Auroral Physics at Jupiter: Radio and Plasma Wave...
Transcript of Auroral Physics at Jupiter: Radio and Plasma Wave...
Presented at LASP, 7 March 2016
W. S. Kurth, G. B. Hospodarsky
University of Iowa
Auroral Physics at Jupiter: Radio and Plasma Wave Observations by Juno
JunoScienceObjec-ves
OriginDetermineO/Hra.o(waterabundance)andconstraincoremasstodecideamongalterna.vetheoriesoforigin.
InteriorUnderstandJupiter'sinteriorstructureanddynamicalproper.esbymappingitsgravita.onalandmagne.cfields
AtmosphereMapvaria.onsinatmosphericcomposi.on,temperature,cloudopacityanddynamicstodepthsgreaterthan100barsatallla.tudes.
MagnetosphereCharacterizeandexplorethethree-dimensionalstructureofJupiter'spolarmagnetosphereandauroras.
JunoPayload
X and Ka Band Gravity Science (JPL/ASI) Six Microwave Radiometers— MWR (JPL) Magnetometer— MAG (GSFC/DTU) Camera - JunoCam (Malin) Three Energetic Particle Detectors—JEDI (APL) Four Jovian Auroral Distributions — JADE (SwRI) Waves (U of Iowa) UV Spectrometer— UVS (SwRI) IR Camera/Spec –JIRAM (ASI)
PolarMagnetosphereExplora-on
Location is Key: Juno passes directly through auroral field lines. A suite of instruments is used to understand the physics: JADE, JEDI, MAG, Waves, JIRAM, UVS
OutstandingQues-ons:PolarMagnetosphere
• Whatstructureofthepolarmagnetosphere?HowdoesitcomparetoEarth’s?
• Whereandhowareauroralpar.clesaccelerated?• Whereandhowareauroralradioemissionsgenerated?• Whatcausesthetransientpolaraurora?• Whatisthetopologyofthepolarmagne.cfield?Howmuchconnectstothesolarwindandhowvariableisthis?
• Howdointernalmagnetosphericdynamicsandsolarwindvariabilityaffectthemainaurora?
• Howdoesthepolarmagnetospherecoupletothedistantmagnetotail?
ARerBagenaletal.,SpaceSci.Rev.,2014.
OtherOutstandingQues-ons
• Howareradia.onbeltpar.clesacceleratedandwhatprocessesdrivethestructureanddynamicsoftheradia.onbelts?
• Howisthemagnetospherecoupledtothesolarwind?Howmuchmassandmomentumaretransferred?
• Whatroledoesthesolarwindplayinmagnetosphericdynamicsandhowdeepdoesitsinfluencepenetrate?
ARerBagenaletal.,SpaceSci.Rev.,2014.
Paschmannetal.(2002)
Junowillenablecomparisonswithterrestrialauroralphysics
JunoMissionPlanBaselinemission:
32polarorbits,12degreenetPerijove~5000km14dayperiodSpinning,solarpowered
OrbitalTrajectory
JunoWavesScienceObjec-ves
• Waves primary objectives: – Explore radio and plasma waves
in Jupiter’s polar magnetosphere – Examine the role of plasma waves
in the auroral acceleration region – Identify source regions for
Jupiter’s primary radio emissions and observe these in situ
• Additionally, Waves will: – Observe the structure and
dynamics of the plasmasheet – Monitor radio emissions as a
proxy for magnetospheric dynamics
– Measure dust impacts between the ring system and the atmosphere
JunoWavesOverview
InstrumentCharacteris-csSpectralCoverage 50Hz–20kHzMagne.c
SpectralCoverage 50Hz–40MHzElectric
SpectralResolu.on ~20Channels/decade
PeriapsisModeCadence 1spectrum/s
LFandMFBurstModes WaveformCapturesinallbandsto150kHztriggeredonboard
HFBurstModes Abilitytoselecta1-MHzbandincludingfce
Preamps&Electronics
SearchCoil
ElectricAntenna
Ergunetal.
PrimeWavesTargets
8
6
4
2
0
Voyager 1March 6, Day 65, 1979Start SCET 0345:32
Time :40 :50 0346:00 :10 :20
1
0
-10 10 20 30 40 50
Time (ms)
10.
