The Cassini Space Probe has measured the depth of a 40-kilometer-long stretch of Kraken Mare, the largest sea on Saturn's moon Titan.
Shortly before capturing the first images showing Titan's hydrocarbon seas with sunlight bouncing off of them, Cassini used radar to measure a strip of Kraken's eastern side. Depths varied from 20 to 35 meters, but NASA cautions that these may be far from the deepest parts of the sea.
The area studied during the August flyby is near the mouth of what on Earth would be considered a flooded river valley. Even though Titan's rivers and seas are filled with hydrocarbons, probably methane and ethane rather than water, it is thought the processes of erosion and flooding are similar.
The study was part of a 200 kilometer sweep across the breadth of Kraken, but for the majority of this the results came back blank. NASA concluded that, “For the areas in which Cassini did not observe a radar echo from the seafloor, Kraken Mare might be too deep for the radar beam to penetrate.” An alternative possibility is that the still unknown make up of Titan's seas varies, and the blank stretches represent more absorbent liquids.
The land around parts of the Kraken sea is quite steep, and if this continues beneath the surface, some sections might be deep enough to host the mythical beasts after which it is named.
At the same time, two bright features were seen in Kraken Mare that had not been visible on previous flybys. These may be related to the mysterious feature dubbed “magic island” that was spotted with a radar in Ligeia Mare last July before disappearing again a few days later.
This time, however, both the Cassini radar and Visible and Infrared Mapping Spectrometer (VIMS) were focused on the right location, bolstering the opportunity to identify what causes these bright spots. Patches of waves or some form of debris are currently the favored explanations, with some alternatives such as fog or submarine icebergs having been ruled out.
The findings were presented to a workshop at the Planetary Sciences Division of the American Astronomical Society.
In January, NASA plans to do another radar sweep of Punga Mare, the smallest of the three bodies large enough to be designated seas. The same pass will provide an opportunity for researchers to study Ligeia for further clues as to the nature of these intermittent bright spots. This will be the last attempt to study Titan's seas and sea floors before Cassini makes its final dive into Saturn to collect as much data as it can on the atmosphere of our solar system's second largest planet before being crushed to oblivion.