These polar maps show the first global, topographic mapping of Saturn's moon Titan, using data from NASA's Cassini mission. To create these maps, scientists used a mathematical process called splining, which uses smooth curved surfaces to "join" the areas between grids of existing topography profiles obtained by Cassini's radar instrument. Image: NASA/JPL-Caltech/ASI/JHUAPL/Cornell/Weizmann
Scientists have pieced together the first-ever global topographic map of Titan, Saturn's largest moon, using radar observations from veteran NASA spacecraft.
The new map of Titan was stitched together from radar observations of the moon by NASA's Cassini spacecraft. It reveals an unprecedented look at Titan's surface and should help scientists learn more about one of the most Earth-like bodies in the solar system, members of the mapping team said.
"Titan has so much interesting activity — like flowing liquids and moving sand dunes — but to understand these processes it's useful to know how the terrain slopes," Ralph Lorenz, a member of the Cassini spacecraft's radar team at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., who led the map design effort, said in a statement. "It's especially helpful to those studying hydrology and modeling Titan's climate and weather, who need to know whether there is high ground or low ground driving their models."
Titan is the second largest moon in the solar system, and the only one known to have clouds and a dense atmosphere. Scientists have been keen to study the cloud-covered world because of its Earth-like qualities. Titan's atmosphere, like Earth, is primarily composed of nitrogen, but instead of water, Titan's rain, clouds and lakes are made of methane.
Titan's nitrogen-rich atmosphere also contains organic chemicals that are derived from methane, which may hold clues to the building blocks of life as we know it, the researchers said.
Seeing through the clouds
Typically, NASA maps the topography of planetary bodies using remote cameras to observe the shapes and shadows of the landscape. Titan's thick atmosphere, however, makes this difficult, the researchers explained.
NASA's Cassini probe has flown by Titan nearly 100 times since it arrived at Saturn in 2004. As the spacecraft swings past the hazy moon, it uses a radar imager to pierce through the clouds. These radar measurements can then be used to estimate the heights of topographical features on the moon.
But, since Cassini is only able to observe Titan on flybys, putting together a complete map of its surface is challenging.
"We have only imaged about half of Titan's surface, and multiple 'looks' or special observations are needed to estimate the surface heights," Lorenz said. "If you divided Titan into 1-degree by 1-degree [latitude and longitude] squares, only 11 percent of those squares have topography data in them."