Lecture 33. Cassini-Huygens Mission.

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Lecture 33. Cassini-Huygens Mission.
reading Chapter 8
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Saturn
Pioneer 11 flyby in 1979 V1 in 1980 and V2 in
1981. Strong winds up to 1800 kph! Complex Rings
and Over 34 Moons. The Jewel of the Solar System
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Cassini-Huygens Mission
Took 7 years and 4 gravity assists (VVEJ) to get
there (in 2004). 4 year mission that includes 70
orbits around Saturn and its Moons.
Main goals -measure Saturns magnetosphere -up
close analysis of rings -composition and dynamics
of Saturns atm. -map surface of Titan -send
Huygens probe to surface of Titan Makes
measurements, data sent by high-gain antennae to
Earth, picked up by the Deep Space Network,
sending Gigabytes of data daily. Powered by 3
RTGs!
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Orbiter Instruments
Wide angle and narrow angle camera 10 Megapixel
CCD sees a quarter 4 km away. Cosmic Dust
Analyzer counts dust grains Ion and Natural Mass
Spectrometer studies positive ions and neutral
particles in upper atm. of Titan
and magnetosphere of Saturn Magnetospheric
Imaging Instrument first instrument to produce an
image of a magnetosphere and ionized gases
(plasma) Magnetometer Radio and Plasma Wave
Science Instrument measures radio signals from
Saturn, from interaction of solar wind
with Saturn and Titan RADAR uses microwaves to
image Titan Radio what is this used for??
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Visible and Infrared Mapping Spectrometer
Spectrometer splits light into its component
wavelengths, fingerprint of compounds
present. Mapping component makes a map of where
the different compounds are present.
bright features thought the be a volcano
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Infrared Spectrometer
Measures amount of heat coming from a
surface. Cracks of Enceladus 91K
(-296C) Evaporation of warm ice may produce
the plume seen. Fractures bluer because
they have larger ice crystals
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5 different terrains bright, reflective
surface Parts have no craters gt35 km Others
have no craters Fissures Plains Corrugated
terrain Crustal deformations Interior may be
liquid Dont know what the source of heat
is! May be tidal heating from orbital
perturbations with Saturn, Tethys and Dione.
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Ultraviolet Imaging Spectrograph
Box of 4 telescopes that can see uv light. Image
object, render it in false colors. Shows more
ice in the outer part of the rings. Red dirtier
ice, perhaps smaller particles. Found
battleship-sized clumps of particles in the
rings. Come together and disperse on a daily
basis. Can detect H, O, CH4, water, acetylene,
ethane. Collect data as Sun or other stars pass
behind Titan. Provides information on
composition, temperature, structure of the
atmosphere.
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Huygens Probe
Named after Christiaan Huygens who discovered
Titan in 1655. Built and designed by ESA. On Dec.
2004 released from Cassini. 20-day approach
toward Titan. Descent slowed by three parachutes,
took 2 hours 27 min. Collected data on
composition of atmosphere clouds. Landed near
the equator. Survived 1 hr 12 min after landing
on the frozen surface.
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Huygens Probe Instruments
Atmospheric Structure Instrument measures
physical properties of the atm, density, wind
gusts, waves (if probe landed in an ocean),
conductivity of surface Doppler Wind
Experiment wind speed during descent Descent
Imager/Spectral Radiometer Measures upward and
downward flow of light Aerosol Collector and
Pyrolyser and GCMS heated aerosols and sent to
GCMS, GCMS measured composition of atm. Surface
Science Package several sensors to measure
physical properties, speed of sound,
accelerometer (hard or soft surface), tilt meter
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Huygens - General Surface Features
Obtained clear images 40 km above the
surface. Resembles Earth - structure of the
atm. - meteorology - land forms - fluvial
(river) activity Strong evidence for erosion due
to liquid flows (possibly methane). Boundary
between bright, icy, rugged terrain. and a darker
flat area. Dark and bright areas correspond to
observations made on the orbiter. Bright areas
are higher in elevation. Dark areas appear to
drain the light areas into a low-lying
dark floodplain. Interpreted as coastline with
bright islands. Probe landed on dark area.
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Huygens - Surface
Spectra of landing site composed of dirty
water ice. Water ice pebbles 3mm-15 cm across.
Water ice rocks coated in hydrocarbons. Landed
on a solid surface, puff of evaporated methane
detected after impact with the warm probe. Also
detected from the surface compounds not found
in the atm C6H6, C2N2, CO2 Suggests complex
chemistry occurring on the surface, and
different from the atm. Surface wet with
methane. Penetrometer surface consistency of
loose wet sand
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Huygens - Atmosphere
Landing site 93.7K, 1.47 bars Winds at 120 km
were 450 kph Winds at 100-60 km had a high
wind-shear Haze detected all the way down to the
surface. Methane at the surface 5 Relative
humidity of methane is 50. So, unlikely to get
methane fogs. Major questions What is the
source of methane? Methane is continually
destroyed by photochemical reactions. Where are
all the pools of hydrocarbons if photochemistry
has been going on for 4.5 Ga?
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Huygens - Chemistry
Complex organic chemistry confirmed - no new
organic compounds found in the atmosphere. May
be unidentified organic compounds on the
surface. 40Ar found in the atmosphere - suggests
active internal geology
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Life on Titan?
Do you have the 5 thing needed to have life?
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Properties of Water that are Important for Life
It is the universal solvent because it can
dissolve the most substances than any other
liquid. Electrical charge differential helps it
dissolve ions, like sodium chloride. Water
molecules are attracted to each other - creates
surface tension Water forms drops, capillary
action allows water to be sucked up plant roots
and blood vessels Water is a polar compound. Ions
are needed for life!
Water can also dissolve uncharged
organic compounds, like sugars. It is found in
all three states solid, liquid, gas on the Earth
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Methane and Ethane Liquids
Are hydrocarbons - so have a greasy nature. Are
non-polar compounds so they -dont dissolve
ions. -dont have much surface tension.
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Lecture 34. Extrasolar Planets.
reading Chapter 9