Titan’s Lakes and Seas Jonathan I. Lunine Cornell University
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Transcript of Titan’s Lakes and Seas Jonathan I. Lunine Cornell University
Titan’s Lakes and Seas
Jonathan I. LunineCornell University
Outline
1. Occurrence and distribution2. Composition3. Longevity4. Astrobiology5. The future
Outline
1. Occurrence and distribution2. Composition3. Longevity4. Astrobiology5. The future
Ideas about surface methane and ethane on Titan were stimulated by Voyager 1 in 1980. Cassini discovered lakes and seas on Titan in 2006.
Aharonson et al., 2009
The lakes and seas are for the most part confined to high latitudes
The lakes and seas are part of Titan’s methane cycle.
Titan hydrocarbon reserves (surface-atmosphere)
1,000 gigatons is the estimated amount of oil, coal and gas energy companies have in reserve on Earth
Lorenz et al. 2008
Mike Carroll
The seas are the third of three known carbon reservoirs
Outline
1. Occurrence and distribution2. Composition3. Longevity4. Astrobiology5. The future
ethane in Ontario Lacus (Brown et al. 2008)
We do not know the bulk ethane/methane/propane abundance
in the seas
Theoretical calculationCordier et al 2011
Outline
1. Occurrence and distribution2. Composition3. Longevity4. Astrobiology5. The future
Seasonal:Lora et al., 2011
Orbit precession
Aharonson et al
Sunlight received at thesurface.
Prime EquinoxSolstice
Turtle et al. 2011: shrinkage of Ontario Lacus over the late southern summer is consistent with evaporation
Seasonal effects are evident in the south but not the north.
Ligeia Mare may be part of a crustal liquid system that has persisted for some time, but not geologic time. Why are their seas today, and what is
their relation to the evolution of the interior?
100 km
Metallic Core
Salt-Rich OceanHP-Ice Layer
Ice/Hydrateshot
water
moves
through
hydrated
silicates
to oceanActively dehydrating rock core raises heat flux by 25-100%
The ethane sinks in the crust...into the ocean?
Density versus temperature of clathrate
Outline
1. Occurrence and distribution2. Composition3. Longevity4. Astrobiology5. The future
Chemical evolution on the road toward life would be a profound
scientific discovery
-CN
catalyst
HCN (produced in Titan’s high atmosphere)
Ligeia Mare’s equivalent of the chains from which proteins are built?
Simulation of HCN polymer (blue) seen against background of abiotic chemistry. Flight qualified mass specs can see this and other polymers indicative of chemical evolution on the way to life.
yielding
Outline
1. Occurrence and distribution2. Composition3. Longevity4. Astrobiology5. The future
T109 Feb 2015
T104 August 2014
Latitude line incr. are 5o
Lack of observed waves on the large seas may be seasonal
Prime XM
Solstice Mission
Now
Lorenz, Tokano and Newman, Planet. Space Sci., 2011
Sea surface• Winds on Titan have formed
dunes in many regions, apparent wave-modified beach at Ontario
• FLAT surfaces observed to date at Titan lakes
• GCM predictions are consistent with non-detection of waves
so far, but expect to observe waves ~ 2015-2017.• Tokano GCM predicts modest
winds during summer/fall TiME season.
VIMS and ISS images and spectra of the seas and lakes as the Sun climbs north
5 microns...VIMS
Titan Mare Explorer: A Discovery mission to float across Ligeia Mare, measuring the composition, depth and atmospheric interactions of a Titan sea.
Not selected for flight
TiME Science Objectives• Constrain sea composition
– Determine the chemistry of seas to constrain Titan's methane cycle, look for patterns indicative of chemical evolution in the abundance of constituents in the liquids and analyze noble gases. Instruments: Mass Spectrometer (NMS), Meteorology and Physical Properties Package (MP3).
• Constrain sea depth– Determine the depth of the Titan sea to determine sea volumes, and thus, organic
inventory. Instrument: MP3 (Sonar).• Measure sea surface properties
– Characterize physical properties of sea liquids and how they vary with depth and position. Instrument: MP3, NMS.
– Determine how the local meteorology over the seas ties to the global cycling of methane on seasonal and longer timescales. Instrument: MP3
– Analyze the nature of the sea surface (waves, foams, scums) and the state of the atmosphere above the sea. Instrument: Descent and Surface Imagers.
The 2020’s will be the lost decade for outer solar system exploration
Titan Mare Explorer: A Discovery mission to float across Ligeia Mare, measuring the composition, depth and atmospheric interactions of a Titan sea.
The Road goes ever on and on Down from the door where it began.Now far ahead the Road has gone, Let others follow it who can!Let them a journey new begin, But I at last with weary feetWill turn towards the lighted inn, My evening-rest and sleep to meet.
J.R.R. Tolkien
This is a Golden age of Planetary Exploration…but….
Budget deficits
Planetary
Be an advocate......
Be knowledgeable....
BE RIGOROUS......
BE PERSUASIVE......
Be VISIONARY......
BE YOURSELF.....
What will the next golden age of solar system exploration bring?