Saturn’s moon Titan has vanishing “magical islands” that may be accumulations of organic matter

(CNN) — Disappearing “magic islands” on Saturn’s largest moon Titan have puzzled scientists ever since NASA’s Cassini mission spotted them during a flyby a decade ago. Now, researchers believe they have uncovered the secrets of this phenomenon.

Although initially thought to be bubbles of bubbling gas, astronomers now believe they may be honeycomb glaciers made of organic material that fell to the moon’s surface.

Scientists consider Titan to be one of the most fascinating moons in our solar system because it shares some similarities with Earth. However, in many ways it also presents a worrying foreign scenario.

Titan, larger than our Moon and the planet Mercury, is the only moon in our solar system with a thick atmosphere. The atmosphere is composed largely of nitrogen and a little methane, which gives Titan its fuzzy orange appearance. According to NASA, Titan’s atmospheric pressure is about 60% greater than Earth’s, so it exerts the kind of pressure that humans feel when floating about 50 feet (15 meters) below the surface of the ocean.

Titan is the only world in our solar system with liquid bodies on its surface, similar to Earth, but rivers, lakes and oceans are composed of liquid ethane and methane, which form clouds and cause rain of the liquid gas. Dear.

The Cassini mission orbiter, carrying the Huygens probe that landed on Titan in 2005, made more than 100 flybys of Titan between 2004 and 2017, allowing scientists to learn a lot about the moon today.

Among the most puzzling aspects of Titan are its magical islands, which scientists have observed as moving bright spots on Titan’s ocean surfaces that may last for a few hours, several weeks, or longer. Cassini radar images captured unexplained bright areas in Ligeia Mare, the second-largest liquid body on Titan’s surface. The sea is 50% larger than Lake Superior and is composed of liquid methane, ethane, and nitrogen.

Astronomers thought that these areas might be clustered bubbles of nitrogen gas, actual islands made of floating solids, or features caused by waves (although the waves reach only a few millimeters in height).

An artist’s illustration shows a lake at the north pole of Saturn’s moon Titan, including the raised edge seen by Cassini.

Planetary scientist Xinting Yu, an assistant professor at the University of Texas at San Antonio, focused on analyzing the relationships between Titan’s atmosphere, liquid bodies, and solids that fall as ice, to see if they form magical islands. May be related.

“I wanted to investigate whether magical islands might actually be organic matter floating on the surface, like pumice that floats in water on Earth before eventually sinking,” said Yu, lead author of a study published Jan. 4 in the journal Geophysical Union. Can swim.” Research Paper.

Scientists’ goal is to understand as much as possible about Titan before sending a specific mission to the moon. The Dragonfly mission, led by the Johns Hopkins Applied Physics Laboratory in collaboration with NASA, is planned to launch in 2028 and reach Titan in the 2030s.

analysis of an unusual world

A variety of organic molecules are present in Titan’s upper atmosphere, such as nitriles, hydrocarbons, and benzene. The surface temperature is so cold (-179 °C) that rivers and lakes were formed by liquid methane, just as rocks and lava helped form landforms and canals on Earth.

Organic molecules in Titan’s atmosphere stick together into clumps before freezing and falling to the moon’s surface. Dark plains and mounds of organic material have been observed on Titan, and scientists believe that these features were largely created by Titan’s “ice.”

But what happens when hydrocarbon ice falls on the strangely smooth surfaces of Titan’s lakes and rivers of liquid gas? Yu and his colleagues examined different scenarios that could occur.

Yu’s team determined that solid organic matter falling from the upper atmosphere would not disintegrate upon landing in Titan’s liquid bodies because they are already saturated with organic particles.

Infrared images taken by an instrument on the Cassini spacecraft provide the clearest view of Titan from beneath its dense haze.

“To look at magical islands, they can’t just float for a second and then sink,” Yu said. “They’ll have to swim for a while, but not forever.”

But liquid ethane and methane have low surface tension, which means it is harder for solids to float on top of them.

Yu’s team simulated various models and determined that frozen solids would not float unless they were porous, like honeycomb or Swiss cheese. Even small particles are unlikely to float on their own unless they are large enough.

The team’s analysis resulted in a scenario in which frozen hydrocarbons solidify near the shore, then break up and float to the surface, much like glaciers on Earth. Liquid methane slowly seeps into frozen cumulus clouds, eventually causing them to disappear from view.

Additionally, according to the researchers, a possible thin layer of frozen solids in Titan’s seas and lakes could explain why the moon’s fluids are so smooth.

approaching titan

Over the next decade, Dragonfly is expected to investigate the plains of organic material in Titan’s equatorial region rather than its liquid bodies.

The helicopter lander will sample materials on Titan’s surface, study the potential habitability of its unique atmosphere, and determine what chemical processes are occurring on the moon.

Organic chemicals essential for life on Earth, such as nitrogen, oxygen and other carbon-based molecules, are also found on Titan. Beneath Titan’s thick layer of ice lies an internal ocean of salt water, not unlike those of other fascinating moons of sea worlds orbiting Saturn, such as Enceladus or Jupiter’s moon Europa, which are most likely to be searched for life. Considered one of the good places. beyond the earth.

According to NASA, Titan appears to be inhospitable, but it is possible that conditions there could be favorable for life based on different chemistry and shapes that are beyond our current understanding.

This story was published on January 12, 2024 and has been updated