New research has found that most waves on Titan’s seas of liquid hydrocarbons are diminutive, reaching only about 1 cm (0.4 inches) high and 20 cm (8 inches) long — a finding that indicates a serene environment that could be good news for future robotic lander missions to Saturn’s hazy moon. The results are published in the journal Earth and Planetary Science Letters.
An artist’s rendering of the surface of Saturn’s largest moon, Titan. Image credit: Benjamin de Bivort, debivort.org / CC BY-SA 3.0.
Titan is the largest moon of Saturn and one of the locations in the Solar System that is thought to possess the ingredients for life.
In photos taken by NASA’s Cassini spacecraft, it appears as a smooth brown orb because of its thick atmosphere clouded with gaseous nitrogen and hydrocarbons.
However, radar images from Cassini show that it has a surface crust made of water ice and drenched in liquid hydrocarbons.
On Titan, methane and ethane fall from the sky as rain, fill deep seas and lakes, and are possibly spewed into the air by icy volcanoes called cryovolcanoes.
“The atmosphere of Titan is very complex, and it does synthesize complex organic molecules — the bricks of life,” said lead author Dr. Cyril Grima, a research associate at the Institute for Geophysics at the University of Texas at Austin.
“It may act as a laboratory of sorts, where you can see how basic molecules can be transformed into more complex molecules that could eventually lead to life.”
“On top of that, it’s also thought to have an ocean of liquid water beneath its icy crust.”
Titan’s three largest lakes — Kraken Mare, Ligeia Mare and Punga Mare — and their surrounding areas as seen by Cassini’s RADAR instrument. Image credit: Cyril Grima, University of Texas at Austin.
By analyzing data collected by Cassini’s RADAR instrument during Titan’s early summer season, Dr. Grima and co-authors found that waves across the three largest lakes in Titan’s northern hemisphere — Kraken Mare, Ligeia Mare and Punga Mare — reach only about 1 cm high (0.4 inches) and 20 cm (8 inches) long.
“There’s a lot of interest in one day sending probes to the seas, and when that’s done, you want to have a safe landing, and you don’t want a lot of wind,” Dr. Grima said.
“Our study shows that because the waves aren’t very high, the winds are likely low.”
“This work is an independent measure of sea roughness and helps to constrain the size and nature of any wind waves,” said co-author Dr. Alex Hayes, an assistant professor of astronomy at Cornell University.
“From the results, it looks like we are right near the threshold for wave generation, where patches of the sea are smooth and patches are rough.”
“Our results call into question the early summer’s classification as the beginning of the Titan’s windy season, because high winds probably would have made for larger waves,” Dr. Grima added.
Information on Titan’s climate is essential for sending a probe safely to the surface.
“Although there are no formal plans for a mission, there are plenty of concepts being developed by researchers around the world,” Dr. Grima said.
“The study indicates that if a future mission lands in early summer, there’s a good chance that it is in for a smooth landing.”
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Cyril Grima et al. 2017. Surface roughness of Titan’s hydrocarbon seas. Earth and Planetary Science Letters 474: 20-24; doi: 10.1016/j.epsl.2017.06.007
