Cassini spies Titan's methane-flooded canyons
Deep channels filled with liquid hydrocarbons etch the surface of the Saturnian moon.
NASA's Cassini spacecraft has found deep, steep-sided canyons on Saturn's moon Titan that are flooded with liquid methane.
It's first direct evidence of the presence of liquid-filled channels on Titan along with the canyons hundreds of metres deep.
A paper in the journal Geophysical Research Letters describes how scientists analysed Cassini data from a close pass the spacecraft made over Titan in May 2013.
During the flyby, Cassini's radar instrument focused on channels that branch from the large, northern sea Ligeia Mare.
The Cassini observations reveal that the channels – in particular, a network named Vid Flumina – are narrow canyons, generally a little less than a kilometre wide, with slopes steeper than 40 degrees.
The canyons are 240 to 570 metres deep. They appear dark in radar images, much like Titan's methane-rich seas.
This suggested to scientists that the channels might also be filled with liquid, but a direct detection had not been made until now.
Previously it wasn't clear if the dark material was liquid or merely saturated sediment – which at Titan's frigid temperatures would be icy, not rocky.
TITAN CAN HELP RESEARCHERS TEASE APART CONDITIONS iN EARTH's youth, WHICH IS THE ONLY OTHER BODY IN THE SOLAR SYSTEM WITH A SURFACE ACTIVELY ERODING ON A LARGE SCALE
Cassini's radar is often used as a camera of sorts, providing a window to peer through the dense haze that surrounds Titan to reveal the surface below.
But during this pass, the radar was used as an altimeter, sending pings of radio waves to the moon's surface to measure the height its features.
The timing of the radar echoes bouncing off the canyons' edges and floors gave the Cassini team a direct measure of their depths.
The researchers combined the altimetry data with previous radar images of the region to make their discovery and proposed scenarios for the deep cuts, such as terrain uplift and changes in sea level – or perhaps both.
"It's likely that a combination of these forces contributed to the formation of the deep canyons, but at present it's not clear to what degree each was involved," says Valerio Poggiali of the University of Rome and lead author of the study.
"What is clear is that any description of Titan's geological evolution needs to be able to explain how the canyons got there."
Studying the geologic processes on Titan can help researchers tease apart the Saturnian moon’s origins as well as conditions in Earth's youth, which is the only other body in the solar system with a surface actively eroding on a large scale.
Titan allows scientists to see how these processes change under varying conditions, such temperature changes.