Geometric Analysis of Surface Features on Titan Using Terrestrial Analogs
Narkevic, David Ash
MetadataShow full item record
Titan, a large (radius = 2576 km) moon of Saturn shrouded by an opaque nitrogen atmosphere, has been a prime candidate for youthful extraterrestrial volcanism since the discovery on Neptune's moon Triton of cryovolcanism (eruptions of water or other volatiles onto planetary surfaces where they would normally be frozen) in 1989 because of similarities in Titan's and Triton's calculated bulk compositions. After the arrival of the Cassini spacecraft at Titan in 2004 with a radar instrument capable of imaging Titan's surface, potential volcanic morphologies were identified on the surface. At present, however, alternative processes such as impact cratering, lacustrine processes, and tectonism remain valid alternatives for forming these (possibly volcanic) features, and thus whether the planet is volcanically active remains unknown. The presence, or lack, of volcanism on Titan would have significant implications for its thermal evolution, specifically regarding whether it underwent melting during accretion, and whether ongoing radiogenic heating was sufficient to maintain subsurface melt. This investigation uses a variety of depressions with known origins on other planetary bodies as possible analogs for basins detected on Titan to determine which are most morphologically similar. Impact craters, volcanic calderas, and lakes on Earth; impact craters and volcanic calderas on Mars; and impact craters on Ganymede were analyzed in terms of size, circularity, aspect ratio, and fractal dimension to generate a database of geometric parameters. This serves as a basis of comparison for previously identified Titanian impact craters, depressions of unknown origin, and particularly subcircular depressions filled with liquid hydrocarbon that resemble karst lakes, but may also be calderas. I find that different types of features exhibit patterns when comparing these four parameters that can allow for identification of an unknown feature by comparison. One feature, a dry depression at 70.74° N, 358.87° E, is identified by this process as having a likely volcanic origin, and morphological and topographical data support this assessment.