Life Giant Planets Moons

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Life on Giant Planets

Stephen Eikenberry

28 October 2010

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The Jovian Planetsmuch larger than terrestrial planets

not solid - gaseous

Jupiter

Jupiter, Saturn, Uranus, Neptune

all have many moons


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Jupiter

Named after the mostpowerful Roman god

t r - r g test o ect n t e

night sky (after the Moon and

Venus)

Atmospheric bands are very

different than inner planets

called Galilean Moons


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Saturn

Named after the father of Jupiter in Greco-Roman mythology

Similar banded atmosphere Uniform butterscotch hue

any moons

Spectacularring system


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Uranus

Discovered by William

Hersc e n 1781

Named after father of Saturn

Barel visible to naked e e

Featureless atmosphere

Deviations in the expected

possibility of another planet

influencing its motion


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Neptune

There had to be anotherplanetinfluencing Uranus

1845 - John Adams determined the planets mass and orbit

10 months later - Urbain Leverrier inde endentl came u with the

same result 1846 - Johann Galle found the new planet Neptune

Bluish Jupiter atmosphere


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Space Craft Exploration of Jovian Planets

Voyager1and 2 left Earth in 1977

reached Jupiter in March and July of 1979

Used Jupiters strong gravity to send them on to Saturn -gravity assistgravity assist

oyager use aturn s grav ty to prope t to ranus an t en on to eptune

Studied planetary magnetic fields and analyzed multi-wavelength radiation Both are now headed out into interstellar space!


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Space Craft Exploration of Jovian Planets

Galileo - launched in 1989 and reached Jupiter in December 1995

Gravity assists from Venus and Earth

Two components: atmospheric probe and orbiter

Probe descended into Jupiters atmosphere

Orbiter went throu h moon s stem

Cass n m ss on to Saturn

Studying Saturns moon

Titan in much the same wa

as Galileo studied Jupiter


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Jovian Planet Properties

Most of their mass is Hydrogen and Helium light elements = low densities

High surface gravity allows their atmospheres to retain these light elements

Dense compact core at the center

But, NO SOLID SURFACE gaseous atmosphere becomes denser (eventually

liquid) at core

Differential Rotation outer regions rotate slower than inner regions


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Jovian planets - axis tilt and magnetic fields

Uranus has the most inclined rotational axis - extreme

seasons!All appear to have strong magnetic fields - rapid rotation and


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Jupiters Atmosphere

Great Red Spot

molecular hydrogen 86%

helium 14% small amounts of methane, ammonia, and water vapor

Darker colored belts lie atop downward moving

convective cells

Lighter zones are above upward moving cells

Belts are low-pressure, Zones are high pressure

As on Earth, wind moves from high to low

East/West along equator

Temperature difference between bands is main

reason for color difference


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Jupiters Atmospheretroposphere

Thin layer of white ammonia clouds

125 150 K

Colored clouds below that Warmer - 200 K

clouds are mostly droplets or

crystals of ammonium hydrosulfide At dee er levels clouds of water

ice or water vapor

The Galileoprobe survived for

about an hour before being crushed

a s a u e.


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Weather on Jupiter

Main weather feature Great Red Spot!

swirling hurricane winds

as as e over years

diameter twice that of Earth rotates with planets interior

powered by the zonal flow

Smaller storms look like white ovals (this one is over 40 years old)

Why do the storms last so long?

On Earth, hurricanes lose power when then come upon land

o cont nents on up ter not ng to stop t em once t ey start


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Saturns Atmosphere

molecular hydrogen 92.4%

helium 7.4%

traces of methane and ammonia

Layer of haze

roposp ere con a ns c ou ayers

ammonia ice

ammonium hydrosulfide ice

Overall temperature is cooler than

Ju iter

water ice

Atmosphere thickness is 3 times that

of Jupiter (caused by lower surface

Thicker clouds result in less variedvisible colors


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ea er on a urn

Computer enhanced image shows bands, oval storm systems, and

turbulent flow patterns like those seen on Jupiter


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Atmospheres of Uranus and Neptune

helium 14%

methane 2% (Uranus) 3% (Neptune)

