1. Voyages to Jupiter Galileo & Cassini

2. Galileo Mission

3. Galileo Spacecraft spins 3 rpm

6. 33 orbits and still going...

7. Jupiter is a giant ball of hydrogen gas Only outermost layers were probed Earth to scale

8. Probe Entered Downdraft Region Between Clouds

9. Probe Results Probe measured temperature, pressure, wind speed and chemical composition as it descended ~ 100km. Probe detected Only tenuous clouds Very dry air Strong winds >600 km/hr Chemical composition consistent with solar abundance + cometary material

10. White = ammonia clouds Orange = sulfur-colored ammonia Small scale turbulence generated by wind shears coalesce to form large scale vortices. Storms such as the Great Red Spot and white ovals last for decades to centuries.

11. Wind Shear and Eddies

12. Eddies Merging Feb. 1997 Sep. 1998 Two white ovals formed in 1930s Two Merged to one oval 60+ years later

13. Jupiter’s Ring Faint, tenuous rings of small particles chipped off small inner moons. Orbits shaped by satellites, evolve rapidly.

14. The Galilean Satellites

15. Galilean Satellite Geology

16. Zooming in on Callisto’s Craters

18. Chain of craters on Callisto Caused by broken up comets - such as Comet Shoemaker-Levy 9

19. Bright TerrainDark Terrain Fewer craters Younger Grooved & folded Many craters Older Ganymede’s Varied Geology

20. Grooves caused by expansion of Ganymede’s crust

21. Callisto and Ganymede - Heating of Ganymede led to separation of dense iron core, surrounded by rock with thick layer of ice on top. - Dark dust has accumulated on older surfaces of Callisto and Ganymede, burying small craters - Callisto suffered little heating and remains a mixture of ice and rock

22. Europa Dark Material Seeping Through Cracks

23. Ridges, Spots & Smooth Icy Plains

24. California Europa San Andreas Fault Astypalaea Linea

25. 50 km 10 km 5 km Zooming in on Cracks and Flows Ice - sometimes it suddenly cracks, sometimes it slowly flows

26. Europa’s young surface shows few craters Did this impactor crash right through the ice?

27. High resolution images show ice “rafts” - indication of thin ice crust, liquid ocean below?

28. San Fran Scale Comparison

29. The interior is mostly rock covered by a ~150 km layer of water A brittle crust (1-10km thick) has been disrupted in the past 10 million years by underlying fluid motions Does Europa have a liquid ocean? Could such ocean contain life? Or, is the water layer frozen, moving slowly, like a glacier? Europa

30. Freckles Competing Theories Upwelling Plumes Tidal Cracking

31. Io 3.57 g/cc Ganymede 1.94 g/cc Europa 2.97 g/cc Callisto 1.86 g/cc

32. Tidal Heating Laplace orbital Resonance Tidal forces increase strongly closer to Jupiter Heat the interior Remove water Drive volcanic activity

33. Io Amirani 300 km

34. Io’s Volcanoes & Geysers IR Pilan 5 months apart Prometheus Pilan Plume Pele

35. After quantities of lava are removed from below, the crust cracks and tilts, making tall, blocky mountains. Tvashtar Hiiaka Patera 50 km 11 km high

36. Io Mtns

37. Nightside of Io - Visible Glowing Lava Plume Gas & Dust + Airglow

38. Io Ganymede Europa Callisto 1 ton / sec Jupiter’s Giant Magnetosphere

41. Plasma Production at Io Schneider & Trauger Neutral Sodium Ionized Sulfur

42. Io Plasma Torus (Schneider & Trauger)

43. Cassini UltraViolet Imaging Spectrometer Larry Esposito, University of Colorado UV images of the toroidal cloud of ions at Io’s orbit, The S+ and O+ ions are trapped by Jupiter’s magnetic field. Jupiter is dark at UV wavelengths.

45. Jovian Aurora Radio to X-rays Power into polar atmosphere > solar flux (1) Main oval linked to middle magnetosphere (2) Polar storms (3) Satellite footprints

46. Aurora Io footprint Io wake Main Oval Polar storms Dusk Distortion? Clarke et al.

47. Cassini Spacecraft

48. Cassini flyby Dec. 2000 Galileo Orbiter 33 orbits Dec. 1995 to Oct. 2003 Voyagers Pioneers Ulysses Magnetopause

49. Cassini Flyby of Jupiter

50. 2004 Cassini Reaches Saturn

51. Galileo: The End Game Must never hit Earth or Europa 3 passes close to Io—to determine if Io has a magnetic field Hits Jupiter October 2003 100 Rjupiter Sun

52. SMEX mission Earth- orbiting UV telescope to observe Io, the torus and Jovian aurora

53. FAST/Polar goes to Jupiter RADIATION BELTS ~$350M space physics mission to explore polar latitudes Jupiter Polar Orbiter Particles & Fields Instruments

54. Let’s Keep Exploring!

55. Io Summary Tidal forces heat the interior, driving volcanism, resurfacing Io 100 times faster than Earth Silicate lavas erupt at temperatures >1800K Volcanic plumes feed a tenuous, patchy atmosphere of SO 2 - and S 2 and …? Complex interaction with Jupiter’s magnetosphere Escape of 1 ton/second of sulfur and oxygen ions 3 million Amps of electrical current connect Io and Jupiter Intense bursts of radio emission

56. HST Obervations of Io’s SO 2 Atmosphere Variable ….. with volcanic activity?

57. The Io Aurora Infrared Ultraviolet - energetic particles bombard atmosphere - ‘wake’ emission extends half way around Jupiter

58. John Clarke - HST Dave Young - Cassini Plasma Exp.