Beneath Titan

I’ve been soaking up the rays of pure information streaming from the now-ongoing Division of Planetary Sciences Meeting at Cornell University. Specifically today’s late morning session on the subsurface of Titan. The science is amazing, surprising, and brand new.

Starting the session was a talk by Ralph Lorenz at JHU/APL, who presented work done with his coauthors on Cassini radar data for the Titanian surface. It turns out Titan is pretty flat. The Cassini radar data presented by Dr. Lorenz point to a rolling, flattened landscape punctuated by sluggish methane lakes and gurgling oily rivers. The highest point recorded so far on Titan is only about 2 kilometers above the lowest point. On Earth the difference is more like 20 km, and we have a lot more gravity pulling the Earth into a perfect sphere. The Cassini data show the highest “mountains” on Titan are only 200 to 500 m tall, which is a low hill on Earth. Lorenz capped his talk showing a section of the Titanian surface that is completely flat – within the resolution of the radar – and gently slopes down a kilometer in altitude across 300 km of smooth ski run.

The second talk was presented by Giuseppi Mitri at JPL, who along with coworkers had put together some very cool Cassini radar data that integrate to show a Titanian subsurface dominated by a subtitanean ocean of ammonia water. This makes Titan more like Europa, with its own global water ocean trapped beneath a thin crust of water ice. Ten kilometers beneath the Titanian surface, the hard ice gives way to liquid water. This is an alien ocean, with ammonia instead of table salt making it briny and bitter. This reeking ocean would have a very high pH, making any form of conventional life impossible except possibly for a few very hardy extreme halophiles. On Earth such organisms can thrive in very high salinity and at very high pH, but few other life forms can manage that feat. High pH is much more difficult for bacteria to defeat than low pH. Still, with a surface saturated by hydrocarbons and an atmosphere full of molecular nitrogen and complex organic molecules, poised above a sea of reduced nitrogen in liquid water… there might be some interesting redox chemistry possible down there, and redox chemistry is the driver for life.

More on the following talks, but first I’m going to go watch Heroes with the wife.


~ by Planetologist on October 13, 2008.

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