Cassini provides virtual flyover of Titan (video)

The new flyover maps show, for the first time, the 3-D topography and height of the 1,200-meter (4,000-foot) mountain tops, the north polar lake country, the vast dunes more than 100 meters (300 feet) high that crisscross the moon, and the thick flows that may have oozed from possible ice volcanoes.

Cassini radar team member Randy Kirk with the Astrogeology Science Center at the U.S. Geological Survey in Flagstaff, Ariz., created the maps. He used some of the 20 or so areas where two or more overlapping radar measurements were obtained during 19 Titan flybys. These stereo overlaps cover close to two percent of Titan's surface. The process of making topographic maps from them is just beginning, but the results already reveal some of the diversity of Titan's geologic features.

«« This movie makes it clear that Ganesa is generally high on the eastern side, with a few isolated very high peaks, seen in red, and low on the western side. Other high and low areas with north-south trending margins alternate to the east of Ganesa. Credit: NASA/JPL/USGS

"These flyovers let you take in the bird's-eye sweeping views of Titan, the next best thing to being there," said Kirk. "We've mapped many kinds of features, and some of them remind me of Earth. Big seas, small lakes, rivers, dry river channels, mountains and sand dunes with hills poking out of them, lava flows."

High and low features are shown in unprecedented detail at about 2.4-kilometer (1.5-mile) resolution. The maps show some features that may be volcanic flows. These flows meander across a shallow basin in the mountains. One area suspected to be an ice volcano, Ganesa Macula, does not appear to be a volcanic dome. It may still have originated as a volcano, but it's too soon to know for sure. "It could be a volcanic feature, a crater, or something else that has just been heavily eroded," added Kirk.

This movie starts with an overhead view, with north at the top. These views show rugged mountainous areas in the lower left and lower right, and blobby (lobate) flows in the top (northern) part of the region. Credit: NASA/JPL/USGS »»

The stereo coverage includes a large portion of Titan's north polar lakes of liquid ethane and methane. Based on these topographical models, scientists are better able to determine the depth of lakes. The highest areas surrounding the lakes are some 1,200 meters (about 4,000 feet) above the shoreline. By comparing terrain around Earth to the Titan lakes, scientists estimate their depth is likely about 100 meters (300 feet) or less.

More 3-D mapping of these lakes will help refine these depth estimates and determine the volume of liquid hydrocarbons that exist on Titan. This information is important because these liquids evaporate and create Titan's atmosphere. Understanding this methane cycle can provide clues to Titan's weather and climate.

Launched in 1997, Cassini completed its primary four-year mission in 2008 and is now in extended mission operations, which run through September 2010. Over the course of the mission, Cassini plans to map more than three percent of Titan's surface in 3-D. About 38 percent of Titan's surface has been mapped with radar so far. On March 27, Cassini will complete its 52nd targeted flyby of Titan.

Credit: NASA/JPL/USGS

Cassini's radar mapper has obtained stereo views of close to 2 percent of Titan's surface during 19 flybys over the last five years. The process of making topographic maps from images is just getting started, but the results already reveal some of the diversity of Titan's geologic features.

These topographic maps show the equatorial "sand sea" called Belet, and include both dark dunes and lighter, dune-free areas. Individual dunes are not resolved but the largest can be measured and have a height of 100 to 150 meters (300 to 500 feet), consistent with past estimates. The light areas are elevated, and it appears that about 200 meters (600 feet) of relief -- slightly more than the height of the dunes themselves -- is sufficient to stop or divert the dunes.

The region shown here is centered near 9° south latitude, 290° west longitude, and is about 450 kilometers (280 miles) across. The maps are in equirectangular projection with north at the top. The images used for mapping were acquired during flybys on Oct. 28, 2005, and Dec. 12, 2006 (known as T8 and T21). The T8 image is shown in black and white at the top. It has a pixel spacing of 351 meters (about 1,200 feet). Below, the same image is shown with color coding to indicate elevations, as shown by the color bar at left. The total range of relief from purple (low) to red (high) is 700 meters (about 2,300 feet). Zero elevation corresponds to a distance of 2,575 kilometers (1,600 miles) from the center of Titan, which is approximately the average radius of the satellite.

Source: Jet Propulsion Laboratory
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