Astrobiology of Titan


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Astrobiology of Titan and early results from Cassini­Huygens Lecture at Penn State Astrobiology Workshop for Educators July 28th 2005 Dr Conor A Nixon University of Maryland/NASA GSFC/Cassini CIRS Team Overview • Saturn system summary. • Titan ­ the enigmatic moon. • Why go back? • The Cassini­Huygens spacecraft. • Latest and greatest Cassini pictures and results. • Huygens landing. • Where do we go from here? Facts about Saturn (i) • Saturn is the 6th planet from the Sun, 9.5 times as far as the Earth. • Saturn is the 2nd largest by mass and radius. • Saturn is mostly composed of the same materials as the Sun: H2 and He. • Other common elements such as C, N, O, P are hydrogenated: CH4, H2O, PH3, NH3 etc. • Condensates such as NH3 ice form the visible cloud deck: there is no ‘surface’ like the Earth. Ready to go… • Cassini on display before launch, fall 1997 • Cassini at launch pad, on rocket, awaiting fairing. Blast­off! • Cassini­Huygens was launched at 4:43 a.m. EDT on October 15th 1997 from Cape Canaveral Air Force Station Cassini takes the scenic route to Saturn… Titan ‘boulders’ • Huygens bumped rather than splashed on Titan’s surface. • This image shows the ground near the spacecraft. • The ‘boulders’ are probably water ice. • The below­center ‘boulder’ is actually just a pebble, 6 in across. What have we learned? • Titan has not given up its secrets easily! • But we have learned: – Titan appears to be mostly dry; no widespread methane or ethane oceans or seas. – Methane condensation produces clouds around the south pole with possible rainfall. – The surface is young, indicating resurfacing by outflows, tectonics, impacts in last 100­300 Myr. – Photochemistry is active high in the ionosphere. What is still unanswered? • Again, we have raised many new questions: – are we seeing lakes near the south pole, or something else? – are we seeing cryovolcanos? – if not, where does the methane come from and go to? – what are the cat scratches? – when, what and how were the ‘shorelines’ near the landing site made? THE END… … FOR NOW!

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