A team of scientists led by Sebastian Rodriguez, an astronomer at the University of Paris Diderot in France, has obtained impressive results while studying material from the Cassini space probe. Earth bears another striking resemblance to Titan, the moon of Saturn, according to new research – in addition to geology and the carbon cycle, scientists have identified an active dust cycle in which organic dust can be lifted from large dune fields around Titan's equator. This was reported on the official NASA website.
Titan is an incredibly intriguing world. In fact, it is the only satellite in the solar system that has an atmosphere like Earth and the only celestial body that has liquid reserves on the surface. However, there is one big difference: on Earth, such rivers, lakes and seas are filled with water, and on Titan it is methane. and ethane. In such a unique cycle, hydrocarbon molecules evaporate, condense into clouds and rain back to the surface.
The weather on Titan varies from season to season, just like on Earth. Particularly during the equinox (the time when the Sun crosses Titan's equator) massive clouds can form in tropical regions and cause violent methane storms. The Cassini probe observed such storms during its flight past the satellite.
A collection of images from the spacecraft's flyby past Titan in 2009 and 2010 shows three instances of clear bright spots suddenly appearing in images taken by the spacecraft's visual and infrared imaging spectroscope.
When Rodriguez and his team first noticed three unusual equatorial hues in infrared images taken by Cassini during the northern equinox on Titan in 2009, they thought they were some kind of methane cloud, but further research showed that it was something completely different.
“From what we know about cloud formation on Titan, we can say that such methane clouds are physically impossible in this area at this time of year,” Rodriguez said. “Convective methane clouds that can develop in this area and during this time period will contain huge droplets and should be at very high altitudes – much higher than 10 kilometers, as our models indicate.”
In addition, scientists have found that these features on the surface of Titan could not be in the form of cold methane rain or icy lava. Such surface spots would have different chemical constituents and would remain visible much longer than the bright formations, which were visible from as little as 11 hours for five weeks.
In addition, modeling showed that the characteristics should be atmospheric, but still close to the surface – that is, most likely, it is a very thin layer of fine solid organic particles. Moreover, they were located directly above the dunes at the equator of Titan, so the only remaining explanation was that the spots were actually clouds of dust raised from the dunes.
Organic dust is formed when organic molecules formed by the interaction of sunlight with methane grow to a large enough size and fall to the surface. According to Rodriguez, they managed to observe the first storm on Titan and this is a natural process.
“We believe that the Huygens probe, which landed on Titan's surface in January 2005, raised a small amount of organic dust upon arrival due to its powerful aerodynamic wake,” Rodriguez said. “But what we noticed here in our analysis of the Cassini data is happening on a much broader scale. The near-surface wind speeds required to kick up as much dust as we see in these dust storms must be very strong – about five times stronger than the average wind speeds measured by the Huygens probe.
Edition and translation: Kolupaev Dmitry
