Titan is a mystery as powerful as its namesake. A thick haze of atmospheric nitrogen hides the view of the surface of the moon, hiding a strange and ancient geology that scientists have just unmasked.
In a new research, scientists report the discovery of a massive "corridor" of ice-rich rocks that extends around Saturn's largest satellite, stretching for a total of 6,300 kilometers – a length equivalent to 40% of the total of Titans. circumference.
"This icy corridor is intriguing because it does not correlate with any surface features or subsurface measurements," says planetary scientist Caitlin Griffith of the University of Arizona.
Griffith and his team leaned over thousands of spectral images taken by the Cassini spacecraft, using an infrared spectrometer instrument to peer as far as possible through Titan's opaque haze.
With a technique called Principal Component Analysis (PCA) to extract and refine surface features obscured in the data, the team identified the giant ice strangeness over the Titan equator.
"Our PCA study indicates that water ice is uneven, but not randomly, exposed on Titan's tropical surface," the authors write in their paper.
"Most of the exposed ice-rich material follows a long, almost linear corridor that stretches for approximately 6,300 km (30 ° E, 15 ° N) to (110 ° W, 15 ° S)."
What is most unusual about this feature is that it exists, since Titan's surface is largely covered with organic sediments that fall from the breakdown of methane molecules into the atmosphere due to sunlight.
Amidst this strange, moist, gaseous environment, which Griffith characterizes as a "crazed version of Earth," it is not exactly clear how the exposed ice structure fits, so the team thinks it could be a relic from another frozen era in time. .
"It is possible that we are seeing something that is a vestige of an era in which Titan was very different," Griffith said. New scientist.
"It can not be explained by what we see there now."
According to the researchers, the most likely cause could be the legacy of the ancient cryovolcanism: "ice volcanoes" that produce water, ammonia or methane, instead of the rocky magma we know on Earth.
But as Titan currently had no active volcano on the ice, it's still a mystery as to why this giant ice corridor still exists – though that state of affairs does not last much longer, depending on how hard the moon's methane rain keeps falling .
"We detected this feature on steep slopes, but not on all slopes," says Griffith.
"This suggests that the ice corridor is currently eroding, potentially uncovering the presence of ice and organic layers."
The results are reported in Astronomy of Nature.