CJ Hansen Earth 390
Source: Cassini Orbiter Titan: Basic Facts
-Saturn’s largest moon, second largest satellite in solar system
-Discovered by Chris aan Huygens, March 25th, 1655
-Diameter of 5150 km, (0.4 Earth Diameters)
-Only satellite with a dense atmosphere
-Interes ng features include hydrocarbon lakes, subsurface water ocean, and a vortex at the south pole
Size Comparison To-Scale Discovery and Naming
-Discovered by Chris aan Huygens, March 25th, 1655 -a er discovering rings of Saturn, surprised to discover that a moon orbited as well
-Ini ally named “Saturn’s Moon” by Huygens, later named Titan by John Herschel in 1847 -Saturn was the Roman version of the Greek Cronus, who was a Titan
Huygens
Herschel Missions to Titan
Pioneer 11: Arrived September 1st, 1979
Voyager 1: Arrived November 12th, 1980
Cassini-Huygens: Arrived July 1st, 2004 Pioneer 11
-Took some images of Titan, as well as temperature readings
-Temperature found to be very cold
Saturn and Titan
Titan Voyager 1
-Flyby of Titan considered cri cal to mission
-Data allowed for constraints on the mass and size of Titan, as well as atmospheric composi on
-Thick atmospheric haze con nued to obscure the surface
-Layers of haze can be seen in voyager 1 images Cassini-Huygens Mission composed of two probes:
Cassini Orbiter -Equipped with various spectrographs, able to image in microwave infrared, op cal, and ultraviolet spectra -RADAR instrument specifically designed to unveil the surface features of Titan -Currently orbi ng Saturn on its second extended mission
Huygens Lander -Landed on surface of Titan January 14th 2005 (Sent data for ~90 min a er landing) -Instruments allow for composi onal analysis, imaging, and other measurements -Most distant successful landing of any human made probe Cassini Images
Imaging Science Subsystem (ISS)
Visual and Infrared Mapping Spectrometer (VIMS)
RADAR Huygens Images
Images taken during descent and a er landing Atmosphere Approximately 98% Nitrogen, 2% Methane and Hydrogen (Coustenis & Taylor 2008)
Atmosphere makes Titan the most earthlike body in the solar system -Methane acts similarly to water, forming clouds, rain, rivers, lakes
Tan et al. 2014 finds that liquids on Titan exhibit exo c behavior: the density increases with temperature but decreases with pressure at temperatures above 89.8 K
Tan et al. 2014 Methane Clouds
Atreya et al. 2006 finds that sunlight should have converted all of Titan’s methane to more complex molecules, therefore there is likely an interior source of methane on Titan
Important to note: Titan’s seasons are determined by Saturn’s orbit. Northern Hemisphere summer began in 2010, atmosphere ac vity may change with season as me progresses.
Clouds imaged over a 2 day period by Cassini’s ISS South Polar Vortex
Cloud at south pole rotates every 9 hours, much faster than ~15 day rota on of Titan
Cloud formed as southern hemisphere moved into autumn
Contains high amounts of hydrogen cyanide (de Kok 2014) Hydrocarbon Lakes
Northern lake region: even with change of season, lakes Specular reflec on confirms retain shape existence of surface lakes, discovered in 2009 Lakes tend to be concentrated around the poles
Cordier 2011 uses a computer model to determine the composi on of the lakes: ~75% ethane, ~10% methane, ~7% propane, ~8% hydrogen cyanide, nitrogen, butane, others Large bodies are called “Mare” while the smaller bodies are called “Lacus” Size comparison: Ligeia Mare vs. Lake Superior Hydrocarbon Lakes
Tan et al. 2014 Forma on of Titan
-Mandt, 2014 concluded that the planetesimals of Titan had to have formed in the cold Protostellar Nebula, not in the warm Saturnian Nebula -This comes from low abundancies of NH3, which form in higher temperatures associated with Saturn’s forma on
-Asphaug & Reufer, 2012 suggest that Titan was formed as the result of numerous collisions -Believe that Saturn had a system similar to the Galilean moons pre-coalescence that became unstable -Could explain Titan’s high orbital eccentricity (0.029) -also a possible explana on of Trojan moons
Large degrees of dal warping indicate a subsurface ocean (Mitri, 2014) Future Missions
Sadly, nothing is certain, but NASA awarded a grant to a project looking into the possibility of a submarine to explore Kraken Mare
Previous proposals such as the Titan Saturn System Mission have been rejected, giving priority to Jupiter/Europa missions References
Asphaug & Reufer, Late origin of the Saturn System, Icarus, vol. 223, pp 544-565, 2013
Atreya et al., Titan’s methane cycle, Planetary and Space Science, vol. 54, pp 1177-1187, 2006
Cordier et al., Titan’s lakes chemical composi on: sources of uncertain es and variability, European Planetary Science Congress Abstracts, vol. 6, p 595, 2011
Coustenis & Hertzig, Cassini-Huygens results on Titan’s surface, Research in Astronomy and Astrophysics, vol. 9, no. 3, pp 249-268, 2009
Elachi et al., RADAR: The Cassini Titan Radar Mapper, Space Science Reviews, vol. 115, pp 71-110, 2004
Mandt et al., Protosolar Ammonia as the Unique Source of Titan’s Nitrogen, The Astrophysical Journal Le ers, vol. 788, pp 24-28, 2014
Mitri et al., Shape, topography, gravity anomalies and dal deforma on of Titan, Icarus, vol. 236, pp 169-177, 2014
Tan et al., Titan’s liquids: exo c behavior and its implica ons on global fluid circula on, Icarus, vol. 250, pp 64-75, 2015
Cassini-Huygens Images: h p://saturn.jpl.nasa.gov/photos/?subCategory=10