Cassini's infrared camera sees tall mountains on Saturn's moon Titan
Wed Dec 13, 2006 at 15:24 UTC
The infrared-sensitive camera on NASA's Cassini spacecraft has photographed the tallest mountains ever seen on Saturn's moon, Titan.
The mountain chain is nearly a mile high (1.5 kilometers), 93 miles long (150 kilometers) and 19 miles wide (30 kilometers). The mountains are topped by bright, white material which may be methane or other organic (carbon-containing) "snow."
"We see a massive mountain range that reminds me of the Sierra Nevada in the western United States," said Cassini scientist Robert H. Brown of the University of Arizona Lunar and Planetary Laboratory in Tucson. Brown is head of Cassini's visual and infrared mapping spectrometer (VIMS), which imaged the mountains in Titan's southern hemisphere during the Oct. 25, 2006 flyby.
The camera took its highest-resolution infrared views of Titan ever during this flyby, resolving surface features as small as 400 meters, or about 440 yards. Other features seen in the high-resolution VIMS images include fields of dunes and a deposit that resembles a volcanic flow.
If Titan were Earth, the mountains would be at latitudes near New Zealand. They probably formed as mid-ocean ridges form on Earth: The surface crust pulls apart, and material beneath the crust wells up through the crack, creating a ridge.
"These mountains are probably as hard as rock, made of icy materials, and are coated with different layers of organics," said Larry Soderblom of the U.S. Geological Survey, Flagstaff, Ariz., a Cassini interdisciplinary scientist.
"There seem to be layers and layers of various coats of organic 'paint' on top of each other on these mountain tops, almost like a painter laying the background on a canvas," Soderblom said. "Some of this organic gunk falls out of the atmosphere as rain, dust or smog onto the valley floors and mountain tops, which are coated with dark spots that appear to be brushed, washed, scoured and moved around the surface."
Image Credit: NASA/JPL/University of Arizona
High resolution image
This composite image shows a massive mountain range running just south of Titan's equator. Near the center of the image, the mountain range runs from southeast to northwest. It is about 150 kilometers long (93 miles) and 30 kilometers (19 miles) wide and about 1.5 kilometers (nearly a mile) high. This range, and smaller ranges to the west and east of the main range, probably results from material welling up below as the crust of Titan is pulled apart by tectonic forces.
This image was obtained during an Oct. 25 flyby designed to obtain the highest resolution infrared views of Titan yet. Cassini's visual and infrared mapping spectrometer resolved surface features as small as 400 meters (1,300 feet). This composite image was taken at a distance of 12,000 million kilometers (7,200 million miles) from Titan. This image was constructed from images taken at wavelengths of 1.3 microns shown in blue, 2 microns shown in green, and 5 microns shown in red.
Image Credit: NASA/JPL/University of Arizona
High resolution image
This image set was taken at a distance of 15,000 kilometers (9,300 miles) from Titan and shows two views of an area riddled by mountain ranges that were probably produced by tectonic forces.
Near the bottom of the right image, a band of bright clouds is seen. These clouds are probably produced when gaseous methane in Titan's atmosphere cools and condenses into methane fog as Titan's winds drive air over the mountains. It was once thought that these recurring clouds were produced by volcanic activity on Titan, but this image calls that idea into question.
These views were obtained during an Oct. 25 flyby designed to obtain the highest-resolution infrared views of Titan yet. Cassini's visual and infrared mapping spectrometer resolved surface features as small as 400 meters (1,300 feet). The images were taken at wavelengths of 1.3 microns shown in blue, 2 microns shown in green, and 5 microns shown in red.
Image Credit: NASA/JPL/University of Arizona
High resolution image
This image is a composite of several images taken during two separate Titan flybys on Oct. 9 (T19) and Oct. 25 (T20).
The large circular feature near the center of Titan's disk may be the remnant of a very old impact basin. The mountain ranges to the southeast of the circular feature, and the long dark, linear feature to the northwest of the old impact scar may have resulted from tectonic activity on Titan caused by the energy released when the impact occurred.
The Oct. 9 images form the background globe for context, and the most recent images from the Oct. 25 flyby are overlaid. The Oct. 9 images were taken at an average distance of about 30,000 kilometers (18,000 miles). The Oct. 25 images were taken at a distance of 12,000 kilometers (7,200 miles). The images were taken at wavelengths of 1.3 microns shown in blue, 2 microns shown in green, and 5 microns shown in red.
Image Credit: NASA/JPL/University of Arizona
High resolution image
This image composite contains a radar image taken during a February 2005 (T3) flyby, and overlaid are images from the visual and infrared mapping spectrometer taken on Sept. 7, 2006, (T17) and Oct. 25, 2006 (T20).
The thin strip is the infrared image taken on the inbound leg of the T20 flyby and crosses the radar image near an area with a small, crater-like feature. In the radar image a faint fan of material seems to originate at the crater, and the portion of the infrared image that crosses the faint fan shows both a large brightness contrast and very sharp boundaries. The fan-like deposit has such sharp boundaries and strong contrast with its surroundings that it supports the idea that the deposit seen in the radar images is a flow of material erupted from the small crater. This may be the strongest evidence yet of cryovolcanism on Titan. The infrared image was taken at a distance of 1,100 kilometers (680 miles) from the surface of Titan and resolves features as small as 400 meters (1,300 feet).
The infrared images were taken at wavelengths of 1.3 microns shown in blue, 2 microns shown in green, and 5 microns shown in red.
Cassini scientists combined the new infrared data with radar data from previous flybys to better understand the height and composition of Titan's geologic features. The shadows of the mountains are seen in the infrared images, for example, while the shapes of the mountains are seen in radar. Combining these different kinds of data is essential for scientists studying Titan's geologic processes.
The Oct. 25 infrared images also reveal a fan-shaped feature, which Brown said is probably a remnant of a volcanic flow. Cassini radar imaged this fan-shaped feature, and also a large, circular feature that appears to be the source of the flow, in less detail on a previous flyby.
"The evidence is mounting that this circular feature is a volcano," said Rosaly Lopes, radar team member at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "With radar data alone, we identified it as a possible volcano, but the combination of radar and infrared makes it much clearer."
Clouds lie near the wrinkled, mountainous terrain in Titan's southern mid-latitudes. Their source has baffled scientists. "These clouds are probably methane droplets and may form when the air on Titan cools as it is pushed over the mountains by the Titanian winds," Brown said.
The new infrared images also clarify the composition of dunes that run across much of Titan. The dunes, built on water-ice bedrock, seem to consist of sand grains made of organics, Brown said.
University of Arizona News Release
