A CRATER DATABASE FOR IAPETUS

Iapetus, the third largest moon of Saturn, is best known for its hemispherical albedo dichotomy and enigmatic large equatorial ridge. One of the most heavily cratered bodies in the Solar System, Iapetus has preserved its lifetime of cratering. Craters are useful for studies of satellite's surfaces; their density, shape or orientation can provide information on resurfacing events, local strain or deformation. Despite the in-depth studies focused on Iapetus, no global digital database of craters exists. Digitization of craters allows analysis of their distribution with respect to both the ridge and albedo dichotomy. Although simple, the global database will serve as a reference for future work examining morphological characteristics of craters to examine properties of the unique surface features of Iapetus.

Craters were mapped using ArcGIS. A recently released global mosaic is used as the base map. The mapped craters are joined to a database which includes their coordinates and size. The database will be expanded to include (but not be limited to) morphological classifications (simple, central peak, central peak basin, peak-ring basin). A minimum crater diameter will be set to maintain even coverage, and resolve certain distribution errors based on current resolution differences on Iapetus' surface.

Identification of craters within close proximity of the equatorial ridge merit special attention, observing their individual relative orientation with respect to the ridge. The deformation and/or dip of craters may identify structural traits of the ridge, and possibly constrain formation models. For example, if a process of uplift formed the ridge, this would result in nearby craters dipping away from the ridge showing evidence of strain. Alternatively a ridge resulting from the relaxation of the fossil bulge may cause craters to dip towards the ridge.

Analysis of Iapetus has lagged behind the other icy satellites because of the limited, low resolution coverage by Voyager. Recent data from the Cassini mission and the release of a global Iapetus mosaic allows for analysis to be continued on a global scale with better resolution.