For the first time, a canyon network flooded with liquid hydrocarbons has been detected by NASA's Cassini spacecraft on the surface of Saturn's moon Titan, the space agency revealed Wednesday.
The discovery represents the first direct evidence of the presence of liquid-filled channels on Titan, indicating diverse and complex geologic activity similar to what we have on our planet, researchers said.
NASA astronomers analyzed data gathered by Cassini from a close flyby that occurred in May 2013. During this event, the spacecraft's radar instruments focused on channels that branch out from Ligeia Mare, a large northern sea on the Saturn moon.
Observations reveal that these channels, particularly a network called Vid Flumina, are actually narrow canyons less than half a mile wide, with slopes steeper than 40 degrees.
The narrow canyons are also deep. Some canyons measured 790 feet (240 meters) to 1,870 feet (570 meters) from top to bottom, scientists said.
For comparison, the depth of the Vid Flumina canyon network on Titan is less than a third of the depth of the Grand Canyon. The Titan canyon network is only a small fraction of the Grand Canyon's width.
In radar images, the branching channels appear dark, much like the methane-rich seas on the Saturn moon. This has led scientists to believe that the channels might also contain liquid.
However, for a while, it has not been clear whether the dark material was actually liquid or just saturated sediment, which would be made of ice and not rock thanks to frigid temperatures on Titan. Direct detection of the material has not been made until now.
In the new research, scientists used Cassini's radar as an altimeter that sent pings of radio waves to the surface of Titan, measuring the height of its features. The data gathered were then combined with past radar images.
In the end, researchers discovered that Titan's canyon system is indeed filled with channels of flowing liquid from abundant lakes, seas and rains.
One key to understanding the nature of Titan's channels was the way the radar signal from Cassini reflected off the bottom of the features on the Saturn moon.
The radar instrument noticed a glint, suggesting an extremely smooth surface similar to that on the moon's hydrocarbon seas.
As the radar signal echoed and bounced off the canyon floors and edges, researchers were able to get a direct measure of the depths.
What Created The Canyons?
The presence of such depth in the landscape indicates that whatever process created them eroded down much faster than other regions on the surface.
Valerio Poggiali, the study's lead author and a team associate of the Cassini radar team, says it is likely that a combination of changes in sea level and uplift of the terrain contributed to the formation of the flooded canyons.
These are actually processes that occur on Earth. Alex Hayes, the study's co-author, explains that Titan and Earth are two completely different worlds: the former is icy and cold with rivers of methane, while the latter is rocky and warm with rivers of water.
"[Yet] it's remarkable that we find such similar features on both worlds," says Hayes.
However, to what degree these factors influenced the formation is still not clear, Poggiali says. What is evident is that any description of the Saturn moon's geological evolution has to corroborate with the findings and explain how the canyons formed.
The findings of the new study are issued in the journal Geophysical Research Letters.