Scientists have found several possible explanations for the temporal features found on Saturn’s largest moon. But a new study points to a theory that may be the most likely cause: Titan's seas are bubbling with nitrogen.
Back in 2013, a bright mysterious feature of the moon suddenly appeared in pictures taken by the Cassini radar apparatus. A strange anomaly, which was not observed in the previous images, inexplicably arose in the Sea of Liegei - the second largest, located near the north pole.
During the next flight in a few days, the feature informally baptized by the “magic island” disappeared. And then next year two similar anomalies were discovered.
Scientists have proposed several explanations for what is happening, but new data point to a theory that may be the most likely cause: the seas of Titan bubble with nitrogen, creating island-like formations.
The sea of the frozen moon does not consist of water. Titanium is so cold (-290 ° F or -179 ° C) that it can contain only seas of liquid hydrocarbons, such as methane and ethane. The combined missions of Cassini and Huygens determined that it was cold liquid methane rain falling from the sky that accumulates in rivers, lakes and seas. But how could “islands” form in such an environment? A recent experiment by scientists of the Jet Propulsion Laboratory simulated the conditions on Titan. He showed that even minor transformations in temperature, air pressure or composition can lead to the rapid release of nitrogen from a solution, resembling a bubbling fountain that occurs when a bottle of champagne or a can of cola is opened.
“When fluids rich in methane are mixed with strong ethane rain, or when methane runoff rivers encounter ethane lake, nitrogen is less likely to remain in solution,” said Michael Malaska of JPL, who is at the head.
“The main idea is that many bubbles (or other phenomena) would give a signal of the same type as solid earth,” added Malaska. - “The radar will be reflected from the bubbles and display a similar signature.”
This is an infrared view of the moon of Saturn Titan, observed from a NASA Cassini spacecraft. It was captured during the flight of “T-114” on November 13, 2015.
Research has shown that a significant amount of nitrogen can be released when hydrocarbons are mixed, as well as when the temperature changes. The air (exsolution - separation) caused by bubbles could create quite large features that fell under the scope of Cassini’s tools. “Significant amounts of nitrogen gas will be released from Titan’s lake liquids when heated and also absorbed when cooled,” the team wrote in its article published in Icarus magazine. “The density of lake liquids will depend on the dissolution of nitrogen. The model also shows that mixing two cryogenic fluids of different composition can lead to the release of large amounts of nitrogen gas, which is important for lake fluids, bubble formations and geological phenomena. ”
“After examining the solubility of nitrogen, we were convinced that bubbles could actually form in the seas and could be more numerous than we expected,” says Jason Hofgartner of JPL, a co-researcher from the Cassini radar team and co-author of the study.
NASA noted that such a carbonated liquid could also create problems for any potential future flights to Titan, especially for spacecraft that could sail or sail through the seas of Titan. Excessive heat generated by the apparatus, can start the process of formation of bubbles around its parts. For example, this may affect propellers used for movement, making it difficult to control or maintain the stability of the probe.
Cassini’s mission will end in September. When the probe approached Saturn, the team received amazing views of the moons and rings of the planet. A closer orbit also allows you to do more research on Titan, and get new pictures of the features of the moon.
Twitter by Carolyn Porco: “Cassini’s new orbits make it easier to see through Titan’s mist. Voila ... of the sea and the lake of liquid methane. "
Some of the lakes on Titan are as big as the Great Lakes in the US or the Caspian Sea, located between Europe and Asia. Cassini even caught the sunlight flashing from one of the lakes, with hints of waves in other lakes.
Cassini will make its last close flight to Titan (127th maneuver) on April 22. The spacecraft for the last time will conduct a radar beam over the northern seas of Titan. The team has planned the forthcoming observation, so that if this time magical island features are found, their brightness can be useful for identifying bubbles, waves, and floating or static solids.
Cassini begins the final series of 22 dives through the gap between Saturn and the inner rings - the Grand Finale of Cassini.
The 15-year mission will end with a test dive into the atmosphere of Saturn on September 15.