From: University of Arizona
Posted: Monday, November 8, 2004
A strikingly bright, lobate feature has turned up in one of Cassini's first radar images of Saturn's moon Titan.
"It may be something that flowed," Cassini radar team member Ralph Lorenz of the University of Arizona said. "Or it could be something carved by erosion. It's too early to say.
"But it looks very much like it's something that oozed across the surface. It may be some sort of 'cryovolcanic' flow, an analog to volcanism on Earth that is not molten rock but, at Titan's very cold temperatures, molten ice."
Cassini radar mapped about one percent of Titan's surface during the Cassini spacecraft's first close Titan flyby Oct. 26. The radar survey covered a strip 75 miles wide (120 kilometers) and 1,200 miles (1,960 kilometers) long in Titan's northern hemisphere.
Cassini was flying about 1,550 miles (2,494 kilometers) above Titan's surface, with its radar centered at about 45 degrees north, 30 degrees west, when it mapped the 90-square-mile (230-square-kilometer) area shown in the new radar image.
The Cassini radar team presented the image today at the 86th annual meeting of the American Astronomical Society Division of Planetary Sciences in Louisville, Ky.
The radar instrument works by bouncing radio signals off Titan's surface and timing their return. The more signal reflected back to the spacecraft, the brighter the imaged area. Turning radio signals into radar images is time consuming because so many numerical calculations must be made. "There's no such thing as a 'raw' radar image," Lorenz said. But two days after the Oct. 26 flyby, Cassini scientists knew that Titan is no impact-crater-pocked dead world, but a much more interesting place. Titan's surface is young -- it's been shaped by dynamic geologic processing, Lorenz, Cassini interdisciplinary scientist Jonathan Lunine of the University of Arizona, and other Cassini scientists agree.
Given this newest image, Lunine said, "Radar has provided the first evidence for possible young cryovolcanism on Titan's surface. Now our challenge is to find out what is flowing, how it works, and the implications for Titan's evolution."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The radar instrument team is based at JPL, working with team members from the United States and several European countries.
PHOTO CAPTION: Oozing across Titan
This synthetic aperture radar image of the surface of Saturnšs moon Titan was acquired on October 26, 2004, when the Cassini spacecraft flew approximately 2,500 kilometers above the surface and acquired radar data for the first time.
The radar illumination was from the south. Dark regions may represent areas that are smooth, made of radar-absorbing materials, or are sloped away from the direction of illumination. A striking lobate bright feature stretches from upper left to lower right across this image, with connected armsš to the east. The fact that the lower (southern) edges of the features are brighter is consistent with the lobate structure being raised above the relatively featureless darker background. Comparisons with other features and data from other instruments will help to determine whether this is a cryovolcanic flow, where water-rich liquid has welled up from Titanšs warm interior.
The image is about 150 kilometers (90 miles) square, and is centered at about 45 N, 30 W in the northern hemisphere of Titan, over a region that has not yet been imaged optically. The smallest details seen on the image are around 1 kilometer (.62 mile) across. Features are less clear at the bottom of the image where the viewing was less favorable. A faint horizontal seam between the radar beams can be seen half way up in this preliminary product.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASAšs Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The RADAR instrument team is based at NASAšs Jet Propulsion Laboratory, Pasadena, Calif., working with team members from the USA and several European countries. (Image credit: NASA/JPL)
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