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All images credit: NASA / JPL / Brown University. Evdokimova N., Korablev O., Marchenkov K., Rodin A ., Malova H., Podzolko M., Zelenyi L. Space Research Institute(IKI), Moscow, Russia. Jupiter system. Jupiter has ~50 satellites!.

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slide1
All images credit: NASA / JPL / Brown University

Evdokimova N., Korablev O., Marchenkov K., Rodin A., Malova H., Podzolko M., ZelenyiL.

Space Research Institute(IKI), Moscow, Russia

jupiter system
Jupiter system

Jupiter has ~50 satellites!

1. Io 2. Europa3. Ganymede 4. Callisto 5. Amalthea6. Himalia7. Elara8. Pasiphae 9. Sinope10. Lysithea11. Carme12. Ananke13. Leda 14. Thebe 15. Adrastea16. Metis17. Callirrhoe18. Themisto19. Megaclite20. Taygete21. Chaldene22. Harpalyke23. Kalyke24. Iocaste25. Erinome

26. Isonoe27. Praxidike28. Autonoe29. Thyone30. Hermippe31. Aitne32. Eurydome33. Euanthe34. Euporie35. Orthosie36. Sponde37. Kale 38. Pasithee39. Hegemone40. Mneme41. Aoede42. Thelxinoe43. Arche44. Kallichore45. Helike46. Carpo47. Eukelade48. Cyllene49. Kore50. Herse

Ио

Каллисто

http://physics.fortlewis.edu/Astronomy

galilean satellites of jupiter
Galilean Satellites of Jupiter

Four Galilean satellites – since 1610

Jupiter has ~50 satellites!

MGS view. Image credit: NASA / JPL

Ио

1:2:4 Laplace resonance

Io

Europa

http://physics.fortlewis.edu/Astronomy

Ganymede

Callisto

http://physics.fortlewis.edu/Astronomy

activity of galilean satellites
Activity of Galilean satellites

Io

Europa

Ganymede

Callisto

Magmatism

Tectonism

Impact cratering

Adapted from Bagenal et al., 2004

Tidal Energy

Distance from Jupiter. Proportions are not kept

ganymede general information
Ganymede: General information
  • Diameter:

D(Gan) = 5262,4 km ~ 1.5D(Moon) ~ 1.08D(Mercury)

- the largest (not the heaviest!) satellite of Solar System;

  • Mass:

M(Gan) ~1.48*1023 kg ~ 2M(Moon)

  • Density:

ρ (Gan) ~ 1800-1900 kg/m3

  • Orbital parameters:

Orbital period: T(Gan) = 7.1546 T(Earth) ~ 7.1546 days

Semi-major axis: a = 1 070 412 km

Eccentricity: e = 0.0011 (range: 0.0009 ÷ 0.0022)

Inclination: i=0,204° (range: 0,05° ÷ 0.32°)

Image credit: NASA / JPL

Image credit: NASA / JPL

breakthrough missions having explored ganymede
Breakthrough missions having explored Ganymede

1977 – launch Voyager -1 and -2

1989-2003 – Galileo mission.

1996-1997 – the best observation of Ganymde

2006 – launch New Horizons. Now it is going to Pluto.

2007 - Ganymede flyby

slide7
Galileo mission (1989-2003)

Image credit: NASA / JPL

Date: 3 Aug 1989

Image credit: NASA / JPL

Date: 18 Oct 1989

slide8
Galileo mission (1989-2003)

Image credit: NASA / JPL

Date: 3 Aug 1989

Image credit: NASA / JPL

Date: 18 Oct 1989

slide9
Galileo mission (1989-2003)
  • Spacecraft instruments:
  • Solid State Imaging Camera (SSI)
  • Near Infrared Mapping Spectrometer (NIMS)
  • Photopolarimeter-Radiometer (PPR)
  • UltraViolet Spectrometer (UVS)
  • Magnetometer
  • Energetic particles detector
  • Plasma wave spectrometer
  • Dust detector
  • Heavy ion counter
  • Atmospheric probe:
  • Helium abundance detector
  • Atmospheric structure instrument
  • Neutral mass spectrometer
  • Nephelometer
  • Net flux radiometer
  • Lightning and radio emission detector

Galileo’s look at Ganymede (1996-1997)

the highest spatial resolution ( ~12 m/px);

the closest flyby ( ~264 km to surface)

slide10
Ganymede: previous results

Measurement types

Problem

  • Internal structure
  • Geology, surface morphology
  • Atmosphere, exosphere
  • Magnetosphere

Gravity field measurements (Galileo)

Surface features analysis(from images: Voyager, Galileo), mineral composition (from spectroscopy, Earth-based radar)

UV spectroscopic measurments, Voyager-1, HST, Galileo

Magnetic field measurements, energetic particles(Galileo), aurorae(HST)

slide11
1. Internal structure

Strongly differentiated internal structure:

1) Liquid core : Fe, (+FeS?), R~400-1300 km

2) Rock mantle(silicates, Mg-rich?)

