Titan Shows Its Surface to Cassini

Time to Titan their theories; Cassini scientists are both fascinated and puzzled by surface features coming to light from the first encounter July 2 with Saturn’s large atmosphere-shrouded moon Titan.  At a news conference July 3, some of the initial findings were unveiled: methane clouds hovering over the south pole, linear dark and light markings (signifying possible tectonic activity), and circular and concentric features that might be related to impacts.  A composite image produced by filters from the visual and infrared mapping spectrometer (VIMS) was released.  Some of the more puzzling features include:

• No glint of large liquid regions was found (see 10/16/2003 headline).
• The dark and light areas have opposite compositions than expected.  The light areas, thought to be ice, may be hydrocarbons, and the dark areas, thought to be hydrocarbons, may be the ices. 
• A huge cloud of neutral hydrogen, bigger than Saturn and its rings, follows Titan around.  The magnetospheric imaging instrument (MIMI) imaged this cloud which consists of molecules stripped away from Titan’s upper atmosphere.

Data should get better and better.  Cassini has 45 targeted flybys of Titan planned.  This one was from 210,600 miles away, but on October 26, Cassini will zoom past Titan from only 750 miles.  Over the coming years, the radar instrument will map most of the surface like Magellan did Venus.  The most adventurous day of all will be the Jan. 14, 2005 landing of the Huygens Probe on the surface.

These findings are consistent with prior observations that are making it difficult to believe Titan has been in its current state for 4.5 billion years.  The atmosphere is eroding quickly and leaving traces of its erosion in the huge cloud that is leaking away.  No large lakes or deposits of hydrocarbons are yet visible.  These preliminary interpretations will await further elucidation from the high resolution data in the flight plan.  Stay tuned.