Cassini Images of Titan Reveal an Active, Earth-like World

Mar 09, 2005
Cassini Images of Titan Reveal an Active, Earth-like World

Saturn's largest and hazy moon, Titan, has a surface shaped largely by Earth-like processes of tectonics, erosion, winds, and perhaps volcanism. The findings are published in this week's issue of the journal Nature.
Titan, long held to be a frozen analog of early Earth, has liquid methane on its cold surface, unlike the water found on our home planet. Among the new discoveries is what may be a long river, roughly 1,500 kilometers long (930 miles). Scientists have also concluded that winds on Titan blow a lot faster than the moon rotates, a fact long predicted but never confirmed until now.

Tectonism (brittle fracturing and faulting) has clearly played a role in shaping Titan's surface. "The only known planetary process that creates large-scale linear boundaries is tectonism, in which internal processes cause portions of the crust to fracture and sometimes move either up, down or sideways," said Dr. Alfred McEwen, Cassini imaging team member from the University of Arizona, Tucson. "Erosion by fluids may accentuate the tectonic fabric by depositing dark materials in low areas and enlarging fractures. This interplay between internal forces and fluid erosion is very Earth-like."

Cassini images collected during close flybys of the moon show dark, curving and linear patterns in various regions on Titan, but mostly concentrated near the south pole. Some extend up to 1,500 kilometers (930 miles) long. Images from the European Space Agency's Huygens probe show clear evidence for small channels a few kilometers long, probably cut by liquid methane. Cassini imaging scientists suggest that the dark, curved and linear patterns seen in the Cassini orbiter images of Titan may also be channels, though there is no direct evidence for the presence of fluids. If these features are channels, it would make the ones near the south pole nearly as long as the Snake River, which originates in Wyoming and flows across four states.

Since most of the cloud activity observed on Titan by Cassini has occurred over the south pole, scientists believe this may be where the cycle of methane rain, channel carving, runoff, and evaporation is most active, a hypothesis that could explain the presence of the extensive channel-like features seen in this region. In analyzing clouds of Titan's lower atmosphere, scientists have concluded that the winds on Titan blow faster than the moon rotates, a phenomenon called super-rotation. In contrast, the jet streams of Earth blow slower than the rotation rate of our planet.

"Models of Titan's atmosphere have indicated that it should super-rotate just like the atmosphere of Venus, but until now there have been no direct wind measurements to test the prediction," said Cassini imaging team member Dr. Tony Del Genio of NASA's Goddard Institute for Space Studies, in New York. DelGenio made the first computer simulation predicting Titan super-rotation a decade ago.

Titan's winds are measured by watching its clouds move. Clouds are rare on Titan, and those that can be tracked are often too small and faint to be seen from Earth. Ten clouds have been tracked by Cassini, giving wind speeds as high as 34 meters per second (about 75 miles per hour) to the east -- hurricane strength -- in Titan's lower atmosphere. "This result is consistent with the predictions of Titan weather models, and it suggests that we now understand the basic features of how meteorology works on slowly rotating planets," said Del Genio.

"We've only just begun exploring the surface of Titan, but what's struck me the most so far is the variety of the surface patterns that we're seeing. The surface is very complex, and shows evidence for so many different modification processes," said Dr. Elizabeth Turtle, Cassini imaging team associate in the Lunar and Planetary Laboratory at the University of Arizona, Tucson and co-author of one of the papers in Nature.

"Throughout the solar system, we find examples of solid bodies that show tremendous geologic variation across their surfaces. One hemisphere often can bear little resemblance to the other," said Dr. Carolyn Porco, Cassini imaging team leader, Space Science Institute, Boulder, Colo. "On Titan, it's very likely to be this and more."

These results are based on Cassini orbiter images of Titan collected over the last eight months during a distant flyby of the south pole and three close encounters of Titan's equatorial region. Cassini cameras have covered 30 percent of Titan's surface, imaging features as small as 1 to 10 kilometers (0.6 to 6 miles). Cassini is scheduled to make 41 additional close Titan flybys in the next three years.

Source: NASA

Explore further: Cosmic rays threaten future deep-space astronaut missions

add to favorites email to friend print save as pdf

Related Stories

Cyanide ice in Titan's atmosphere

Oct 01, 2014

Gigantic polar clouds of hydrogen cyanide roughly four times the area of the UK are part of the impressive atmospheric diversity of Titan, the largest moon of Saturn, a new study led by Leiden Observatory, ...

Cassini watches mysterious feature evolve in Titan sea

Sep 29, 2014

(Phys.org) —NASA's Cassini spacecraft is monitoring the evolution of a mysterious feature in a large hydrocarbon sea on Saturn's moon Titan. The feature covers an area of about 100 square miles (260 square ...

Ten years of Cassini

Sep 09, 2014

Ten years ago, the Cassini-Huygens mission entered the Saturnian System and in January 2005, the Huygens probe landed softly on the surface of Saturn's largest moon, Titan. These historic events, which revolutionized ...

Recommended for you

Cosmic rays threaten future deep-space astronaut missions

56 minutes ago

Crewed missions to Mars remain an essential goal for NASA, but scientists are only now beginning to understand and characterize the radiation hazards that could make such ventures risky, concludes a new paper ...

Big black holes can block new stars

3 hours ago

Massive black holes spewing out radio-frequency-emitting particles at near-light speed can block formation of new stars in aging galaxies, a study has found.

MAVEN studies passing comet and its effects

3 hours ago

NASA's newest orbiter at Mars, MAVEN, took precautions to avoid harm from a dust-spewing comet that flew near Mars today and is studying the flyby's effects on the Red Planet's atmosphere.

POLARBEAR seeks cosmic answers in microwave polarization

3 hours ago

An international team of physicists has measured a subtle characteristic in the polarization of the cosmic microwave background radiation that will allow them to map the large-scale structure of the universe, ...

How to safely enjoy the October 23 partial solar eclipse

3 hours ago

2014 – a year rich in eclipses. The Moon dutifully slid into Earth's shadow in April and October gifting us with two total lunars. Now it's the Sun's turn. This Thursday October 23 skywatchers across much ...

User comments : 0