The Cassini spacecraft snapped new images of Saturn's largest moon, Titan, as it readied itself for the closest flyby yet of the satellite yesterday. At 12:44 p.m EST, Cassini's planned trajectory had it sailing just 1,200 kilometers above the surface of the moon--some 300 times closer than it got during its first flyby in early July. NASA scientists hope this latest visit will provide new information about Titan's surface geology. But because Cassini can't send data back to Earth while its instruments are trained on Titan, team members had to wait about nine hours for the spacecraft to share its information payload. An announcement regarding the results is expected at noon EST today.
Eleven of Cassini's 12 instruments were scheduled for use during the close encounter. The craft's imaging radar, for one, will be employed for the first time, helping scientists to compile more detailed topographical maps of the moon. "This first close-up look at Titan should enable us to find out just how precisely our atmospheric models fit with the real situation," says Jean-Pierre Lebreton, a project scientist with the European Space Agency, "and of course we are excited about the prospect of discovering just what type of surface the Huygens probe could impact on early next year." The detachment of Huygens from Cassini is scheduled for December 24, with entry into the moon's hazy atmosphere occurring in mid-January 2005.
An image Cassini snapped during its approach (above) shows a continent-size feature of Titan's terrain that scientists have dubbed Xanadu. Although the picture has 10 times the detail of comparable snapshots taken from Earth, NASA reports that "the origin and geography of Xanadu remain mysteries at this range." Yesterday's itinerary included time for Cassini to acquire images of characteristics seen in the central-left section from a position 100 times closer. Next up for the spacecraft is a flyby with another significant Saturn moon, Tethys, on October 28.
Update: In a press conference on October 27, NASA scientists reported that Cassini's encounter with Titan went well, with the spacecraft traveling just 26 kilometers below its target altitude. The data download using the Madrid tracking station successfully returned about four gigabytes of information to NASA's Jet Propulsion Laboratory in Pasadena, Calif. According to Cassini's lead imaging scientist, Carolyn Porco of the Space Science Institute, researchers "are not quite sure what we're looking at" yet. But analysis of the data collected yesterday, as well as that expected from more than 40 other planned flybys of Saturn's biggest moon, should help them better interpret the pictures.