2024-10-28 09:45:00
Titan, the largest moon of the planet Saturn, is the only star other than Earth to have an atmosphere and liquids in the form of rivers, lakes and seas on its surface. Due to its extremely cold temperature, Titan’s liquids are made of hydrocarbons such as methane and ethane, and the surface is largely made up of water ice.
The analysis of observations of Titan carried out by NASA space probes that traveled to the Saturn system has revealed the existence of a great mystery: the impact craters on Titan are hundreds of meters shallower than expected and on this moon they are Only 90 craters were identified, an insignificant amount compared to the number of craters on other comparable stars.
In a recent study, researchers analyzed the puzzle and found a possible explanation.
The study is the work of a team led by Lauren R. Schurmeier, of the Institute of Geophysics and Planetology at the University of Hawaii in the American city of Manoa.
The scarcity of craters and their depth leave scientists baffled. Based on the characteristics and abundance of craters on Saturn’s other moons, we expected to see many more impact craters on Titan’s surface and at much greater depths than the few craters observed on that satellite. “We realized that something unique about Titan must have caused them to become shallower and disappear relatively quickly,” Schurmeier explains.
To investigate what might lie behind this mystery, Schurmeier and his colleagues tested in a digital model how Titan’s topography might react after an impact if the ice crust was equipped with a layer rich in methane clathrate, a kind of of water ice with trapped methane. within the crystalline structure.
Methane clathrate is stronger and more insulating than ordinary water ice. This means that any internal heat on Titan, coming from deep underground, is retained much better underground than if the crust were made exclusively of normal water ice.
Because the initial shape of Titan’s craters is unknown, the researchers modeled and compared two plausible initial depths, based on interesting-looking, similarly sized craters on a similarly sized icy moon, Ganymede.
Using this modeling method, they were able to narrow the thickness of the methane clathrate crust to between five and ten kilometers, as simulations performed at that thickness produced crater depths that better matched the observed craters.
Titan seen using VIMS, a visible-light and infrared mapping spectrograph aboard NASA’s Cassini space probe. Near the center you can see an impact crater. The dark areas near the equator are dunes of organic-rich sand, while the dark areas in the north polar region are lakes of liquid methane and ethane. White clouds are also seen in the Northern Hemisphere. (Photo: NASA/Cassini VIMS)
The methane clathrate crust keeps Titan’s interior warm and ductile and causes surprisingly rapid topographic relaxation, resulting in crater depth decreasing at a rate similar to that of Earth’s fast-moving glaciers.
All this and the existence of convection generate a more favorable scenario for the detection of life, if there is any on that star. Specifically, this scenario would make it easier to transport biomarkers to the surface or not far below it, where they would be much more accessible for extraction by robotic systems from spacecraft landing there.
With NASA’s Dragonfly mission to Titan, scheduled to launch in July 2028 and arrive in 2034, there will be a good opportunity to take a closer look at this moon and further investigate its icy surface, including a crater called Selk.
The study is titled “Rapid impact crater relaxation caused by an insulating methane clathrate crust on Titan.” And it was published in the academic journal The Planetary Science Journal. (Fountain: NCYT by Amazings)
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