Cassini targets TITAN.

TITAN (Satellite); SPACE exploration; MARS (Planet); SATURN (Planet); ASTRONOMICAL research; WAITE, Hunter; SPACE vehicles; NITROGEN spectra; ATMOSPHERIC research; SPECTROMETERS

The article reports on the Cassini spacecraft's exploration of Saturn's moon, Titan. After a 7-year journey, Cassini plunged within 730 miles of the haze-shrouded surface. The images reveal a high-contrast surface with a complex interplay between the bright and dark expanses. The surface also features a multitude of bright streaks. The streaks have planetary scientists seeing red--as in Red Planet Mars. The streaks on Titan appear similar, although that's no guarantee they are. Neither the radar experiment nor imaging cameras detected any specular reflections, or bright glints, coming off a liquid surface. Radar observations from Earth have shown such reflections. The radiometry confirmed observations made with the Visual and Infrared Mapping Spectrometer (VIMS) that showed a surprisingly uniform surface of carbon-containing compounds, with little difference in composition between the light and dark areas. Neither the imaging cameras nor the radar experiment saw any clear-cut evidence of impact craters. Another Cassini instrument, the magnetometer, attempted to probe beneath Titan's surface. The most significant discovery made by the Ion and Neutral Mass Spectrometer is that Titan may have lost three-quarters of its atmosphere over the age of the solar system. INMS team leader Hunter Waite of the University of Michigan says the nitrogen-15 to nitrogen-14 ratio is "off the scale"--far higher than the ratios seen on Earth, Venus, Mars, and Jupiter. INSETS: MOONS GALORE;BACK AT THE PLANET;COUNTDOWN TO LANDING;WHAT'S AHEAD FOR CASSINI?