Penetrating Titan's Hazy Organic Stew

ASTROCHEMISTRY

The upper atmosphere of Saturn's giant moon Titan, with its obscuring methane haze, also is awash with complex hydrocarbons, planetary scientists announced last week. During a close flyby of Titan on April 16, mass and ion spectrometers aboard NASA's Cassini spacecraft detected organics containing as many as seven carbon atoms, in addition to nitriles. Cassini imaged the moon's opaque orange-yellow atmospheric blanket at visible wavelengths (left). A false-color composite (right), created by combining two infrared images and a visible image, reveals surface features as green and atmospheric methane as red. The discovery of a wide variety and high concentration of hydrocarbons in Titan's atmosphere surprised scientists: They had expected that the compounds, produced when ultraviolet light photolyzes atmospheric methane and nitrogen, would immediately condense and rain down onto Titan's surface. Earlier this year, the European Space Agency's Huygens probe, which landed on Titan, found evidence of a hydrocarbon goo that was coating trenched regions of the moon's surface.