3) Ice mantle (liquid-solid: high-pressure phase), 800-950 km

4) Ice crust (130-150km) (more lighter)

Ice phase state and lattice type are unknown…

1

2

3

4

rocks ~60%, ices~40% (if ρ~1,94 g/cm – Pioneer, Voyager)

Ice near its melting becomes a low-viscosity solid =>

=> Ice mantle convection like Earth rock mantle?

slide12
1. Internal structure

Crust deformations: tides

Callisto tidal flexing < Ganymede tidal flexing < Europe tidal flexing

Tides from interior model of Ganymede:

In the presence of a liquid ocean: tide can exceed 7 m peak-to-peak variation

Without an ocean: tidal amplitudes are less than 0.5 m

(Moore, 2003)

Mass anomalies

2 surface mass anomalies?

one a positive mass at high latitude and the other - a negative mass at low latitude.

No obvious geological features that can be identified with the anomalies. (Galileo data, Anderson 2004)

slide13
1. Internal structure

Open questions

Possible solutions and related payload

  • Interiors structure
  • Existence of liquid mantle
  • Origins of mass anomalies
  • Ice structure and form
  • Role of tidal heating at present
  • and in the past
  • Etc…

-Seismometer

-Thermal mapping

-Gravity field mesurements

-Librations measurements (e.g. by stellar sensor)

-Etc?…

slide14
2. Geology, surface morphology
  • Numerous traces of active geological processes in early history:
  • tectonism, volcanism (caldera-like features- Spaun,2001;
  • cryovolcanism–Schenk, 2001), etc…
  • Numerous impact craters
    • 2 different types of surface:

1 - Dark terrain ~ 1/3 of Ganymede

The oldest (~4Gy); heavily cratered; palimpsets;

Callisto-like

Galileo, 140m/px

2 - Bright terrain(2) ~ 2/3 of Ganymede

The youngest; less cratered; lanes through dark terrain

*both types may be reticulate

slide15
2. Geology, surface morphology
  • Numerous traces of active geological processes in early history:
  • tectonism, volcanism (caldera-like features- Spaun,2001;
  • cryovolcanism–Schenk, 2001), etc…
  • Numerous impact craters
    • 2 different types of surface:

DEM of topography (same scene)

Galileo, 140m/px

*both types may be reticulate

Schenk, 2001

global map based only on low resolution images
Global map based only on low resolution images

2. Geology, surface morphology

Galileo/Voyadger data

slide17
Morphology map based on Galileo mosaic

Geological units

Prockter, 1998

Prockter, 1998

slide18
2. Geology, surface morphology
  • Surficalrocks chemical composition
  • (telescopic observations; Galileo/NIMS spectroscopic data: T.McCord, 1998, etc)
  • - mainly H2O ice (50-90%)
  • presence of CO2 ice (Hibbits, 2003)
  • signs of SO2 , NH3
  • - hydrated minerals (MgSO4·nH2O, Na2Mg(SO4)2·4H2O , ...?
  • - still under studies
  • - unknown spectral features
  • *adsorb. bands 3.7, 3.88, 4.05, 4.25 µm, etc
  • - unknownmateral:
  • *darker and redder then water ice:
  • carbon-rich meteorite/mix of clays/organics component? tholin?
  • - still under studies…
slide19
2. Geology, surface morphology
  • Surficalrocks chemical composition
  • (telescopic observations; Galileo/NIMS spectroscopic data: T.McCord, 1998, etc)
  • - mainly H2O ice (50-90%)
  • presence of CO2 ice (Hibbits, 2003), O2
  • signs of SO2 , NH3
  • - hydrated minerals (MgSO4·nH2O, Na2Mg(SO4)2·4H2O , ...?
  • - still under studies
  • - unknown spectral features
  • *adsorb. bands 3.7, 3.88, 4.05, 4.25 µm, etc
  • - unknownmateral:
  • *darker and redder then water ice:
  • carbon-rich meteorite/mix of clays/organics component? tholin?
  • - still under studies…

NIMS/Galileo mapping

Carlson et al., 1996.

slide20
2. Geology, surface morphology

Surface temperature distribution (PPR/Galileo data)

Day side

Night side

Heat radiation ~ 60 µm

Tmin=80 K (observed)

Need for further studies of surficalthermophysical properties!

