Enormous 'Puzzling' Ice Corridor That Wraps Halfway Around Saturn's Moon Titan Discovered

A huge ice corridor has been discovered on Saturn's biggest moon, Titan. The icy streak was found to stretch approximately 40 percent of the circumference of the moon—making it over 4,000 miles in length.

"This icy corridor is puzzling, because it doesn't correlate with any surface features nor measurements of the subsurface," Caitlin Griffith, lead author of the study about the discovery, said in a statement.

Titan is the only object in the solar system other than Earth that is known to have liquid rain. But unlike our home planet, on Titan the rain is methane, which fills the huge lakes that exist on the moon's surface.

The source of methane on Titan is unclear, however. It is thought some of it comes from evaporation at the polar lakes, but this does not account for most of what scientists observe.

Finding out where the methane comes from is challenging because Titan's surface is shrouded by the moon's thick atmosphere. That changed, however, when NASA's Cassini spacecraft visited Saturn and its planets. Over the mission, Cassini performed multiple flybys of Titan, using various measurements—including radar and infrared instruments—to peer through, giving scientists a glimpse of this unusual moon.

Previously, it had been suggested that reservoirs beneath the moon's surface could be supplying the methane, with vents pumping it into the atmosphere—a process potentially driven by volcanism.

Griffith, from the University of Arizona, and her team, were looking for 'cryovolcanoes' by analyzing images from Cassini. Their method allowed them to look at weak surface features that could be caused by ice and organic sediments. This is when they came across the ice corridor—findings of which were published in Nature Astronomy.

"Titan's global ice feature presents a puzzle," they wrote. "Ice-rich terrains in other areas of Titan occur only in local regions excavated by craters or exposed by erosion, suggesting that cryovolcanism, if active, is currently not widespread."

Researchers say the presence of the ice corridor raises the question of whether tectonic processes were involved in its formation—however more research will be needed to understand this unusual feature.

"Given that our study and past work indicate that Titan is currently not volcanically active, the trace of the corridor is likely a vestige of the past," Griffith said. "We detect this feature on steep slopes, but not on all slopes. This suggests that the icy corridor is currently eroding, potentially unveiling presence of ice and organic strata."

Andrew Coates, a professor of physics at the University College London, who was not involved in the research, commented on the findings. He said the researchers use a powerful analysis technique to uncover this "unexpected, remarkably long, ice-rich corridor."

"This strange corridor is not understood yet, as it does not correspond with observed surface features, but it might be the sign of cryovolcanic activity in the past," he told Newsweek. "Although there are signs of past cryovolcanism elsewhere in smaller features, it is thought that currently such activity is rare at most, but some mechanism must be providing communication between the interior and surface of Titan, and replenishing the methane in the atmosphere. Clearly there is much more to do to understand this jewel in the outer solar system.