Scientists have recreated conditions on Titan, Saturn’s moon, in small glass cylinders. They identified the fundamental properties of two organic molecules that the researchers believe exist as minerals on Titan.
Titan, Saturn’s largest moon, is a natural laboratory for studying the origin of life. Like Earth, Titan has a dense atmosphere and seasonal weather cycles, but the chemical and mineralogical composition is significantly different. Scientists recently recreated conditions on Titan in a laboratory. They identified the fundamental properties of two organic molecules that the researchers believe exist as minerals on Titan.
Simple organic molecules, which are liquid on Earth, look like solid ice mineral crystals on Titan. The reason is low temperatures – down to −178°C. During the experiment, the scientists discovered that two molecules that are likely to be abundant on Titan – acetonitrile (ACN) and propionitrile (PCN) – are predominantly in the same crystalline form. It creates highly polar nanosurfaces that can serve as templates for the self-assembly of other molecules.
Through the Cassini mission, scientists have learned that Titan is a great place to study the origins of life. Like Earth, Titan has a dense atmosphere, but it is mostly nitrogen with an admixture of methane. It is the only known body in space other than Earth, where scientists have found clear evidence of stable pools of surface fluid. Fueled by solar energy, Saturn’s magnetic field and cosmic rays, nitrogen and methane react on Titan to form organic molecules of varying sizes and complexity. ACN and PCN are believed to be present in the Moon’s characteristic yellow haze as aerosols, and they fall to the surface, settling as hard lumps of minerals.
The properties of these molecules on Earth are well known, but their characteristics under conditions like Titan have not yet been studied. “In the laboratory, we recreated the conditions on Titan in tiny glass cylinders,” says Tomche Runczewski, Ph.D., the project’s principal investigator. “In the experiment, we used nitrogen, as well as ACN and PCN to simulate precipitation.” The researchers then raise and lower the temperature slightly to simulate temperature fluctuations on the lunar surface.
The crystals formed were analyzed using synchrotron and neutron diffraction equipment, spectroscopic experiments, and calorimetric measurements. “We have learned a lot about the previously unknown structures of planetary ice. For example, we found that a single crystalline form of PCN does not expand uniformly in three dimensions. Knowing these minerals in detail will help you better understand what Titan’s surface looks like, ”concludes Runchevski.