slide21
2. Geology, surface morphology

Possible solutions and

related payload

Open questions

  • Searching for specific substances:
  • -non-organic components:
  • sulfates, hydrated minerals
  • -organics: tholin, etc;
  • Altimetry and geologic mapping;
  • Thermal inertia data;
  • (Water) ice microstructure;
  • Geological processes: current and past
  • Confirmation of cryovolcanism hypotheses
  • Age of “dark” and “light” terrains
  • Vertical structure of crust beneath dark terrain
  • …. etc
  • Elemental analysis:
  • -Laser-stimulated emission UV spectroscopy
  • -Laser-stimulated mass spectroscopy
  • Analysis of species:
  • -IR imaging spectroscopy
  • -GCMS
  • -Raman spectroscopy
  • -DLS spectroscopy
  • Mineralogical & morphological analysis:
      • -Multispectral camera
  • -IR imaging spectroscopy
      • -Microscope
      • …etc?
slide22
3. Atmosphere. Exosphere

Ganymede does have atmosphere!

  • Very tenuous one: ~1016 cm-2
  • O, O2, H, H2, H2O, OH, … ?
  • sublimation and sputtering from icy surface ?
  • Frozen and trapped gases in the Ganymede surface?
  • -Micron-sized dust halo loosely bound by gravity – ice grains, the result of meteorite impacts
slide23
3. Atmosphere. Exosphere

Results of Dust detector/Galileo

Kruger, 2000

slide24
3. Atmosphere. Exosphere

Possible solutions and

related payload

Open questions

  • Abundance of volatiles, isotopes
  • Sources/sinks,
  • interactions with the surface and interiors
  • Exosphere, escape mechanisms
  • Photochemistry
  • Interactions with Jovian magnetosphere
  • Thermal and non-thermal heating, kinetics,
  • dynamics (tides?)
  • Dust particles acceleration and escape

Mass-spectrometry

Radio occultations between the orbiter and lander

Microwave sounding from the orbiter

IR heterodyne sounding from the orbiter or lander

ganymede s magnetic field internal induced magnetic fields
MGanymede’s magnetic field = internal +induced magnetic fields

Magnetic moment

M=1,3×1013 Т·м3~ three times greater than Mercury’s magnetic moment

The origin of internal m.f. is the dynamo mechanism dueto convection of core forming liquid materials in Ganymede’s core

(Fe- FeS )

Hauck et al., JGR, 2006

Ganymede’s magnetic field at equator ~ 720 nT

Jupiter’s magnetic field ~120 nT

Induced magnetic field ~ 60 nT

Region of unstably trapped plasma particles; convection region.

Kivelson et al., JGR, 1998

Induced magnetic field is due to time varying

component of the externally imposed Jupiter’s magnetic field. Source: electricalconductivity of aliquidwaterlayerbearingelectrolytessuchassaltsandacids.

Kivelson et al., Icarus, 2002

Ganymede is surrounded by a corona of hot oxygen atomes

Eviator et al., PSS, 2001

L~4-5 RG ~10000-13000 km

ganymede s interaction with the jupiterian magnetosphere
Ganymede’s interaction with the Jupiterian magnetosphere

4. Magnetosphere

Ganymede’s magnetosphere

From presentation by D.Titov

slide28
Interaction with Jupiter’s magnetic field

Open field lines are connected

to Jupiter’s polar magnetic field.

Field-aligned currents in Alfven wings ~ 1.2*106A

Jia et al., JGR, 2009

Z

X

Upstream

Reconnection line

Ionosphere

Downstream

reconnection line

Asymmetrical

Magnetopause

Ultraviolet auroral brightness (Eviator et al., 2001)

Regions of high-energy ions+electrons

E~100 keV

4. Magnetosphere

Alfven wings

Plasma flows.

Magnetsopheric convection.

No bow shock: velocity of magnetospheric flow is sub-sonic

Kivelson et al., 2001

Alfven wings

slide29
Amalthea

Amalthea

Io

Io

Europa

Europa

Ganymede

Ganymede

Charged particle flux and radiation dose equatorial profiles at Jupiter

Equatorial profiles of radiation doses under 0.27, 1, 2.2 and 5 g/cm2shielding, and separately dose under 2.2 g/cm2 from protons only near Jupiter.

Equatorial profiles of the integral fluxes of E > 0.5, >2 and >10 MeV electrons and

E> 2, >10 and >30 MeV protons at Jupiter.

open questions
Open questions:

4. Magnetosphere

  • Sources of internal and induced magnetic fields
  • Plasma convection and transfer in Ganymede’s magnetosphere
  • Structure of the ionospheric current system
  • Particle acceleration mechanisms
  • Dynamics of heavy ions in polar and equatorial regions; their rolein auroral brightness in Ganymede
  • Influence of Ganymede to Jupiter’s auroras
slide31
Conclusions
  • Ganymede is exceptionally challenging target
  • for Russian and international space exploration program
  • Lots of hot topics to remain hot for the next
  • 15(?) years
  • Strong, multidisciplinary community is
  • needed
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