The Earth’s oceans are notoriously unexplored, and stand as a monument to the difficult of exploring underwater. But they aren’t the only unexplored seas in the solar system. Titan’s vast collection of liquid methane lakes are another challenge facing future solar system explorers.
A submarine mission to Saturn’s largest moon has long been under discussion. More recently, scientists have discovered that if such a mission was ever launched, it would have plenty of room to operate, because Titan’s largest sea is likely more than 300 m (1000 ft) deep.
That sea, befittingly named Kraken Mare, was the subject of a recent study by lead author Valerio Poggiali from Cornell and his colleagues, as was the not quite so befittingly named Moray Sinus, an estuary at the northern end of the sea. They analyzed data from one of Cassini’s last fly-bys of Titan in August of 2014. That data included radar measurements of Kraken Mare and it’s estuary.
The height from the sea surface to its bottom was calculated using time differentials in those radar signals. Additionally, the percentage of the signal that was rebounded back to Cassini was used to determine a baseline understanding of the sea’s composition.
The radar signal was not actually able to penetrate all the way to the depths of central Kraken Mare, meaning the sea was deeper than the expected 1000 meter range the scientists estimated for the effective distance the radar signal was able to penetrate. Given that the sea is the size of all five Great Lakes combined, it is not particularly surprising the Cassini couldn’t find the bottom of the middle of the sea. However, it was able to reach the depths of Moray Sinus, which was noted at approximately 85 m (280 ft) deep.
In addition, the signal attenuation they found pointed to something unexpected: Kraken Mare is actually made up of more methane than ethane. Scientists had expected ethane to dominate in the sea, largely because of its size and equatorial location. In fact, Kraken Mare’s composition is largely similar to other, smaller lakes in the region, with a methane dominant hydrology.
All of this data analysis and hypothesis development can feed right into the development process of any future submarine mission to one of the Solar System’s largest moons. While there will be many considerations that go into the design of any future mission, it is now clear that no matter what the craft’s size, it will have plenty of room to operate in the alien seas it is designed for.