New Crater on Titan

Impact craters are rare on Titan. Until recently only seven had been identified definitely on Titan, so it was exciting when Cassini's Titan Radar Mapper imaged an eighth impact crater on June 21, 2011. This newly discovered crater is about 25 miles (40 kilometers) in diameter and is surrounded by a continuous blanket of ejecta (material thrown out from the crater) that appears bright to radar and extends roughly 10 to 12 miles (15 to 20 kilometers) beyond the rim. With its well-preserved ejecta and steep inward-facing walls, the new crater resembles the two other freshest known craters on Titan: Sinlap, seen in the radar image of February 2005 (PIA07368), and Ksa, seen in September 2006 (PIA08737) and imaged again in this latest flyby. One difference is that Sinlap and the new crater seem to have flat, largely featureless floors, but Ksa has a bright central peak.

Dunes, visible as dark lines on the left of the image, have been swept toward the crater by the winds of Titan. These dunes have encroached very little onto the bright ejecta, compared to those on Ksa where more than a third of the ejecta blanket on its western edge is covered by dunes.

While Saturn's other moons have many thousands of craters, Titan has very few. One reason is that Titan's dense atmosphere burns up the smaller impacting bodies before they can reach the surface. The craters that do form are often hard to recognize or disappear entirely as they are eroded over time by geological processes such as the wind-driven motion of sand and, possibly, icy volcanism.

This synthetic-aperture radar (SAR) image, centered at 12 degrees north latitude and 45 degrees west longitude, measures 150 miles (242 kilometers) high by 160 miles (257 kilometers) wide, with resolution of about 350 meters per pixel; north is at the top, and the image is illuminated from the bottom. Incidence angle varies from 15 to 25 degrees.

Photo credit: NASA/JPL-Caltech

Ksa Crater, Xanadu and Dunes on Titan

Three of Titan's major surface features-dunes, craters and the enigmatic Xanadu-appear in this radar image from NASA's Cassini spacecraft. The hazy bright area at the left that extends to the lower center of the image marks the northwest edge of Xanadu, a continent-sized feature centered near the moon's equator. At upper right is the crater Ksa, first seen by Cassini in 2006 (PIA09172). The dark lines running between these two features are linear dunes, similar to sand dunes on Earth in Egypt and Namibia.

The dune fields on Titan, Saturn's largest moon, nearly girdle the globe at latitudes from about 30 degrees north to 30 degrees south, with the notable exception of Xanadu. In this image, the dunes overlap Xanadu only slightly. They are also more widely separated and discontinuous at the boundary, a characteristic typical of dunes on Earth where the sand supply is limited. The dunes also either wind their way around or terminate at other, smaller features, including Ksa.

Cassini's Titan Radar Mapper acquired this synthetic-aperture radar (SAR) image, centered at 11 degrees north latitude and 74 degrees west longitude, on June 21, 2011. The image covers an area 350 kilometers (217 miles) high by 930 kilometers (578 miles) wide, with resolution of about 350 meters per pixel. North is at the top, and the image is illuminated from the top. Incidence angle varies from 15 to 30 degrees.

Photo credit: NASA/JPL