Raised Rims Around Titan's Sharp‐Edged Depressions

Abstract

We perform a systematic survey of Titan's sharp‐edged depressions (SEDs) using a combination of Cassini synthetic aperture radar images and delay‐Doppler processed altimetry. We identify a characteristic bright‐dark pattern around 172 SEDs that correlates with elevated features only resolved with the highest resolution topographic data. We find that ∼75% of Titan's SEDs have elevated (∼100 m) rim features, with a preference toward larger SEDs. The differences in the distribution of SED rim presence between the north and south are slight, but the data weakly suggest that northern SEDs may be more likely to have a rim. The pattern we identify in synthetic aperture radar images is similar to quasi‐specular increases in backscatter seen on Titan's dunes. We show that this bright‐dark pattern occurs due to elevated local slopes oriented perpendicular to the radar. In general, rims occur on most of Titan's SEDs, an observation that will aid in developing and testing SED formation models.

Morphologic Evidence for Volcanic Craters Near Titan's North Polar Region

“…Topographic measurements from SARTopo (high-resolution elevation data from overlapping SAR beams, Stiles et al, 2009) and from overlapping stereo image pairs (Kirk et al, 2010(Kirk et al, , 2012 confirm that bright halos surrounding many circular depressions are elevated mounds (Figure 8; Birch et al, 2019;Hayes et al, 2017). On average, they rise about 100 m about the surroundings-and sometimes reach elevations of 300 m (Birch et al, 2019).…”

“…Mosaic has a color gradient applied according to backscatter values, browns higher than blues and blacks, exhibiting wet versus dry terrains. discussed in detail by Birch et al (2017Birch et al ( , 2019. 3The third kind of depression is approximately circular, or composed of apparently overlapping, circular depressions, that have raised, bright ramparts.…”

“…Hayes et al (2008), Hayes et al (2011), Hayes (2016), Hayes et al (2017), Birch et al (2017), and Birch et al (2019) extensively studied Titan's polar areas, followed by studies by Michaelides et al (2016) and Solomonidou et al (2019). They recognized three types of lake basins: (1) Broad depressions including the mare (seas) and largest lacus (lakes) such as Jingpo/Ontario.…”

“…(2) The second kind of depression is smaller (average size 77 km, Hayes, 2016), and the features are referred to as sharp‐edged depressions (SEDs). They have raised rims, flat floors, and steep perimeters and are discussed in detail by Birch et al (2017, 2019). (3) The third kind of depression is approximately circular, or composed of apparently overlapping, circular depressions, that have raised, bright ramparts.…”

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

“…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]. Other features, interpreted as empty lakes, have been mapped by Cassini and have been object of several works [17][18][19]. Their formation is still the object of studies, although some hypothesis regarding their endogenic origin has been recently proposed [20].…”