Peaks on a Saturn moon like Earth's, BYU scientist says

A Brigham Young University planetary scientist has discovered that mountains on a distant moon of Saturn are surprisingly earthlike.

Jani Radebaugh, associate professor of geology at the Provo university, is part of the team examining radar and other images from the Cassini spacecraft orbiting Saturn. A fascinating part of Cassini's job is studying the smog-covered moon Titan, the second-largest moon in the solar system and the only one with a heavy atmosphere.

The moon is so hazy that some of the best views of the surface are made with radar, which penetrates the atmosphere and beams back views much like optical images. Radebaugh is part of the Cassini team studying these radar and light views of Titan.

In the December issue of Icarus, "the international journal of solar system studies," she is the lead author of an article "Mountains on Titan Observed by Cassini Radar."

Radar images of Titan's surface show that blocks of material have mountainous features, the article says. Although not as large as many of Earth's mountains, they have peaks, valleys and ridges like our planet's — features formed by erosion that are not like mountains known anywhere else in the solar system.

Soon after earning her doctorate at the University of Arizona, Radebaugh approached two members of the Cassini radar team at that university, Jonathan I. Lunine and Ralph D. Lorenz, "and asked if either of them needed anyone to work with them," she said in a telephone interview.

They set her to work on analyzing radar data from Cassini that indicated the presence of mountains and dunes. She was able to begin studying images as they came in when Cassini had swept pass Titan.

The huge moon's dense atmosphere has about the same pressure at the surface as Earth's. That atmosphere makes it difficult to analyze mountain shapes through optical photos. Sunlight is diffused through the clouds, leaving few shadows that otherwise could give clues to mountain shapes and sizes. "Also, Titan is 10 times as far away from the sun as the Earth is," she said.

The dim sunlight and thick haze make the surface "kind of like a dark, cloudy day on the Earth, when you don't have shadows cast." One instrument, however, takes photos in the near-infrared, and it did provide some images of mountains with shadows, which helped to verify the radar team's findings.

Titan's distance from the sun makes the moon extremely cold, with temperatures on the range of minus 290 degrees Fahrenheit. Water ice is frozen as solid as rock, and the gases methane and ethane are liquid.