Titan is a puzzle wrapped in mystery.
Well, actually, it's wrapped in a dense atmosphere, but nonetheless, Titan's surface is a riddle only now beginning to be understood, thanks to a lot of new data coming in from the Cassini spacecraft and the Huygens probe dropped on the moon from Cassini in 2005.
Two papers published this month involving UA researchers have drawn new conclusions about this enigmatic aspect of the outer solar system.
Titan has a "horrendously thick atmosphere," about 1.5 times the pressure of Earth, said Robert Brown of the Lunar and Planetary Laboratory at the UA and co-author of one of the papers.
Titan is the largest moon of Saturn, larger even than the planet Mercury, which is why it is able to retain an atmosphere when such moons as Earth's cannot.
People are also reading…
This atmosphere, mainly nitrogen but with clouds of liquid methane, has a high-altitude haze remarkably similar to the smog of big cities.
"We never really know what we're going to be looking at," said Jonathan Lunine, another professor at the Lunar and Planetary Lab and lead author of a separate paper about Titan published this month. "It's always a surprise."
Both papers were published in the planetary sciences journal Icarus. Lunine's paper is about the data from two passes made recently by Cassini over Titan using radar, which is able to give very high resolution of the surface of Titan.
The two passes mentioned in the paper revealed very different types of terrain.
One area appears to have channels carved into the surface by liquid methane or ethane Lunine said. The channels "look pretty recent," and it is possible that the liquid is still there, although that fact cannot be determined with radar.
In comparison, the other area is covered with structures like sand dunes, though made up of organic solids rather than silicates like sand dunes on Earth.
These organics are considered "the intermediate building blocks leading to life," Brown said.
The dunes and the area between the dunes were the subject of Brown's recent paper.
Brown's research used data from the Visual and Infrared Mapping Spectrometer on Cassini, which though not as high-definition as radar, gives information that is "directly indicative of what the material is made of," Brown said.
The data used are "the first observations of the dunes not in radar," Brown said.
Titan is considered to be about 60 percent rock and 40 percent water-ice, and the crust appears to be mainly water-ice covered by the organics that make up the dunes, Brown said.
There is evidence that liquid water seas exist underneath the ice crust.
So far, about 30 percent of Titan has been covered by radar resolution in Cassini's exploration of the Saturnian system.
About 40 percent of the surface will be observed with radar by the end of the mission, leading to a better understanding of the diverse features of the moon.
"It's not a homogeneous world," Lunine said.
Saturn facts
• Saturn is about 10 times as far away from the sun as Earth is.
• It takes light (including transmissions from Cassini) 84 minutes to get to Earth from Saturn.
• Saturn has a volume 755 times that of Earth but is less dense than water.
To learn more
Northwest Tucson's Uptown project lands 2 restaurants, tasting room
