1
Amazing Saturn

Saturn from the ground
2
Saturn Information Overload

The Cassini Mission started orbiting Saturn in 2004.
3
Getting There

Planetary pinball with passes by
Venus, Venus, Earth, and Jupiter
to pick up speed.
4
Saturn Information Overload

The orbiter includes imaging, radar, particle and field
experiments and a probe that was dropped onto Saturn's largest
moon, Titan.
5
Saturn Information Overload

Orbit after orbit its has provided a firehose of information about
Saturn, its rings, and its Moons.
6
7
8
9
Infrared image
showing that
Saturn, like Jupiter
radiates internal
energy in excess of
the Sun's input.
It should have
cooled off by now
however.
It is likely that
differentiation of
helium toward the
center of Saturn is
generating
mechanical energy.
10
11
12
13
14
Saturn's Rings



Saturn's rings consist of a myriad of particles of relatively pure
water ice with sizes ranging from from snowflakes to mountains
(and moons).
All combined the material amounts to no more than a tiny
moon's worth of ice.
The rings likely originated via the disruption (via impact?) of a
small icy satellite.
15
The Roche Limit and Planetary Rings
16
Substructure in Saturn's Rings
Mimas
Consistent tugs from
satellites clear out gaps.
Mimas maintains the Cassini
Division (the most apparent
large gap).
A particle in the Cassini
Division orbits Saturn twice
for every one orbit of Mimas.
17
Mimas
18
Satellites can directly
create gaps and shape
rings as well.
19
20

Tenuous outer rings formed by erosion and, in the case of
Enceladus, cryovolcanic activity.
21
22
Erosion of Phoebe by impacts generates (temporary) ring particles that strike
and modify Iapetus.

These particles are evident via their mid-infrared blackbody glow,
despite being only 90K (-300F)
23
24
25
26
Big Icy Satellites
Dione
Rhea
27
Big Icy Satellites
Tethys
28
Equatorial Ridge
Voyager Mountains
Iapetus
29
30
31
32
Hyperion
Dozens of Small Icy
Satellites
Janus
Epimetheus
Telesto
33
Hyperion
34
Phoebe
Orbits Saturn
backwards
Source of its
own diffuse ring
Is it a captured
“comet”/Kuiper Belt
Object?
35
Enceladus
An inner moon of
Saturn.
The most reflective
object in the solar
system.
Brighter than snow!
Both “young” and “old”
terrain
36
Enceladus!
http://www.planetary.org/blog/
37
http://www.planetary.org/blog/
38
http://www.planetary.org/blog/
39
The Plumes of Enceladus


Water vapor and ice particles launched at
speeds high enough to escape.
Liquid water inside Enceladus??

Tidal heating (a little)

Radioactive heating (maybe)

Water-ammonia mixture (possible)
40
A World Too Small for Volcanism?
41
Enceladus to Scale
Enceladus
42
The south pole
cracks, which are
the source of the
jets, are warmer
than their
surroundings.
The boxes give
temperature in
Kelvins – so about 300F.
43
Warm Eruption Sites
44
A Potential (unexpected)
Habitat
45
Titan

Titan is the second largest moon in the Solar System and bigger
than the planet Mercury.
46
A Chemistry Laboratory

Titan has a thick, primarily
nitrogen, atmosphere with a
surface pressure 1.5 times that of
Earth.
 The
atmosphere contains traces of
methane and ethane as well as other
organic molecules.
 Ultraviolet
sunlight breaks these
molecules apart and they reassemble
into even more complex molecules.

 Larger
The atmosphere is filled with
organic particle smog that
hides the surface at visible
wavelengths
molecules and particles filter
down and collect on the moon's surface.
47
A Thick Smoggy Nitrogen Atmosphere
48
Peering through the Smog at Titan

Small particles block short wavelength light but permit longer
wavelengths to pass.
 Sunsets
are red for this reason. Red light penetrates the atmosphere better
than blue.
Visible
Infrared
49

A relatively crater free
surface
 resurfaced
by weather and
cryovolcanism.
50
51
Clouds and (methane) Rain on Titan
52
Springtime Weather on Titan
53
Lakes and Erosion on Titan
54
Lakes and Erosion on Titan
55
Lakes and Erosion on Titan
56
Lakes and Erosion on Titan
57
58
Visiting Titan's Surface –
The Huygens Probe
59
Visiting Titan's Surface –
The Huygens Probe
60
Visiting Titan's Surface –
The Huygens Probe
61
Visiting Titan's Surface –
The Huygens Probe
62
Visiting Titan's Surface –
The Huygens Probe
63
64
65
The Surface of Titan
66
Atmospheric
Composition
67
Things to Know About Saturn


Saturn has the same types of clouds as on Jupiter but lower in
the atmosphere (thus harder to see).
Saturn's rings are made of nearly pure water ice chunks
 kept
apart by Saturn's gravity (Roche Limit)
 gaps

cleared by tugs from Moons
Titan is the 2nd largest moon in the Solar System
 It
has a thick nitrogen atmosphere
 Methane/ethane

are trace gasses that forms clouds and produce rain.
The surface is eroded by the “weather”
 Solar
ultraviolet radiation forms an organic smog, coating the surface with
pre-biotic chemical compounds.

Enceladus, a tiny moon, has water geysers that spray material
out to form Saturn's E-ring.

Subsurface water means prospects for life!