Giant dust storms on Saturn’s moon Titan discovered for first time

NASA’s Cassini spacecraft has helped astronomer’s spot giant dust storms on Saturn’s moon Titan for the first time. The discovery makes Titan the third Solar System body after Earth and Mars where scientists have observed dust storms.

Astronomers believe that the latest observation will help them better understand the environment of Saturn’s largest moon. The discovery was described in a paper published in the journal Nature Geoscience on Sept. 24.

Titan is the only celestial body other than Earth to house stable bodies of surface liquid. But unlike our planet where rivers, lakes and seas are filled with water, it’s methane and ethane that flows through Titan’s liquid reservoirs.

While examining infrared images taken by Cassini around Titan’s 2009 northern equinox, astronomers spotted “three unusual equatorial brightening.” They initially thought them to be methane clouds. But subsequent investigation revealed that the brightening were something completely different.

This animation, based on images captured by the Visual and Infrared Mapping Spectrometer (VIMS) on NASA’s Cassini mission during several Titan flybys in 2009 and 2010, shows clear bright spots that have been interpreted as evidence of dust storms.
Image credits: NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018

“From what we know about cloud formation on Titan, we can say that such methane clouds in this area and in this time of the year are not physically possible,” Sebastien Rodriguez, an astronomer at the University Paris Diderot, France, and the paper’s lead author, said in a statement.

“The convective methane clouds that can develop in this area and during this period of time would contain huge droplets and must be at a very high altitude — much higher than the 6 miles (10 kilometers) that modeling tells us the new features are located,” Rodriguez added.

This compilation of images from nine Cassini flybys of Titan in 2009 and 2010 captures three instances when clear bright spots suddenly appeared in images taken by the spacecraft’s Visual and Infrared Mapping Spectrometer.
Credits: NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018

In addition, the researchers could make two more significant observations. First, the detected features were not on the surface of Titan in the form of frozen methane rain or icy lavas. Second, the features must be atmospheric but still close to the surface, likely forming a very thin layer of tiny solid organic particles.

The features were located right over the dune fields around Titan’s equator. Therefore, the only remaining explanation for researchers was that the features were actually dust clouds raised from the dunes.

According to scientists, these giant dust storms might have been generated by strong winds. This also suggests that the underlying sand can be set in motion, and that Titan’s equatorial regions house giant dunes that are active and continually changing.

“We already know that about its (Titan’s) geology and exotic hydrocarbon cycle. Now we can add another analogy with Earth and Mars: the active dust cycle, in which organic dust can be raised from large dune fields around Titan’s equator,” Rodriguez said.

Featured image courtesy: NASA/ESA/IPGP/Labex UnivEarthS/University Paris Diderot

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