Saturn’s moon Titan is the only place other than Earth with known bodies of liquid on its surface. A new study paints a startling different view of those lakes and seas to our world, with tiny waves rippling across them.
Published in the journal Earth and Planetary Science Letters, researchers led by the University of Texas found that waves on Titan would reach a height of only about 1 centimeter (0.4 inches). They would also extend for little more than 20 centimeters (7.9 inches).
The discovery was made using radar data from the Cassini spacecraft. The study’s lead author, Cyril Grima, developed a technique that can measure “surface roughness” in really, really fine detail. Fine enough to measure the waves as being no more than 1.5 to 2.5 centimeters (0.6 to 1 inch) in height. Grima told IFLScience the wind speeds were estimated at 0.22 meters (0.72 feet) per second at 10 meters (33 feet) above the surface.
This research looked at three lakes in Titan’s northern hemisphere: Kraken Mare (Titan’s largest lake), Ligeia Mare, and Punga Mare. The final flyby of Titan by Cassini in April studied this region, and data from this may soon tell us how deep these lakes are.
The implication of this is that the wind speeds on Titan likely aren’t that high. This means that if we ever want to land a probe in one of the seas – which has been discussed – then wind might not be too much of a problem. As Titan’s winds are currently low and the moon is currently in its “summer”, this also casts doubt on the idea that summer is the windiest season on Titan.
"There's a lot of interest in one day sending probes to the lakes, and when that's done, you want to have a safe landing, and you don't want a lot of wind," Grima said in a statement. "Our study shows that because the waves aren't very high, the winds are likely low."
Bodies of liquid on Titan are not like those on Earth. While ours are made of water, on Titan they are composed of liquid hydrocarbons, basically the ingredients for jet fuel. Like Earth, though, these liquids go through a cycle of evaporation and rain, although each location on Titan only sees rain roughly once every 1,000 years.
Back in 2005, we sent our first ever lander to Titan: ESA’s Huygens probe. This returned stunning images of the ground, but since then our appetite has been whetted for more. NASA has been toying with the idea of sending a boat-like probe there for some time, which may be done at some point in the future.
It should be noted that the small height of Titan’s waves has been mooted before, but this study lends further evidence to the theory. They move at a rather sedate 0.7 meters (2.3 feet) per second too, so probably too slow (and low) for surfing. But hey, at least we can probably send a boat there.
There are still quite a lot of unknowns, notes Grima. But this study at least tells us a bit more about what Titan might be like.
"The windy season could start later in the summer than expected, but it is also possible that the windy season is not constant in time or space," he told IFLScience. "We cannot rule out that smaller patches of higher waves, not sustained over a long period of time, might exist. Future research on climate models will have to explain which is right."