Titan, Saturn’s largest moon, harbors an ocean of low-density water or ammonia inside, according to an analysis of archival data from NASA’s Cassini mission.
A representation of Cassini’s orbit used to calculate Titan’s gravity. The colored part of the orbit shows the distance from Cassini to Titan, with the minimum distance shown in red. A cross-section of Titan shows the moon’s different layers and blue oceans. In the background you can see Saturn with its rings and ring shadows. Image credit: Britt Griswold, NASA Goddard Space Flight Center.
“Liquid water is one of the prerequisites for life,” said Dr. Sander Goossens of NASA’s Goddard Space Flight Center and colleagues.
“Water is rarely liquid on the surfaces of planets, but many moons of the solar system, such as Titan, have underground oceans.”
“These probably formed a long time ago, which begs the question why they haven’t already frozen in a cold environment far from the sun.”
“Our study supports the explanation that ammonia extended the life of Titan’s liquid oceans. Additionally, it also provides insight into Titan’s deeper layers.”
NASA’s Cassini mission explored Saturn and its icy moons for more than a decade.
Among its many instruments, Cassini carried a radio science subsystem that enabled radiation tracking of Earth-based spacecraft by the Deep Space Network.
These data were used to determine the gravitational field and internal structure of some of Saturn’s moons and Saturn itself. Cassini data was also used to determine Titan’s tidal response.
“The Cassini space probe flew around Saturn from 2005 to 2017,” the researchers said.
“Probes have been sent close to the moon many times to accurately measure Titan’s gravity.”
“Cassini needed to skim past Titan at exactly the right time to properly map the changes in gravity.”
“This is because Titan’s deformation is due to Saturn’s tidal forces, and the tidal forces depend on the distance between Titan and Saturn.”
“Measurements taken when Titan was close to Saturn and when it was far away maximized the difference in Titan’s deformation, and therefore its impact on gravity.”
Scientists calculated Cassini’s speed from precise radar measurements and calculated changes in gravity and the resulting deformation of Titan.
They carefully examined the tidal effects on Titan at each location on the spacecraft’s orbit and concluded that the deformation was smaller than previously calculated.
According to numerical simulations of the moon’s deformation for different internal structures, the most likely scenario is that the ocean has a density similar to water and contains small amounts of ammonia.
“The subsurface ocean may help transport organic matter from the moon’s rocky core to the surface,” the authors said.
“It was thought that Titan’s thick layer of ice between its ocean and its core made this difficult.”
“Our analysis suggests that the ice layer may be thinner than previously thought, and that material exchange between the rock and the ocean is more likely.”
“The organic molecules this produces are considered important ingredients for the emergence of life.”
of study It was published in the magazine natural astronomy.
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S. Goossens other. A low-density ocean inside Titan estimated from Cassini data. Nat Astron, published online March 21, 2024. doi: 10.1038/s41550-024-02253-4
Source: www.sci.news
