Titan’s largest sea could reach a depth of 300 meters

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Kraken Mare, a sea of ​​liquid methane found on Titan (the moon of Saturn), would have a depth of at least one hundred meters at the level of the center, according to an analysis of data collected by the Cassini probe in 2014.

With a width of 5,150 kilometers, Titan is the second largest moon in the Solar System, just behind Ganymede. Apart from our planet, it is the only body in the Solar System that has stable liquids on the surface. A billion kilometers from Earth, under its thick golden envelope composed mainly of gaseous nitrogen, a landscape of almost terrestrial appearance looms with rivers, lakes and seas of methane and ethane in liquid form. .

Present in the Saturn system between 2004 and 2017, the Cassini mission had made it possible to estimate the depth and composition of each of Titan’s seas, with the exception of Kraken Mare, the largest which contains about 80% of the moon’s surface liquids. It is now done, at least indirectly.

At least a hundred meters deep

As part of a study recent, Researchers at Cornell University examined data from one of the last overflights of Titan (T104) by the Cassini mission on August 21, 2014. The probe then moved towards just over 900 km above the surface of Titan, spinning at nearly 20,000km / h.

During this overflight, Cassini had deployed his radar altimeter to measure the depth of the liquid (bathymetry) at Kraken Mare and Moray Sinus, an estuary at the northern end of the Great Sea. For the researchers, the idea was basically to Note the differences in radar return time between the liquid surface and the seabed. Its composition could also be estimated by highlighting the amount of radar energy absorbed during transit through the liquid.

This work made it possible to estimate the depth of Moray Sinus: about 85 meters. According to the absorption of radar waves, this estuary would be composed of 70% methane, 16% nitrogen and 14% ethane.

Analysis of elevation data in the main body of Kraken Mare, on the other hand, showed no evidence of signal return from the seabed, suggesting the liquid is either too deep or too absorbent for Cassini’s radio waves. can penetrate. However, assuming that Kraken Mare’s composition is similar to that of Moray Sinus, as one would expect, the researchers estimated that its depth could reach three hundred meters at its center.

This colorized mosaic of the Cassini mission shows a full view of the lakes and seas of northern Titan. Credit: NASA

A submarine on Titan

There would therefore be plenty of room for a potential robotic submarine to explore this gigantic sea, as large as the five Great Lakes combined (approximately 400,000 square kilometers). By the way, that’s good news: researchers are currently working on developing a project in this direction. If approved by NASA, such a mission could be launched in the 2030s with an expected arrival in the 2040s.

Among the scientific equipment possibly on board, the researchers evoke instruments capable of analyzing the chemistry of hydrocarbons, a surface imager, a depth sounder and a weather station. Additional instruments could also analyze seabed samples.

A mission of this type could then teach us more about this incredible moon which, according to many astrobiologists, could shelter life. If indeed it exists, it would be very different from that evolving on Earth.

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