<0.5fce) wave electric fields approaching 30mV/m

Large Amplitude Whistler

• Brief (<1s) increases in the flux of precipitating MeV electrons, first satellite observations by Imhof, et al. (1992).

• Usually observed near dawn, but may extend from near midnight past dawn.

• Most commonly observed from L~4–6.

EFW ScienceEFW ScienceExplore the connection between large amplitude whistler waves and microburst precipitation.

Contribution by John Wygant, Kris Kersten

Large Amplitude Whistler Occurrence

Lorentzen et al., 2001

Microburst precipitation occurrence

Statistically the connection is strong.Cully et al., 2008

Question 1Question 1

ECT ScienceECT ScienceWhy do the radiation belts respond so differently to different storms?

Contribution by Geoff Reeves

Some geomagnetic storms can:(a) Cause dramatic radiation belt enhancement;(b) Deplete radiation belt fluxes;(c) Cause no substantial effect of flux distributions;(a

)

(b)

(c)

[Reeves et al., 2003]

Question 2Question 2

ECT ScienceECT ScienceIdentify the processes responsible for the precipitation and loss of relativistic and near relativistic particles, determine when and where these processes occur, and determine their relative significance.

Contribution by Geoff Reeves

Expected Electron DistributionsQuick Science Study: Comparison of theory and observations for characteristic signatures of EMIC wavesCompare PSD as a function of E and PA during a dropout.

Do observations show expected signatures?

2D Energy-pitch angle diffusion model at fixed L

2D Energy-pitch angle diffusion model at fixed L

Li et al., 2007

Question 2Question 2

RBSPICE ScienceRBSPICE Science

If we have some geomagnetic storms during the first few months of RBSP operation, then we can address the following question.• How is current density from protons, helium ions, and

oxygen ions compared during weak and strong geomagnetic storms?

H+

O+

Energy density of oxygen ions can dominate that of protons during intense geomagnetic storms

Contribution by Tony Lui

Hamilton et al., 1988

Question 2Question 2

RPS ScienceRPS Science

Discovery: What is the energy spectrum of the inner belt protons?

Contribution by Joe Mazur

Example of the wide variation in modeled inner belt spectra

Few satellites have spent significant time near the magnetic equator and at the peak intensities of the inner belt.

AP8 MIN: Sayer & Vette 1976; AD2005: Selesnick, Looper, & Mewaldt 2007

• Ion energy spectrum is known to extend beyond 1 GeV, but the spectral details are not well established: shape, maximum energy, time dependence

• Electron spectrum unknown. How do electrons get to the inner belt?

The dominant source for protons above ~50 MeV in the inner belt is the decay of albedo neutrons from galactic cosmic ray protons that collide with nuclei in the atmosphere and ionosphere (Cosmic Ray Albedo Neutron Decay, or CRAND).

Question 3Question 3

BARREL MissionBARREL Mission

Contribution by Robyn Millan

The proposed investigation will address the RBSP goal of, "differentiating among competing processes affecting precipitation and loss of radiation particles" by directly measuring precipitation during the RBSP mission.

• Launch 20 balloons each in January 2013 and January 2014 from Antarctica.

• BARREL will simultaneously measure precipitation over 8-10 hours of magnetic local time.

• Combine the measurements of precipitation with the RBSP spacecraft measurements of waves and energetic particles.

BARREL/RBSP Coordinated ScienceBARREL/RBSP Coordinated Science

What is the loss rate due to precipitation versus magnetopause losses?

• RBSP: measure changes in in-situ trapped electron intensity

• BARREL: quantify precipitation at range of local times

• THEMIS: magnetopause losses

Contribution by Robyn Millan

Motivation: Recent results of Turner et al., 2012 (magnetopause shadowing) vs earlier results from e.g., Selesnick 2006, O’Brien 2004 (precipitation).

Figure courtesy of A. Ukhorskiy

RBSP

THEMIS

Measurements

Question 1Question 1

THEMIS/RBSP Coordinated ScienceTHEMIS/RBSP Coordinated Science

Contribution by David Sibeck

First Planned Science Campaign Science Objectives:

THEMIS has 4-8-12 hours separation of the 3 satellites along the orbit.

• What are the cause(s) of dawn-dusk differences in ion fluxes during geomagnetic storms?

•

• What role does the Kelvin-Helmholtz instability play in particle energization, transport, and loss?

•

• What are the relative roles of EMIC waves in the dusk magnetosphere, chorus waves in the dawn magnetosphere, and hiss deep within the magnetosphere?

Question 2Question 2

Coincident observation of chorus and hiss on THEMIS

• 1 inside plasmasphere, 1 outside plasmasphere

• Plasma wave instruments, recording simultaneously

• High resolution, correct frequency range

• Correct spatial regions, day side, ~equator

• Geomagnetic activityOctober 4th, 2008

Contribution by Jacob Bortnik

Question 1Question 1

Theory & Simulation/RBSP Coordinated Theory & Simulation/RBSP Coordinated ScienceScience

Chorus - Chorus - HissHissBortnik et al. [2009]

Contribution by Jacob Bortnik

Wave burst mode, 64-bin FFT, 20 Hz-4 kHz, every 1s

THEMIS-E: discrete chorus, 600 Hz- 3 kHz, 0.2-0.5 f/fce, 30-60

Average spectral time-series, 1.2 – 1.6 kHz, high correlation!

THEMIS-D: incoherent hiss, <2 kHz

Numerical Ray Numerical Ray tracingtracing

Ray trace all rays in allowable wave normal angles,

~ -50 to -45, L=6 waves reflect toward lower L and propagate into plasmasphere

Timescale : 1 s, enter plasmasphere, 2 s, 1st EQ crossing 3.2 s, magnetospheric reflection 7.7 s, second EQ crossing 20 s completely damped

Bortnik et al. [2008]

Contribution by Jacob Bortnik

Theory & Simulation/RBSP Coordinated Theory & Simulation/RBSP Coordinated ScienceScience

Question 2Question 2

• ECT: measure changes in in-situ trapped electron intensity

• EMFISIS: measure magnetic field (FFT to generate ULF wave power)

Measurements

• Global MHD (LFM) : simulate magnetospheric ULF waves driven by dynamic pressure fluctuations

Simulation

• Radial Diffusion : transport elecrons across drift shells

Theory & Modeling

Contributions by Seth Claudepierre & Sasha Ukhorskiy

Effect of ULF waves on radiation belt electrons

Pressure fluctuations In High Speed Stream excite magnetosphere

(Pc 5 frequency range)

Contribution by Mona Kessel

Kessel, 2007

SW

Contribution by Seth Claudepierre

Solar wind dynamic pressure fluctuations can drive compressional

ULF waves on the dayside

LFM SimulationDriving frequency 10 mHz

Claudepierre, 2010

that can excite toroidal mode FLRs.

Eigenfrequency Profiles

Non-diffusive Transport

Radial transport across the outer belt can be driven by a variety of ULF waves induced by SW and ring current instabilities. Transport exhibits large deviations from radial diffusion, which may account for the observed nonlinear response of electron fluxes to geomagnetic activity: even similar storms can produce vastly different radiation levels across the belt .

Ukhorskiy 2009Contribution by Sasha Ukhorskiy

Solar Wind driven Solar Wind driven ULF waves lead to ULF waves lead to non-diffusive non-diffusive transporttransport

Radial transport in MHD field model dominated by drift resonant interactions, each producing large coherent displacement of the distribution.

RBSP launch Aug 23, 2012

RBSP team and the science community

ready to get the data and *change* the theories.