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Martian Canali
Viking Lander
Labeled release experiment (LR)
Moistened soil sample with a liquid nutrient
medium that contained carbon-14.
Container monitored to see if carbon-14
released into air.
Control samples
Martian soil samples were heated to 160 C, a
temperature that destroyed all biological
activity in terrestrial soils before testing, and
then tested with the same three
experiments.
Life on Mars?
Molecular analysis Experiment
Heated soil to look for organic molecules.
Found a complete absence of any organic
molecules in the Martian soil.
The Conclusion
The Martian surface is completely devoid of
life.
Gas release was due entirely to chemistry.
High concentrations of chemicals such as
hydrogen peroxide and strong ultraviolet
radiation combine to make the surface of
Mars completely sterile.
Inconclusive?
These three experiments have been shown
since the seventies to miss life present in arid
regions on Earth.
Assumed, incorrectly, that all life got energy
either from photosynthesis or by eating
organic compounds.
Fossilized bacteria?
Beagle 2
Landed on Mars Christmas day 2003
Contained a mass spectrometer 100 times
more sensitive than Vikings’ to look for
organic molecules and peroxides in soil
Test for carbon-12 to carbon-13 ratio
Mars Rover
Grey Hematite
Opportunity landing site
Curiosity
Gale crater Curiosity landing site
Gale Crater
The Face on Mars
Exam 2 Tuesday
Covers Chapters 7-10, & 14
One sheet of notes with writing on one side only
Jovian Planets
Discussion
Why do you think it is that of the Jovian
planets we know the most about Jupiter?
Discussion
Jupiter is 71% hydrogen, 24% helium, and 5%
heavier elements. How can we figure out the
composition of Jupiter?
Discussion
Jupiter has more heavy elements than the Sun
does. If both formed from the same nebula,
why do you think that is?
Jupiter: 71% hydrogen, 24% helium, 5% heavier elements
Sun: 73.4% hydrogen, 25% helium, 1.6% heaver elements
Discussion
Jupiter is 3 times as massive as Saturn, yet is
only 1.2 times bigger. Why do you think that
is?
Mass-radius relation
Discussion
All the Jovian planets are covered with thick
clouds. How do you know anything at all
about the interior of the Jovian planets if we
cannot obverse them?
Clues to internal structure
1. Mean density
2. Gravitational mapping
3. Shape of the planet
Mean density of planets
Earth
Mercury
Venus
Mars
Moon
5.5 g/cm3
5.4 g/cm3
5.2 g/cm3
3.9 g/cm3
3.4 g/cm3
Neptune
Sun
Jupiter
Uranus
Saturn
1.6 g/cm3
1.4 g/cm3
1.3 g/cm3
1.3 g/cm3
0.7 g/cm3
Rotation
The Jovian planets tend to spin very fast
Jupiter – 9 h 55 m 29 s
Saturn – 10 h 39 m 25 s
Uranus – 17 h 14 m 24 s
Neptune – 16 h 6 m 36 s
Discussion
What happens as the rotation rate of a planet
is increased?
Oblateness
Jupiter’s oblateness
Equatorial radius: 71,492 km
Polar radius: 66,854 km or 6.5% smaller.
Oblateness 6.5
Discussion
How does the oblateness of a planet
depend on the rotation rate, the size, and
the mass of a planet?
Discussion
Saturn’s diameter at its equator is 10% larger
than its pole to pole diameter.
Saturn is smaller than Jupiter and rotates more
slowly. How come its equatorial bulge is bigger?
Saturn’s internal structure
For Saturn’s size and density, it is not oblate
enough to have the same internal structure as
Jupiter.
Saturn has a larger rocky core, comprising about
10% of its total mass (about 9.5 Earth masses).
Discussion
Why is Saturn’s liquid metallic hydrogen layer so
much smaller than Jupiter’s?
Discussion
The equators rotate faster than the poles. The
poles on Jupiter take and extra 5 minutes to
complete a rotation.
With differential rotation and a big liquid
metallic interior, what do you expect to be the
result?
Jupiter’s magnetic field
Discussion
If Jupiter and Saturn rotate differentially, how
do we decide what their rotation rates are?
Discussion
Saturn’s magnetosphere is not as big as
Jupiter’s, between 10 to 20 % that of
Jupiter. Why not?
Discussion
Unlike the terrestrial planets that receive
most of their energy from the Sun, the planet
Jupiter emits about twice as much energy as
it receives from the Sun. Where do you think
this energy comes from?
Jupiter as a failed star
Core at a pressure of 70 million atm
Temperature 22,000 K
Jupiter would need 80 times its current mass to
start hydrogen fusion in its core.
Jupiter’s atmosphere
Hydrogen
Helium
Water
Methane
Ammonia
86.4%
13.6%
0.1%
0.21%
0.07%
Discussion
Jupiter, like the Earth has a stratosphere.
Why do you think that is?
Cloud bands
Why do you think Jupiter has cloud bands?
Discussion
The boundaries between the zones and belts
on Jupiter mark a change in wind direction
with typical speeds of 500 km/hr. What
causes these strong eastward and westward
winds on Jupiter?
Jupiter in the IR and visible
Discussion
What does the infrared picture of the bands
tell you about the difference between the
belts and zones of Jupiter?