Titan, Saturn’s largest moon and the only known celestial body other than Earth to have liquids on its surface, has been studied extensively by planetary scientists. Their analysis suggests that beneath the moon’s icy surface, which is about 297 degrees Fahrenheit cooler, lies a vast ocean.
A new, more in-depth analysis published in Nature however, suggested that Titan’s deep “oceans” might actually be dense layers of hydrocarbon sludge.
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The mystery of Saturn’s Moon
Researchers first proposed that Titan might have oceans based on an analysis by NASA. Cassini mission to Saturn, which first reached the gas giant in 2004. But the probe’s data did not match some of the other physical data Cassini recorded.
Titan’s lemon-shaped orbit around Saturn causes the Moon to stretch and squeeze depending on where it is in its journey. Researchers believe such drastic physical changes could only be made possible by a vast ocean.
“The degree of deformation depends on Titan’s interior structure. A deep ocean would allow the crust to flex more under Saturn’s gravitational pull, but if Titan were entirely frozen, it would not deform as much,” Baptiste Journaux, a University of Washington planetary scientist and co-author of the study, explained in a press release.
The new study added an additional measurement – time – to previous studies of how Saturn modifies its moon. The team noted that instead of warping when the gas giant’s gravity was strongest, Titan shifted about 15 hours later. This, they realized, could be due to viscosity.
While a wading pool filled with water can be moved with relative ease – by a cannonball from an overenthusiastic adult, for example – the same swimming pool filled with jelly would require much more energy to move. Likewise, researchers realized that the delay was due to Titan’s thicker consistency, requiring more energy to move.
By calculating this energy, the team was able to decipher what Titan’s interior was likely to be made of. The global ocean theory did not fit the data.
“The smoking gun” behind Titan’s interior
“Instead of an open ocean like we have here on Earth, we’re probably looking at something like sea ice or Arctic aquifers, which has implications for the kind of life we might find, but also the availability of nutrients, energy, etc.,” Journals said.
This consistency would still explain why Titan can crash under Saturn’s gravity, but would also explain the delay. “No one expected very strong energy dissipation inside Titan. This is compelling evidence that Titan’s interior is different from what had been inferred from previous analyses,” NASA planetary scientist Flavio Petricca, also a co-author of the study, said in a press release.
In the study, Petricca analyzed the timing of radio waves emitted by Cassini during Titan flybys. Journals confirmed his colleague’s suspicions by simulating how ice and water might react deep in Titan’s oceans.
“The water layer on Titan is so thick, the pressure is so immense, that the physics of water changes. Water and ice behave differently than seawater here on Earth,” Journals said.
If Titan’s seas aren’t as watery as first thought, could that hurt the Moon’s chances of containing life? The authors argue that the opposite might be true. If much of the planet’s water is actually melting snow, the remaining areas that are water will likely be much warmer, reaching up to 68 degrees Fahrenheit. These more favorable conditions could be associated with richer, more nutrient-rich waters, which could also increase the likelihood of life forming.
“The discovery of a melting snow layer on Titan also has exciting implications for the search for life beyond our solar system,” study author and planetary scientist Ula Jones said in a press release. “This expands the range of environments we could consider habitable.”
Learn more: Icy moons orbiting Saturn and Uranus could hide boiling liquid oceans
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