1.0
0.1
A-G00-88
R = 16.0 RJ λm = -7.7E λII I = 7E
Barbosaetal.,1981
1 2 3 4 5 6 7 8BEN (BSKG)
1
2
3
4
-6
-5
-4
Log
Elec
tric
Fiel
d(V
rms/m
)
Log
Freq
uenc
y (H
z)
Day 63 64 65 66SCET 00 12 00 12 00 12 00
R (RJ) 30 25 20 15 10 5 5 10 15 20 25 30
Voyager 1, March 4 - 7, Days 63 - 65, 1979A-G00-143
fCE
CouplingtheMiddleMagnetospheretotheAurora
AuroralRadioEmissions
Zarkaetal.,2004.
Cassini RPWS September 18, Day 262, 2000
10.0
1.0
0.1
Freq
uenc
y (M
Hz)
0
2
4
6
dB
Abo
ve B
ackg
roun
d
A-G01-165-4
UTR (RJ)8I I I (E)NIo (E)
HectometricRadiation
Kilometric Radiation
Io-ControlledDecametricRadiation
000013533567
0200135210884
04001351180101
06001350253118
08001349325135
1000134838152
AuroralRadioEmissionSource
3.95 60.68 -13.34 22.77 4.17
4.21 71.24 -39.03 23.39 6.97
4.75 76.42 -59.25 0.37
18.15
5.45 82.29 -71.76 2.33
55.56
6.21 83.73 -74.20 5.32
83.86
04:00 06:00 08:00 10:00 12:00RS
Inv. LatLatLT
L
101
102
103
104
105
106
Freq
uenc
y (H
z)
10-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
V2 m
-2H
z-1
Cassini Orbit 89October 17, Day 291, 2008
Saturn Kilometric Radiation
fce
Auroral Hiss
Narrowband Z-modeEmissions
fpe
D (RS)
Z (R
S)
0 2 4 6 8
2
0
-2
-4
-6L = 25
L=30
04:00
08:00
A-G10-001
SolarWind/MagnetosphericInterac-ons
Observa-onPlanning
PJ 52016-11-30T15:52:00.001Z2016-328 16:23 to 2016-356 14:16
0. 10. 20. 30. 40. 50.
-20.
-10.
0.
10.
20.
IntermediatePeriapsisBurst
Apoapsis
PlasmaWavesinEarth’sRadia-onBelts
TerrestrialLightningWhistlers
InterplanetaryShockAssociatedwithX4.9flareon2/25/2014
• Class X4.9 flare occurred early on 25 February • Associated with coronal mass ejection • Juno/Waves observed type III solar radio
emission • Disturbance propagated to Juno as an
interplanetary shock shown here • Upstream plasma oscillations caught in Waves
burst mode.
JunoDustImpact
0. 20. 40. 60. 80. 100. 120.
0.
1×104
2×104
3×104
4×104
5×104
6×104
Juno Waves December 2, Day 336, 2011 20:38 SCET
~ 200 mV
Time (ms)
Volta
ge (d
n)
Earth-basedSuppor-ngObserva-ons• GlennOrtonisresponsiblefororganizingEarth-basedobserva.onsinsupportoftheJunomission– Amateurs– Professionals
• Specificallyforauroralphysics,professionalsupportisexpectedfrom:– HSTUV(e.g.NicholsCycle23coincidingwithJuno’sorbitinser.on)– IRTFH3
+
– GiantTelescopes:COMICS,VISIR,CanariCam(Mid-IR)
• PhilipZarkawasaskedtocoordinateground-baseddecametricradioobserva.onsunderanad-hocgroupnamed“JunoGroundRadio”:– NançayDecameterArray(France)– LOFAR(variousEuropeanloca.ons)– UTR-2,URAN1-4(Ukraine)– LWA,LWA1(USA)– TohokuU.,FukuiInst.Tech.,U.Elect.&Comm.,KochiU.(Japan)– Others
Summary
• Theexplora.onofthepolarmagnetosphereisabasicobjec.veofJuno.
• Thepolarorbitwithverylowperiapsisisidealtosurveytheexpectedauroralaccelera.onregion.
• Junohasawell-balancedpayloadallowingacomprehensiveexamina.onofauroralprocessesatJupiter
• JunoWavesinves.ga.onshouldallowcomparisonswiththeterrestrialauroralsitua.on,therebyadvancingourunderstandingofJupiter’spolarmagnetosphere.
• ArrivalonJuly4,2016!
UVSandJIRAMobserveauroralemissionsonapproach&departure
Insituinstrumentsmeasurepar-cles&fieldsover
polesandinplasmadisk
25
TheauroraisthesignatureofJupiter’sa\empttospinupitsmagnetosphere
?
?
Upward ~ OK
Downward ???
Hill; Cowley et al.,