NASA | JPL-Caltech | Cassini | 2019 Sep 09
Using radar data from NASA's Cassini spacecraft, recently published research presents a new scenario to explain why some methane-filled lakes on Saturn's moon Titan are surrounded by steep rims that reach hundreds of feet high. The models suggests that explosions of warming nitrogen created basins in the moon's crust.
Titan is the only planetary body in our solar system other than Earth known to have stable liquid on its surface. But instead of water raining down from clouds and filling lakes and seas as on Earth, on Titan it's methane and ethane — hydrocarbons that we think of as gases but that behave as liquids in Titan's frigid climate.
Most existing models that lay out the origin of Titan's lakes show liquid methane dissolving the moon's bedrock of ice and solid organic compounds, carving reservoirs that fill with the liquid. This may be the origin of a type of lake on Titan that has sharp boundaries. On Earth, bodies of water that formed similarly, by dissolving surrounding limestone, are known as karstic lakes.
The new, alternative models for some of the smaller lakes (tens of miles across) turns that theory upside down: It proposes pockets of liquid nitrogen in Titan's crust warmed, turning into explosive gas that blew out craters, which then filled with liquid methane. The new theory explains why some of the smaller lakes near Titan's north pole, like Winnipeg Lacus, appear in radar imaging to have very steep rims that tower above sea level — rims difficult to explain with the karstic model. ...
Explosive Nitrogen Created Craters that Pock Saturn Moon Titan
Cornell University | 2019 Sep 09
Possible explosion crater origin of small lake basins with raised rims on Titan ~ Giuseppe Mitri et al
- Nature Geoscience (online 09 Sep 2019) DOI: 10.1038/s41561-019-0429-0