Saturn’s moon Titan may not have a buried ocean: study
Saturn’s giant moon Titan may not have a large underground ocean after all.
Titan may instead hold deep layers of ice and slush that resemble Earth’s polar seas, along with pockets of meltwater where life could possibly survive and even thrive, scientists said Wednesday.
A team led by researchers at NASA’s Jet Propulsion Laboratory challenged the decade-old assumption of a buried global ocean on Titan after taking a new look at observations made years ago by NASA’s Cassini spacecraft around Saturn.
They emphasize that no one has found any signs of life on Titan, the solar system’s second largest moon at 5,150 kilometers across and filled with lakes of liquid methane on its icy surface.
However, Baptiste Journaux from the University of Washington, who participated in the study published in the journal Nature, stated that the latest findings point to a watery, almost melting environment and said, “There is a strong reason to continue optimism about the potential for extraterrestrial life.”
He said in an email that “nature has shown far greater creativity than the most creative scientists” regarding what kind of life form this might be (possibly strictly microscopic).
Lead author Flavio Petricca of JPL said Titan’s ocean may have been frozen in the past and is now melting, or its hydrosphere may be evolving toward complete freezing.
Computer models suggest that these layers of ice, slush and water extend to depths of more than 550 kilometers.
The outer ice shell is thought to be about 170 kilometers deep, covering layers of puddles and sleet that could extend down another 400 kilometres.
This water can be as hot as 20C.
Because Titan is tidally locked, the same side of the moon always faces Saturn, just like our own moon and Earth.
Saturn’s gravitational pull is so intense that it deforms the moon’s surface, creating protrusions as high as 10 meters when the two objects are closest to each other.
Thanks to improved data processing, Petricca and his team were able to measure the timing between the peak of gravity and the rise of Titan’s surface.
Petricca said the effect would be immediate if the moon had a wet ocean, but a 15-hour gap was detected, suggesting an interior of watery ice with pockets of liquid water.
Computer modeling of Titan’s orientation in space supported their theory.
Luciano Iess of the Sapienza University of Rome, whose previous work using Cassini data had pointed to a hidden ocean on Titan, was not convinced by the latest findings.
“While it will certainly be interesting and stimulate new discussions… the currently available evidence certainly does not appear to be sufficient to exclude Titan from the family of oceanic worlds,” Iess said in an email.
NASA’s Dragonfly mission, which includes a helicopter-type craft scheduled to launch to Titan later this decade, is expected to provide greater clarity about the moon’s interior.
