Saturn’s Moon Titan Has Disappeared “Magic Islands” That May Be Accumulations of Organic Matter

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

Although initially thought to be bubbles of superfluid gas, astronomers now believe they may be honeycomb glaciers formed by organic matter falling onto the moon’s surface.

Scientists consider Titan to be one of the most attractive moons in our solar system because it shares some similarities with Earth. However, in many ways it also presents a disturbingly alien landscape.

Titan, larger than our moon and the planet Mercury, is the only moon in our solar system with a dense atmosphere. The atmosphere is composed mostly of nitrogen with some methane, which gives Titan its faint orange appearance. Titan’s atmospheric pressure is about 60% greater than Earth’s, so it exerts the kind of pressure humans experience when swimming about 50 feet (15 meters) below sea level, according to NASA.

Titan is also the only other world in our solar system that has liquid matter on its surface similar to Earth, but the rivers, lakes, and oceans are composed of liquid ethane and methane, which form clouds and precipitate liquid gases. darling

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 to reveal much of what scientists know about the moon today.

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

Astronomers theorized that these regions could be clustered bubbles of nitrogen gas, actual islands made of floating solids, or features attributed to waves (although the waves reach heights of only a few millimeters).

An artist’s rendering shows a lake at the north pole of Saturn’s moon Titan, including the high ridges observed by Cassini.

Planetary scientist Xingting Yu, an assistant professor at the University of Texas at San Antonio, focused on analyzing the connections between Titan’s atmosphere, liquids, and solids falling as ice to see if they are related to magical islands.

“I wanted to investigate whether the magic islands could actually be organic matter floating on the surface, such as pumice, that can float in water on Earth before eventually sinking,” said Yu, lead author of the study published Jan. 4 in the journal Geophysical Union. Research papers.

Scientists aim to understand as much as possible about Titan before sending specific missions 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.

Analyzing an unusual world

A variety of organic molecules exist in Titan’s upper atmosphere, such as nitriles, hydrocarbons, and benzene. Surface temperatures are so cold (-179 degrees Celsius) that rivers and lakes were carved by liquid methane, just as rocks and lava helped form landforms and canals on Earth.

Organic molecules in Titan’s atmosphere stick together in 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 the features were largely created by Titan’s “ices.”

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

The Uni team determined that solid organic material falling from the upper atmosphere would not dissolve after landing in Titan’s liquid mass because it is already saturated with organic particles.

Infrared images captured by instruments on the Cassini spacecraft provide the clearest view of Titan from beneath its dense haze.

“For us to see magical islands, they don’t just float for a second and then sink,” Yu said. “They have to float for a while, but not forever.”

But liquid ethane and methane have low surface tension, which means solids have a hard time floating on top of them.

The Uni team simulated various models and determined that solid solid materials 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 coast, then break up and float across the surface, similar to glaciers on Earth. Liquid methane slowly enters frozen cumulus clouds, causing them to disappear from view.

In addition, according to the researchers, a possible thin layer of frozen solids in Titan’s oceans and lakes could explain why the moon’s liquids are so smooth.

Approaching Titan

Over the next decade, Dragonfly is expected to probe fields of organic matter 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 taking place 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 crust is an icy, saltwater interior ocean, not unlike other fascinating moons of ocean worlds orbiting Saturn, such as Enceladus or Jupiter’s moon Europa, which are considered some of the best places to look for life. beyond the earth.

Titan seems obscure, but it’s possible that it has conditions conducive to life based on different chemistry and shapes that are beyond our current understanding, according to NASA.