An analogue study of impact craters on Titan: Implications for Titan's surface age

Abstract

Titan is the only planetary body in our solar system, besides Earth, that has stable liquids on its surface and a thick, nitrogen-rich atmosphere. NASA's Cassini mission detected an unusually low number of impact craters on Titan's surface, possibly due to degradation and burial by fluvial erosion and aeolian infilling. This is similar to the reduced number of craters seen on Earth, which is a result of both endogenic and exogenic processes, like erosion and weathering. Given these similarities, Earth serves as a strong analogue for studying the preservation of Titan's craters. There are 200 confirmed craters on Earth, of which 67 are buried and therefore unobservable from orbit. This study determines the percentage of the remaining exposed and resolvable terrestrial craters that can be identified in synthetic aperture radar data (SAR), in order to estimate the number of craters we may be missing in Cassini RADAR images of Titan. The results show that only ∼60 % of the non-buried terrestrial craters are distinctly visible in radar images; the remaining 40 % were not clearly identified by the authors. These findings were further validated through a crowd-sourcing exercise, where users attempted to identify craters in a smaller sample of radar images. If a similar number of craters are obscured on Titan, it suggests that 40 % of Titan's non-buried craters are not visible in the Cassini RADAR data set. Thus, the surface age of Titan could be ∼1.5-2× older (∼300 Ma – 2 Ga) than currently hypothesized (∼200 Ma – 1 Ga).