Liquid organic molecules on Earth are solid, icy minerals on Saturn’s moon Titan

Titan, Saturn’s largest moon, has revealed some of its mysteries: Two organic molecules that occur in liquid form on our planet are solid minerals on the icy satellite. The data will be used in the mission that NASA will launch in 2027 to Titan.

A group of researchers has laboratory recreated the conditions of Titan, Saturn’s moon, in small glass cylinders. According to a press release, the study reveals the fundamental properties of two organic molecules believed to exist as minerals on Titan.

Scientists discovered, for example, that simple organic molecules that are liquid on Earth are typically solid, icy mineral crystals on Titan, due to their extremely low temperatures. The research results were presented at the last meeting of the American Chemical Society (ACS).

Titan is the largest of Saturn’s satellites and also the second largest in the entire Solar System. So far, it is the only satellite in which a significant and rich atmosphere has been discovered. Composed mainly of ice and rocky material, its dense and opaque atmosphere prevented understanding of its surface until the arrival of the Cassini-Huygens mission in 2004.

A strange and frozen world
It is now known that Titan has lakes of liquid hydrocarbons in the polar regions, and that its atmosphere is composed mainly of nitrogen, while up to 6% can be methane and complex hydrocarbon compounds. It has geographical features similar to those of the Earth, such as rivers, dunes, deltas and seas, which would be made up of liquid methane and ethane. Its climate is dominated by seasonal patterns as on our planet.

It is the only known body in space, other than Earth, where clear evidence of stable pools of surface liquid has been found. Furthermore, being powered by energy from the Sun, Saturn’s magnetic field, and cosmic rays, both nitrogen and methane present in its atmosphere react on Titan to produce organic molecules of various sizes and complexities.

Molecules as minerals
Specifically, the researchers argue that acetonitrile (ACN) and propionitrile (PCN) molecules are present in Titan’s characteristic yellow haze, appearing as aerosols. They fall as a dense rain on the surface, depositing as solid pieces of minerals and crystallizing.

Although the characteristics of these molecules are widely known on Earth, it had not been discovered so far how they would react in a context like that of Titan. In the laboratory, the scientists reproduced the conditions of the atmospheric rain that distributes the molecules on Saturn’s moon, to later replicate the temperature changes that occur on Titan.

The new research would not only reveal aspects related to this satellite, but also questions about the general structure of planetary ice that were previously unknown. For example, changes in temperature on Titan would cause the thermal expansion of the crystals that make up the molecules to be uneven in all directions, causing the moon’s surface to crack. This characteristic of Titan could be repeated in other icy worlds.

The data obtained will provide information for researchers working on an upcoming NASA mission to Titan, due to launch in 2027. Saturn’s satellite is especially attractive to scientists in terms of the possibilities it offers to study the origins of life. in the cosmos, especially after the information provided by the Cassini-Huygens mission between 1997 and 2017, focused on Saturn and its moons.