Titan’s Lakes and Seas Jonathan I. Lunine Cornell University

Outline 1. Occurrence and distribution 2. Composition 3. Longevity 4. Astrobiology 5. The future

Outline 1. Occurrence and distribution 2. Composition 3. Longevity 4. Astrobiology 5. The future

Ideas about surface methane and ethane on Titan were stimulated by Voyager 1 in 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 Mike Carroll The seas are the third of three known carbon reservoirs

Outline 1. Occurrence and distribution 2. Composition 3. Longevity 4. Astrobiology 5. The future

ethane in Ontario Lacus (Brown et al. 2008) We do not know the bulk ethane/methane/propane abundance in the seas Theoretical calculation Cordier et al 2011

Outline 1. Occurrence and distribution 2. Composition 3. Longevity 4. Astrobiology 5. The future

Seasonal: Lora et al., 2011 Orbit precession Aharonson et al Sunlight received at the surface. Prime Equinox Solstice

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 Ocean HP-Ice Layer Ice/Hydrates hot water moves through hydrated silicates to ocean Actively dehydrating rock core raises heat flux by % The ethane sinks in the crust...into the ocean? Density versus temperature of clathrate

Outline 1. Occurrence and distribution 2. Composition 3. Longevity 4. Astrobiology 5. 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 distribution 2. Composition 3. Longevity 4. Astrobiology 5. The future

T109 Feb 2015 T104 August 2014 Latitude line incr. are 5 o

Lack of observed waves on the large seas may be seasonal Prime XMXM 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 ~ 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 feet Will 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 Plan etar y

Be an advocate Be knowledgeable.... BE RIGOROUS BE PERSUASIVE Be VISIONARY BE YOURSELF.....

What will the next golden age of solar system exploration bring?