Voyages to Jupiter

Galileo & Cassini

Galileo Mission

Galileo Spacecraftspins 3 rpm

33 orbits and still going ...

Jupiter is a giant ball of hydrogen gas Only outermost layers were probedEarth to scale

Probe Entered Downdraft Region Between Clouds

Probe Results Probe measured temperature, pressure, wind speed and chemical composition as it descended ~ 100km. Probe detectedOnly tenuous cloudsVery dry airStrong winds >600 km/hr Chemical composition consistent with solar abundance + cometary material

White = ammonia cloudsOrange = sulfur-colored ammoniaSmall 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.

Wind Shear and Eddies

Eddies MergingFeb. 1997Sep. 1998Two white ovals formed in 1930sTwo Merged to one oval 60+ years later

Jupiters Ring Faint, tenuous rings of small particles chipped off small inner moons.

Orbits shaped by satellites, evolve rapidly.

The Galilean Satellites

Galilean Satellite Geology

Zooming in on Callistos Craters

Chain of craters on CallistoCaused by broken up comets - such as Comet Shoemaker-Levy 9

Bright TerrainDark TerrainFewer cratersYoungerGrooved & foldedMany cratersOlderGanymedes Varied Geology

Grooves caused by expansion of Ganymedes crust

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

EuropaDark Material Seeping Through Cracks

Ridges, Spots & Smooth Icy Plains

CaliforniaEuropaSan Andreas FaultAstypalaea Linea

50 km10 km5 kmZooming in on Cracks and FlowsIce - sometimes it suddenly cracks, sometimes it slowly flows

Europas young surface shows few cratersDid this impactor crash right through the ice?

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

San Fran Scale Comparison

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

FrecklesCompeting TheoriesUpwelling PlumesTidal Cracking

Io3.57 g/ccGanymede1.94 g/ccEuropa2.97 g/ccCallisto1.86 g/cc

Tidal HeatingLaplace orbital ResonanceTidal forces increase strongly closer to JupiterHeat the interiorRemove waterDrive volcanic activity

IoAmirani300 km

Ios Volcanoes& GeysersIRPilan 5 months apartPrometheusPilan PlumePele

After quantities of lava are removed from below, the crust cracks and tilts, making tall, blocky mountains.TvashtarHiiaka Patera50 km11 km high

Io Mtns

Nightside of Io - VisibleGlowing LavaPlume Gas & Dust + Airglow

IoGanymedeEuropaCallisto1 ton / secJupiters Giant Magnetosphere

Plasma Production at IoSchneider & TraugerNeutralSodiumIonizedSulfur

Io Plasma Torus (Schneider & Trauger)

Cassini UltraViolet Imaging SpectrometerLarry Esposito, University of ColoradoUV images of the toroidal cloud of ions at Ios orbit, The S+ and O+ ions are trapped by Jupiters magnetic field. Jupiter is dark at UV wavelengths.

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

AuroraIo footprintIo wakeMain OvalPolar stormsDusk Distortion?Clarke et al.

Cassini Spacecraft

Cassini flybyDec. 2000Galileo Orbiter33 orbitsDec. 1995 to Oct. 2003VoyagersPioneersUlyssesMagnetopause

Cassini Flyby of Jupiter

2004 Cassini Reaches Saturn

Galileo:The End Game Must never hit Earth or Europa

3 passes close to Ioto determine if Io has a magnetic field

Hits Jupiter October 2003100 RjupiterSun

SMEX mission

Earth-orbiting UV telescope to observe Io, the torus and Jovian aurora

FAST/Polar goes to JupiterRADIATION BELTS~$350M space physics mission to explore polar latitudes Jupiter Polar OrbiterParticles & Fields Instruments

Lets Keep Exploring!

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 SO2 - and S2 and ?

Complex interaction with Jupiters magnetosphereEscape of 1 ton/second of sulfur and oxygen ions3 million Amps of electrical current connect Io and JupiterIntense bursts of radio emission

HST Obervations of Ios SO2 AtmosphereVariable .. with volcanic activity?

The Io AuroraInfraredUltraviolet- energetic particles bombard atmosphere- wake emission extends half way around Jupiter

John Clarke - HSTDave Young- CassiniPlasma Exp.

IR, UV spot images

Text -> implications - energy does get to ionosphere- but not just at Io footprint