ARTEMIS Science Working Team Meeting 9/14-16/2011

LUNAR PRECURSOR EFFECTS IN THE TERRESTRIAL MAGNETOSPHERE AND SOLAR WINDJasper S. HalekasSpace Sciences LaboratoryUniversity of California, Berkeley

The Lunar Space Plasma Environment: Pre-ARTEMIS

Precursor Effects in the Terrestrial Magnetosphere

All Electrons

Upgoing e- (0-15°)

Downgoing e- (165-180°)

EFI FFTSCM FFT

B Wavelets

B Field

fpfce

fci

fpfce

Spin Tone

EFI Background

Free Energy Sources: Reflected Electrons in Magnetosphere

Loss Cone

Beam

Beam + Loss Cone:Produced By CombinedMagnetic & ElectrostaticEffects Near Surface

DownwardElectric Field

Plasma Electrons Follow Magnetic Field Linesand Reflect from E & B

Secondary ElectronsAccelerated Upward

E = - UΔConverging Magnetic Field Lines above Crustal Magnetic Fields

Polarization Properties

Coherent

Parallel-Propagating

Right-Handed

• Wave properties all consistent with parallel-propagating whistlers coming down the magnetic field line towards the Moon

NarrowbandWaves propagating anti-parallel to field

EXB

EB

B0

Instability Conditions

EFI

SCW

Reduced DistributionFunctionWhistler Mode: ω/k, (ωce-ω)/k

Streaming instabilities where df/dv|| positive

Whistlers correlate with edges of loss cone: i.e. df/dvperp positive

Ions in the Mix?• Waves near fci modulate both the electron beam and the whistlers• Possible sources: Electron beam, shadowed ion distributions, bi-ion streaming

FGM Wavelets

Loss Cone Modulated

Electron Beam Modulated

Whistlers ModulatedProton & HeliumCyclotron Frequencies

ICWs?

Precursor Effects in the Solar Wind

IonsUpgoing e- (0-15°)

Downgoing e- (165-180°)

EFI FFT

SCM FFTB Wavelets

B Field

SZA of SurfaceConnection

Fitzenreiter et al., 1990

Solar

Wind

Free Energy Sources: Reflected Electrons in Solar Wind

Generalized obstacle with magnetic fieldgradient and/or electrostatic potential gradient

MagneticField

ConvectionElectric Field

Electron Trajectory

Adiabatic Reflection in dHT Frame Gives you “Ears” in Solar Wind Frame

Whistler Cyclotron Resonance Conditions

EFI

SCW

Reduced DistributionFunction(ωce-ω)/k : ω, k on whistler branch

Ion Observations

P2 Ions

P1 Ions

P1 Reduced Dist. Funct.

P1 Power Spectrum

P1 Propagation

P1 Ellipticity

Parallel-Propagating

RH, LH

Foreshock Ions

Reflected Protons

Free Energy Sources: Reflection From Crustal Magnetic Fields

Reflected Proton FluxesLue et al., 2010

Reflected ProtonsFollow PickupIon Trajectories

Solar

Wind

GyratingProtons

Distribution Near Cycloid “Cusp”

IMF

SW

Pickup Ion Trajectories

Surface Crustal Magnetic Field

ConnectedUnconnected

ReconstructedIon Trajectories

Ion Reflection Source Map

26 Event Periods, June 29 – August 31

Lunar Precursor Effects