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Saturn

• Moons
• - Titan
• - Three sizes of moons
• Exploration
• - Cassini

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Saturns Satellites

• 1. Planet sized Titan
• Intermediate in size between Mercury and Mars
• Orbits 1 million km from Saturn
• Diameter 5150 km density 1880 kg/m3

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Saturns Satellites
2. Six moderately-sized satellites - Very low
densities (1700 kg/m3) probably mostly ice - All
synchronously orbit in the Saturns equatorial
plane
Rhea
Iapetus
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Saturns Satellites

• 3. 30 Tiny Satellites
• Some might be captured asteroids or other space
  debris/rocks
• (outermost satellites Phoebe orbits at 12
  million km, retrograde orbit
• Hyperion orbits at 3.5 million km and isnt
  spherical 410 x 260 x 220 km)
• Some might be jagged remnants of collisions
  between rings, satellites help to confine or
  spread out ring material
• (innermost satellites Prometheus and Pandora
  shepherd satellites
• and Pan orbiting in the Encke gap)

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• size 5150 km
• - smaller than Ganymede (5268 km)
• - larger than our moon (3476 km)
• density 1800 kg/m3 (low density)
• must be made of ice and rocks
• 1665 discovered Huygens
• 1944 methane detected in spectrum of
• atmosphere
• only satellite known with an atmosphere
• cool enough and massive enough to
• retain heavy atmospheric gases

Titan
Voyager image of Titan
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• Composition of Titans atmosphere
• more gas (by mass) than Earths atmosphere
  (thicker)
• 90 of atmosphere is NITROGEN
• - N2 came from ammonia (NH3) common in outer
  SS
• second most abundant component is METHANE
  (natural gas)
• - when UV methane ? hydrocarbons (e.g.,
  ethane)
• - ethane condenses and rains down on Titans
  surface
• Titan may have liquid reservoirs of hydrocarbons
  on surface

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• IR wavelengths can penetrate through Titans
  atmosphere
• map of reflectivity of IR
• The dark patches have lower IR reflectivity
  which could be liquid hydrocarbon seas or large
  expanses of solid organic material.
• The bright yellow could be highly
  reflectivecontinents.
• hydrocarbons similar to life building blocks on
  Earth
• TOO COLD on Titan -288 F!

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Saturns mid-sized satellites come in three
sizes - pairs of each Iapetus and Rhea
largest Dione and Tethys midsized Mimas and
Enceladus smallest
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Mimas
The smallest of the six has an enormous impact
crater among many other craters.
Cartoon of what Saturn might look like from Mimas
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Enceladus
Few craters and many ice flows on its young
surface suggests internal tidal heating from
Dione and Saturn
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Enceladus
Mostly heavily cratered with a curious, smooth
plains region of solidified water and ammonia
lava.
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Dione
Dione has a heavily cratered leading side and a
smooth trailing side.
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Rhea
Also has a heavily cratered leading side and a
smoother trailing side.
cartoon of surface of Rhea
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Iapetus
Also has a heavily cratered leading side which is
abnormally dark and a smoother and brighter
trailing side.
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A Saturn-orbiting spacecraft, CASSINI, and a
Titan lander, HUYGENS, will provide a wealth of
new information.

• Arrived in 2004, the enormous Cassini spacecraft
  will spend four years orbiting Saturn and
  studying the planet, rings, and moons.
• The Huygens Probe detached and parachuted into
  Titans atmosphere. It sent back detailed
  information before it crashed into the surface.

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Cassini Spacecraft
Radio Plasma Wave Subsystem Antenna (University
of Iowa)
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• Cassini science discoveries
• 2000 Cassini flew by Jupiter
• Image shows Jupiters magneto-
• sphere radio emission from
• charged particles spiraling around
• magnetic field lines!

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CD on board Cassini with 600,000 scanned
signatures
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Cassinis trajectory en route to Saturn and
Titan
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