Ramparts Discovered Around Titan LakesAugust 27, 2019 / Posted by: Yael Kovo
Right: T16 SAR image of Viedma Lacus. Cyan arrows denote portions of the perimeter of the rampart feature, a SAR-bright apron that encloses nearly the entire lake. Yellow arrows denote portions of the raised rim. Top Left: Zoom into the raised rim portion of the lake perimeter, denoted by the white box in the right image. The rim appears eroded in multiple sections; Bottom Left: Conceptual model of a lake with a rampart and rim (not to scale).
Cassini observations of Titan have revealed ~650 polar lakes and seas. Modeling efforts, supported by Cassini data, suggest the liquid composition to be a mixture of methane/ethane with a contribution of dissolved nitrogen. The surface of Titan has abundant carbon-rich molecules (hydrocarbons) that have been shown to form amino acids, the building blocks of proteins needed for life, when exposed to liquid water in laboratory simulations.
Lake formation remains an open question in Titan science. The discovery of ramparts around a few of these lakes might help shed light on the formation of Titan’s lakes in general and provide clues on the composition and astrobiology potential of these areas.
Scientists, including members of the NAI’s JPL Habitability of Hydrocarbon Worlds: Titan and Beyond team, discovered raised rampart features around these lakes (which are distinct from raised rims), and appear as Single Aperture Radar (SAR)-bright mound-like annuli extending away from the lake for up to tens of kilometers from the shoreline.
Investigation of the infrared and microwave characteristics of these features using Cassini Visual and Infrared Mapping Spectrometer (VIMS) and RADAR data shows that the infrared spectral response of the raised ramparts is very similar to that of some empty lake floors. This suggests that both areas are made from or are covered by a similar material.
These observations provide first insights into the possible mechanisms leading to the formation of the raised ramparts that are discussed here.
Excerpted from the recent paper, “Spectral and emissivity analysis of the raised ramparts around Titan’s northern lakes”.
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