Presence of Atmosphere and Water on Saturn Moon Titan Provides Deeper Understanding on Evolution of Life on Earth

At a symposium presented by the American Chemical Society, "Chemical Frontiers in Solar System Exploration", scientists have gathered to discuss the possibility and the circumstances that could lead to the evolution of life in one of the moons of Saturn, Titan.

Titan is one of the 62 satellites orbiting the planet Saturn. Located around one billion miles away from Earth, it is the only satellite in the solar system that is observed to have an atmosphere. The atmosphere consists of nitrogen and methane and also includes organic compounds such as ethane, acetylene, hydrogen cyanide, and cyanoacetylene.

The circumstances around Titan and its atmosphere closely resembles that of the Earth more than 3.5 billion years ago.

Data about Titan was gathered using the Huygens probe that landed on its surface on January 2005. For 90 minutes after touchdown, the probe transmitted its findings as well as images back to the Earth. The Huygens probe is the farthest landing for any craft launched from the Earth.

Based on the findings, Titan is the only object in the solar system apart from the Earth that contains large amounts of organic substances on the surface.

MIT News: Researchers Analyzing Saturn Moon Titan's River Network

Images from the Cassini mission show river networks draining into lakes in Titan's north polar region.
Image: NASA/JPL/USGS

For many years, Titan’s thick, methane- and nitrogen-rich atmosphere kept astronomers from seeing what lies beneath. Saturn’s largest moon appeared through telescopes as a hazy orange orb, in contrast to other heavily cratered moons in the solar system.

In 2004, the Cassini-Huygens spacecraft — a probe that flies by Titan as it orbits Saturn — penetrated Titan’s haze, providing scientists with their first detailed images of the surface. Radar images revealed an icy terrain carved out over millions of years by rivers of liquid methane, similar to how rivers of water have etched into Earth’s rocky continents.

While images of Titan have revealed its present landscape, very little is known about its geologic past. Now researchers at MIT and the University of Tennessee at Knoxville have analyzed images of Titan’s river networks and determined that in some regions, rivers have created surprisingly little erosion. The researchers say there are two possible explanations: either erosion on Titan is extremely slow, or some other recent phenomena may have wiped out older riverbeds and landforms.

“It’s a surface that should have eroded much more than what we’re seeing, if the river networks have been active for a long time,” says Taylor Perron, the Cecil and Ida Green Assistant Professor of Geology at MIT. “It raises some very interesting questions about what has been happening on Titan in the last billion years.”

A paper detailing the group’s findings will appear in the Journal of Geophysical Research-Planets.

What accounts for a low crater count?

Compared to most moons in our solar system, Titan is relatively smooth, with few craters pockmarking its facade. Titan is around four billion years old, about the same age as the rest of the solar system. But judging by the number of craters, one might estimate that its surface is much younger, between 100 million and one billion years old.

What might explain this moon’s low crater count? Perron says the answer may be similar to what happens on Earth.

“We don’t have many impact craters on Earth,” Perron says. “People flock to them because they’re so few, and one explanation is that Earth’s continents are always eroding or being covered with sediment. That may be the case on Titan, too.”