Abundance of methane ives these lanets their blue colorMethane absorbs longer wavelength light (red) and reflects short

wavelength light (blue)


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Weather on Uranus and Neptune

UranusFew clouds in the cold upper atmosphere featureless

Upper layer of haze blocks out the lower, warmer clouds

NeptuneUpper atmosphere is slightly warmer

than Uranus (despite its further distance

from Sun)More visible features (thinner haze, less

dense clouds lie higher)

Storms Great Dark Spot


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Internal Structures models that fit the data

e a c y rogen s e qu me a

Jupiter SaturnUranus/Neptune

Increasing temperature and pressure deeper in core

Jupiter bulges at radius (7% larger)

Saturn less assymetric larger core same basic overall structureon a smaller scale

Uranus/Ne tune have a hi h densit slush below cloud level -

compressed water clouds


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Primordial Heat

-Jupiters heat source results fromstrong heating during formation by the

Generation of Heat

co apse o ma er a on o e core

-Saturn generates some eat ue to t e

gravitational contraction of helium gas

Effect of internal heating - raises the temperature of theinterior and atmosphere to higher values than expected

from the Suns heatin alone


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We see lots of life chemicals! (Water, methane, etc.)

Lightning observed too

Similar to early Earth atmosphere (?)

Ex ect com lex h drocarbons Ure -Miller ?

At some depth, have warm temps (~300K)

Methane is not a sign of life here just a sign of LOTS

of free hydrogen, some carbon, relatively little oxygen

No solid surface no oceans, no tidal pools, no claymatrix in short, no (Earth-like) places for life formation


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What about gas matrix life? (i.e. no solid surface, but life in

the air)

Wind s eed turbulence roblem tr to ut to ether a house

of cards outdoors in a hurricane

Thats easier than forming life in Jupiters atmosphere!

Convection

Causes any chemicals from warm lower layers to rise

This gives exposure to solar UV radiation, which breaksit down


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Does this mean NO life here?

Nope

Floater possibility

,


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Moons

Almost all moons inthe Solar S stem orbit

the J ovian planets J u iters 4 maor

moons are theGalilean satellites: Io,

, ,Ganymede

smaller moons


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Io

Innermost Galileansatellite

Reddish color

moo youngsurface

x reme vo cancactivity

n eror a y ea eby J upiter (& Europa)


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Io Tidal Heating


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Europa econ a ean

satellite

s , g y-

reflective color

moo sur ace wpatterns similar to ice

caps on Earth

Young surface

y uwaterworld with icecrust


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Life on Europa?

Possible view of Europan

ocean


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Life on Europa?

Europa seabed may resemble black smoker environment on

Earth (!)

Probabl little O in the water where would it come from?

But anaerobic bacteria are the basis for life in Earth vents (even iflarger life O2-dependent)

exploration mission


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Callisto & Ganymede

Rock/ice moons

v ence or some

glacial flows


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Saturns Titan

Largest moon

moot sur ace ue

to thick atmosphere (!)

n rare mages s owevidence for

continents beneath


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Titans Surface

Lakes of liquid hydrocarbon imaged from orbit via Cassini; T~85K (probably ethane/methane)

Huygens lander mission in 2006


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Titans Surface

Huygens lander mission in 2006


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Life on Titan?

Solid/liquid phase environment similar to Earths surface

Totally different chemicals and temp ranges; will not be H2O-

based like on Earth But still a possibility


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Neptunes Triton

Largest Neptunianmoon

Retrograde orbit

r a - egrees

Could indicate KBOorgn ??


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Other moons


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Enceladus

Saturn moon

ater ere too


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Enceladus

Saturn moon

ater ere too


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Summary The Giant Planets lack solid surfaces and have

extreme wind speed, turbulence and convection

Still .. we cannot rule out l ife there (floaters?) Moons such as Europa and Enceladus may have

liquid water oceans with Earth-like temperaturesand geothermal vents; these may be promising

places to search for life The moon Titan has a thick atmosphere and

(apparently) lakes/rivers of liquid hydrocarbons;tem s are COLD but we can ima ine some low-

temperature, slow-reaction life developing heretoo (?)

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