Saturn’s largest moon, Titan, may harbor a habitable world covered in slimy sea ice, new research suggests.
Back in 2008, NASA’s Cassini spacecraft collected data on Titan that suggested there may be an open ocean beneath the moon’s frozen crust. But researchers say new analysis suggests that what lies beneath is more “muddy tunnels and pockets of snowmelt.”
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“What we’re looking at is not the open ocean like on Earth, but maybe something like sea ice or aquifers in the Arctic, and that has implications for what kind of life we find. [and] Availability of nutrients and energy is also important,” study co-author Baptiste Journeau, an assistant professor of earth and space sciences at the University of Washington, said in a statement.
“Smashing” month
The story begins with the Cassini spacecraft, which was launched in 1997 and spent the better part of two decades observing Saturn and its moons. According to the authors of the new study, Cassini discovered a shape in which Titan is “stretching and squishing” around Saturn. At the time, researchers proposed that if Titan had a deep ocean, Saturn’s gravity would cause its crust to bend.
This new study takes into account the timing of Titan’s bending. The researchers found that Titan’s shape begins to change only about 15 hours after Saturn exerts its strongest gravitational pull on Titan. Scientists then estimated the energy required to change Titan’s shape, which revealed more details about the mysterious moon’s interior.
“No one expected such strong energy dissipation to occur inside Titan,” study lead author Flavio Petricca, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory, said in a statement. “That was conclusive evidence that Titan’s interior was different from what we had inferred from previous analyses.”
Historically, Titans have always been difficult to observe. The planet is covered in a thick orange atmosphere rich in compounds that may be precursors to life. Radar is required to see the surface (Cassini had radar, but previous flyby missions, Voyager 1 and Voyager 2, did not have radar). Cassini’s observations revealed a strange land surface where methane rains down when it rains, oceans are constantly changing, and temperatures hover around -297 degrees Fahrenheit (-183 degrees Celsius).
titanic slash
So what’s going on inside Titan? A new study shows that the moon’s interior appears to have pockets of ice and meltwater beneath its icy exterior, making it an overall slicker environment than thought in 2008. The slush is thick and is likely responsible for the observed delay in Titan’s shape change. Although water is thought to be present in the slush, the researchers found that it would not be as liquid as in the open ocean.
In addition to reusing old Cassini radio observations, the researchers used a new thermodynamic model developed by Journeau’s lab to study how water, minerals, and other components behave on worlds like Titan.
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“Titan’s water layer is so thick and the pressure is so great that it changes the physics of the water,” Journeau said. “Water and ice behave differently than seawater on Earth.”
Expand your life’s explorations
While the lack of a full ocean may initially sound like a blow to the search for life, Jones emphasized that the team actually “expands the range of environments that could be considered habitable.”
Scientists also discovered that there may be “pockets of fresh water” within Titan, where the temperature is 68 degrees Fahrenheit (20 degrees Celsius), which is suitable for life. Moreover, nutrients would be concentrated in this small pool of water, perhaps allowing conditions richer for life than in the ocean, where concentrations are lower.
Future observations may help us understand Titan. NASA’s Dragonfly mission is scheduled to launch as early as 2028 and arrive at Titan in 2034. This will be the second spacecraft to fly on another world other than Earth, following the Mars helicopter Ingenuity. Dragonfly’s observations of Titan’s surface are expected to shed more light on where life is lurking and how much water is available to life.
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