Synergy of Cassini SAR and altimeter acquisitions for the retrieval of dune field characteristics on Titan

Abstract

This work focuses on the retrieval of Titan’s dune field characteristics addressing different radar modes. The main purpose of the proposed work is to exploit a possible synergy between SAR and altimeter acquisitions modes to provide information about dune field. Cassini has performed 86 Titan flybys in which several observations of dune fields have been collected in altimetry mode. There are several cases in which SAR and altimeter have been acquired over same areas covered by dune fields, such as during T28 (SAR) and T30 (altimeter) flybys. Altimetry together with SAR data have been used to derive the rms slopes of dunes (large scale) over Fensal area, this information has been employed to calculate SAR incidence angle with respect to dunes. We extracted backscattering coefficients of bright and dark areas detected in the analyzed SAR image in order to evaluate the angular response of scattering. Through the Geometric Optics model we retrieve roughness values (small scale rms slope) for both dune bright and dark areas

Dune Height Estimation on Titan Exploiting Pairs of Synthetic Aperture Radar Images With Different Observation Angles

“…Solving the equation using the mean dune-to-dune spacing found, namely 2.5 km, resulted in dunes higher than 400 m. This value is well beyond the ranges of dune heights found on Titan [5], [10], [17], [18] as well as using Earth analogs [19]. This result tells us that probably the initial assumption of material homogeneity is not true.…”

Dual Frequency Orbiter-Radar System for the Observation of Seas and Tides on Titan: Extraterrestrial Oceanography from Satellite

“…which for the proposed system reach a value of R az = 2 m. Based on the ground resolution requirements, a multi-look average by a factor of 10 can be always performed, therefore according to (7), the radiometric resolution requirements in Table 3 can be always achieved:…”

“…Hundred meters high dunes fields [2], which are spread across the equator (±30 • in latitude), covering about 15% of the whole surface [3,4] have been observed by the instruments in different modes (i.e., SAR, altimetry, radiometry). Their shape is believed to be the result of a general eastward transport of cohesive organic solids [5], their morphology being similar to the terrestrial dunes seen in Namib, Sahara, and Arabian deserts [6], and their material is likely to be composed by solid hydrocarbons, mixed with water ice at interdune [7][8][9][10]. Instruments on board Cassini also revealed the presence of mountains [11][12][13], craters [14] with possible cryovolcanic origin [15], in addition to a complex hydrological system that is made of liquid hydrocarbons with possible subsurface connection [16].…”

Volume Of Impact-derived Ejecta And Constraints On Aeolian Processes And Yardang Formation On Venus

“…On Titan, linear dunes dominate the arid lower latitudes and contain around 10 5 km 3 of sediment (Rodriguez et al 2014). Most are between 55 and 110 m tall and extend for 10s to 100s of kilometers with widths of ⇠1 km and spacings of 1-3 km (Poggiali et al 2012;Rodriguez et al 2014). These dunes are thus much longer than the Mead features and significantly lower elevation, although they are spaced at similar intervals and both relatively narrow compared to their lengths (Figure 1.7, panel E).…”

“…On Titan, linear dunes are ⇠55 to 110 m tall (Poggiali et al 2012). If the Mead features are treated as dunes with the same height, the volume of sediment in the southern field would be 2200-4400 km 3 .…”