Titan Radar Analyses 2012

 

The table above confronts an intriguing portion of the coastline of Ontario Lacus, the largest lake of Titan's south polar region and a portion of the coastline in the south-east of France from the Nice area to the Fréjus area. The upper view of the table corresponds to a radar image of Ontario Lacus taken from the Radar Mapper of the Cassini spacecraft on January 12, 2010. A transparent rectangle was incorporated into the original radar view to unveil the topographic area of the study.
The second image, from the upper part of the table, corresponds to the zoom or the enlargement of the area of the study. This portion shows a series of bays in the eastern part of the dark Ontario Lacus. The third view corresponds to a Google Earth image of the French Riviera from the Nice area to the Fréjus area. The colour was removed from the original Google Earth view and the image is at the same scale as the second view focusing on the eastern bays.
The mosaic in the lower part of the table allows us to perform a comparative analysis of the irregular shoreline of the French Riviera and of the enigmatic bays  which mark a rupture in the relatively linear and progressive coastline of the eastern part of the Ontario Lacus depression. A scale was incorporated into the original radar view to facilitate the comparative analysis. The French Riviera area and the Ontario Lacus area are at the same scale as well.
The lake seems deeper in the bay area of Ontario Lacus than in the rest of the southern part of the lake. How to interpret ? Is it the remnant of a meteoritic impact which engendered a distortion in the topography of the eastern coastline ? Does it hide a cryovolcano or an internal source which feeds the lake with hydrocarbons such as ethane, methane and propane ? Or is it the outcome of a topographic depression which attracted a high amount of liquids which has a distortion effect or erosive effect on the coastline ? The debate is open.

Source of the upper part image: NASA/JPL-Caltech.
Source of the second image from the top of the table: NASA/JPL-Caltech.
Source of the third image from the top of the table: Google Earth.
Sources of the fourth image from the top of the table: Marc Lafferre, 2012, based on NASA/JPL-Caltech and Google Earth images.
Assembling Work: Marc Lafferre, 2012.

 

The series of images above allows us to perform a comparative analysis of Ontario Lacus, the largest lake of Titan's south polar region and some selected Terrestrial lakes. The upper view of the table corresponds to a radar image of Ontario Lacus obtained on January 12, 2010 with the Radar Mapper of the Cassini spacecraft. The second view from the top of the table is a Google Earth image revealing the Aral Sea between Kazakhstan and Uzbekistan. The third image from the top of the table is a Google Earth view showing the Bangweulu Lake in Zambia. The fourth image from the top of the table is a Google Earth image unveiling Lake Albert between Uganda and the Democratic Republic of the Congo. The fifth view from the top of the table is a Google Earth image showing the Kariba Lake between Zambia and Zimbabwe. The sixth image from the top of the table is a Google Earth view showing the Cahora Bassa Lake in Mozambique. The seventh view from the top of the table is a Google Earth image revealing Lake Chad between Nigeria and Chad. The eighth image from the top of the table is a Google Earth view showing the Etosha Pan located in the north of Namibia. The ninth image from the top of the table is a Google Earth view showing Lake Constance or Bodensee found between Germany, Austria and Switzerland.
Each image is the same size with the same scale. On the basis of the fact that Ontario Lacus is situated in a relatively arid area in terms of Terrestrial standards, on the basis of the radar images of Ontario Lacus which suggest dried-up areas in the southern part of Ontario Lacus and on the basis of a decrease in the size of the lake between two radar observations of the area, some planetary scientists advance the idea that the lake may look like a Terrestrial mudflat or a salt pan. A recent study led by Thomas Cornet of the Université de Nantes, France shows that geomorphological analyses of Ontario Lacus imply that the lake is only partially covered by liquids. A parallel is drawn between Ontario Lacus and the Etosha Pan in the north of Namibia. The Etosha pans and Ontario Lacus are located in a flat basin and the areas tend to be arid or semi arid. The southern portion of Ontario Lacus unveils topographic features or linear features which suggest that the area is not completely filled with liquids such as ethane, methane and propane and that it may resemble a mudflat.
A study led by E.P. Turtle in 2011 had shown strong evaporation processes in Ontario Lacus with a part of its shoreline which could have retreated by several kilometers between observations from the Cassini Imaging Science Subsystem. Ontario Lacus may be closer to the Aral Sea, Lake Chad, the Dead Sea or even the Etosha Pan than the Caspian Sea or the Great Lakes in North America in terms of evaporation, precipitation or depth. Will there be more precipitation and more liquids in Ontario Lacus during the next Winter season in the southern hemisphere? Is there an internal source which fuels the lake with liquids such as ethane and methane?
The depth of the lakes is closely related to the amount of liquid present, to the flow or the orientation of the  liquid and to the topography of the depression. The Aral Sea has an average depth of approximately 8.7 meters in its north part and approximately 15 meters in its south part. The maximum depth in its north part is about 42 meters. Lake Chad has an average depth of only 1.5 meters and a maximum depth of 11 meters. Lake Albert, which is an artificial lake, has an average depth of about 25 meters and a maximum depth of about 51 meters. The Kariba Lake, which is an artificial lake as well, has a mean depth of about 29 meters and a maximum depth of about 97 meters. The Cahora Bassa Lake, which is an artificial lake, has an average depth of about 20.9 meters and a maximum depth of about 157 meters. The Bangweulu Lake has an average depth of only 4 meters and a maximum depth of about 10 meters.

Post Scriptum: The colour has been removed from each Google Earth view and the scale is the same in each view in order to facilitate the comparative analysis.
Radar Image Source: NASA/JPL-Caltech.
Source of the Terrestrial Views: Google Earth.
Analysis: Marc Lafferre, 2012.

 

 

Radar Analysis 2004-2011

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