Transcript Planetary Exploration

Planetary Exploration
Travel to exotic locations
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• Jupiter’s four
“Galilean” moons
• Similar size to our
moon
• Visible with
binoculars:
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Io: Innermost large moon
• Similar in size to the Moon.
• Intensely volcanically active!
(40 times as active as Earth)
• Hundreds of active volcanos,
plumes hundreds of miles high
• Why?
• This was unexpected.
– Scientists expected to see something
like our moon
– Io is too small for internal heat and
too far from the sun for solar heat
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Io Glowing in the Dark...
• Galileo images
show glowing
gases, hot
volcanos, in
Jupiter’s shadow
• Volcanic glow
suggests
volcanos are too
hot to be
“ordinary”
basalt magma
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Tidal Heating of Io
• Where does the
energy come from?
• Tides distort Io when
closer to Jupiter:
surface moves 100
meters every day
• Continually
changing shape heats
interior
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Eruptions
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1979
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1996
Learning about the volcanos
• What kind of volcanos
are they?
• How hot are they?
• What are they made
of?
• What can they tell us
about volcanos on
Earth?
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Links to the Earth
• There have
been huge
eruptions on
Earth that have
never been
seen by
humans, but
similar events
are frequent on
Io.
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Zooming in on Jupiter and Io
Jupiter and its moons from a backyard telescope
(1,000,000 miles across)
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Zooming in on Jupiter and
Io
• Best view of
Jupiter from
an Earthbased
telescope
• (100,000 miles
across)
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Zooming in on Jupiter and Io
• Jupiter
and Io
from
Hubble
• (60,000
miles
across)
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Zooming in on Jupiter and Io
• Io against Jupiter,
from Galileo
• (2200 miles across)
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Zooming in on Jupiter and Io
•Io volcanos
Prometheus and
Culann
•(450 miles across)
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Zooming in on Jupiter and Io
• Prometheus lava
flow, Io
• (50 miles across)
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Zooming in on Jupiter and Io
• Edge of Prometheus
lava flow, Io
• (6 miles across)
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Tvashtar, November 1999
Fire Fountains seen by Galileo SSI
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From Hawaii
•
• And again
by Galileo
SSI in
February,
2000
Also seen from the ground
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What we’ve learned
• Volcanos are hotter than Earth’s volcanos (up to 2700 F
vs. 2100 F): like volcanos early in Earth’s history
• Eruptions much like terrestrial ones (but bigger): fire
fountains, lava flows, lava lakes
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Europa: Abode of life?
• Little known
before
Galileo...
• Icy, fractured,
surface
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Zooming in on Europa:
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100 x 140 km
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32 x 42 km
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1.7 x 4 km
• Eroded appearance at highest resolution
• Few impact craters
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• Surface layer has fractured and separated: floating on
ocean, or slush?
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• Craters subdued, rare: young(?), soft surface
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Ocean on Europa?
• Jury is still out – but many scientists agree
• Galileo data shows evidence for thin rigid crust
over soft interior, but can’t tell if interior is liquid,
or slushy ice
• Surface is probably very young, currently active,
but possibly as old as 1 b.y., which would
probably rule out ocean
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Comparative planetology
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Surface Processes
• Io
– Volcanism (endogenic)
– No craters (young surface)
• Europa
– Tectonics (endogenic)
– Cryovolcanism (endogenic)
– Few craters (young surface)
• Ganymede
– Tectonics (endogenic)
– Some craters (older surface)
• Callisto
– Mostly Craters (very old surface)
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