An Overview of the Bathymetry and Composition of Titan’s Hydrocarbon Seas from the Cassini RADAR Altimeter
Résumé
The Cassini RADAR’s altimetry mode has been successfully used for probing the depth and composition of Titan’s hydrocarbons seas. In May 2013, during the spacecraft’s 91stflyby of Titan (T91), the instrument demonstrates its capabilities as a radar sounder, presenting a unique opportunity to constrain direct measurements of the depth and composition of Titan’s second largest sea, Ligeia Mare. Later, observations of Kraken Mare and Punga Mare were planned and executed in August 2014 (T104) and January 2015 (T108), respectively. While most of the seafloor was not detected at Kraken, suggesting the sea was either too deep or too absorptive in these areas to observe a return from the seafloor, shallow areas near Moray Sinus did return subsurface detections. At Punga Mare, a clear detection of the subsurface was observed with a maximum depth of 120 m along the interrogated track of the sea. We will present an analysis of all three altimetric observations of Titan’s mare, as well a re-analysis of altimetry data acquired over southern Ontario Lacus. Depths measurements and liquid composition are obtained using a novel technique which makes use of radar simulations and Monte Carlo based inversions. Finally, we will show that the estimates obtained from the direct measurements described above can be used along with the RADAR’s active (i.e. Synthetic Aperture Radar) and passive (Radiometry) modes to generate bathymetry maps of areas not observed by altimetry.