Jupiter and Saturn; What we know, How we study them, and ......Jupiter & Saturn: What &...

Jupiter and Saturn; Jupiter and Saturn; What we know, How we study them,What we know, How we study them,

and What we and What we stillstill dondon’’t knowt know

Kunio M. Sayanagi (UCLA)

OutlineOutline

1. Giant Planets of our Solar System

2. Jupiter Mission Milestones

3. Cassini at Saturn

Solar System Overview

Vital StatsVital Stats

16h6min

17.143.88164.7930.44Neptune

17h14min

14.544.084.2320.08Uranus

95.18

317.94

1.00

Mass (Earth = 1)

10h14min

9h50min

24h

Rotation Period

1.001.001.0Earth

9.4529.469.54Saturn

11.2111.895.20Jupiter

Radius (Earth = 1)

Orbital Period (Earth-yr)

Distance from Sun

(AU)

Planet

SaturnSaturn’’s Love Handless Love Handles

Vertical Atmospheric StructureVertical Atmospheric Structure

Jupiter Saturn

Giant Planet Giant Planet JetstreamsJetstreams

Beebe. (2005) Fig. 1

Interior StructureInterior Structure

?

• Presence of Rocky Core- Unknown!- Hydrogen Eq. State

• Bulk Composition-- mostly Hydrogen and Helium-- Noble Gas Isotope abundance

will reveal formation history

Gas GiantsIce Giants

Magnetic Fields of Giant PlanetsMagnetic Fields of Giant Planets

?

• Jupiter and Saturn-- Generated in Metal-H Layer-- Strongly Dipolar

• Uranus and Neptune-- Generated in Water+Ice Layer-- Messy Field

How do we study Giant Planets?How do we study Giant Planets?

-- Observations (Earth and SpaceObservations (Earth and Space--Based Telescopes)Based Telescopes)

-- Space ProbesSpace Probes

-- Computer ModelingComputer Modeling

History of Jupiter ExplorationHistory of Jupiter Exploration

Hooke (1665)

Pioneer: ClosePioneer: Close--up Imagesup ImagesPioneer 10 Image of Jupiter in 1973

Voyager: WindsVoyager: WindsVoyager 1 Approach Movie (1979)

Ulysses: MagnetosphereUlysses: Magnetosphere

Galileo: HiGalileo: Hi--Res Wind FieldsRes Wind FieldsGalileo Wind Field Measurement of GRS (Choi et al. 2007)

Galileo: LightningGalileo: LightningGalileo Observation of Lightning Flashes (Little et al. 1999)

Cloud Composition & Vertical StructuresCloud Composition & Vertical StructuresGalileo NIMS Observation of Fresh Ammonia Ice Clouds (Baines et al. 2002)

AuroraAuroraGalileo Observation of Northern Aurora (Ingersoll et al. 1998)

Cassini: Stable Zonal JetsCassini: Stable Zonal Jets

Right:Red = Voyager in 1979 (Limaye, 1986), Black = Cassini in 2000 (Porco, et al. 2003)

Vertical Shear, Eddy Momentum FluxVertical Shear, Eddy Momentum Flux

Vertical Shear (Li et al. 2006)Eddy Momentum Flux (Salyk et al. 2007)

Vortex Life CycleVortex Life Cycle

(Li et al. 2004)

Oval BA Oval BA ““Red Spot Red Spot JrJr””

New HorizonsNew HorizonsNew Horizons Wind Field Measurement of Oval BA (Hueso et al. 2009)

Jupiter & Saturn: What & HowJupiter & Saturn: What & How

- Jupiter and Saturn have:- 3 kinds of clouds (H2O, NH3, NH4SH)- Banded Clouds Jetstreams- Jetstreams are very stable (and we don’t know why)- Long Lived Vortices- Aurora and Magnetospheric Dynamics

- How We Study:- Space Missions- Jets are measured by observing cloud motions- Cloud Composition = Spectroscopy

Near Future MissionsNear Future Missions

1. Juno

2. Europa Jupiter System Mission- Jupiter Europa Orbiter (NASA)- Jupiter Ganymede Orbiter (ESA)- Jupiter Magnetospheric Orbiter (JAXA)?

JunoJuno

- Polar Orbiter- Gravity Measurements to study Interior- IR+Microwave Radiometer to find Water

Limited Imaging Science Capability

View from Europa Jupiter Orbiter

Science Example I: Climate Database• Observing Jupiter from an Orbiter enables

measurements of:– Cloud changes (NH3 ice, H2O ice).– Thermal Structure/Changes.– Jetstreams.– Lightning.

• Constantly evolving dynamic atmosphere:

• Search for relationships between changes.

GRS 1992-1999

II: Waves, Periodicity & Coupling

Reuter et al., (2007)

Friedson et al., 1999Friedson et al., 1999

III: Polar Processes

• Aurora• High-Latitude Jets and Vortices

JupiterJupiter’’s Poles: Unexplored Frontiers Poles: Unexplored Frontier

North Pole South Pole

JupiterJupiter’’s Poles: Unexplored Frontiers Poles: Unexplored Frontier

North Pole South Pole

Sun et al. (unpublished ISS Data)

Polar Waves of JupiterPolar Waves of Jupiter

Polar Hood in UVVincent et al (2000)

Polar Wave in UV – Near IRBarrado-Izagirre (2008)

Polar HighPolar High--Altitude SpotsAltitude Spots

UV Dark Spothttp://photojournal.jpl.nasa.gov/catalog/PIA03473

Orton (personal communication)

Orton (personal communication)

Blue Circle = Persistent Auroral Zone

While Circle = 60degN

Polar TurbulencePolar Turbulence

Three Dynamic RegimesThree Dynamic Regimes

• Equatorial Jet

• Mid-Latitude Mixed Jets + Vortices

• Polar Turbulence

LowLow--lat Jets lat Jets Polar TurbulencePolar Turbulence

Low-Latitude Condition High-Latitude Condition

Sayanagi et al (2008)

- Jetstreams- Why are they stable?- What drives them?- How deep do they reach?

- Polar Turbulence- What process separates the Jets region and Polar

Turbulence?

- Waves- What excites the waves?

- Auroras - Effects on Atmosphere

UnknownsUnknowns

Take Home MessageTake Home Message- Jupiter and Saturn have:

- 3 kinds of clouds (H2O, NH3, NH4SH)- Banded Clouds Jets- Jets are measured thru moving Clouds- Long Lived Vortices- Aurora and Magnetospheric Dynamics

- Unknowns- Jets; Why Stable, How Deep, What drives them- Jets vs. Turbulence- Internal Structure (rocky core?)- Auroras’ effects

- History of Space Missions- Changes in Clouds and Winds Detected- Vertical Thermal and Dynamic Structure- Support Future Planetary Missions (please )