The Mysteries Of Titan's Surface Deepen

A strikingly bright feature that is consistent with an active geology has been seen in one of Cassini's first radar images of Saturn's moon Titan. There are many possibilities for what it is but one of the leading candidates is that it may be a 'cryovolcanic' flow or 'ice volcano'.

"It may be something that flowed," said Cassini radar team member Dr. Ralph Lorenz of the University of Arizona, Tucson. "Or it could be something carved by erosion. It's too early to say.

"But it looks very much like it's something that oozed across the surface. It may be some sort of cryovolcanic flow, an analog to volcanism on Earth that is not molten rock but, at Titan's very cold temperatures, molten ice."

Cassini's radar mapped about one percent of Titan's surface during the spacecraft's first close Titan flyby on Oct. 26. The radar survey covered a strip 120 kilometers (75 miles) wide and 1,960 kilometers (1,200 miles) long in Titan's northern hemisphere.

Cassini was flying about 2,494 (1,550 miles) above Titan's surface, with its radar centered at about 45 degrees north, 30 degrees west, when it mapped the 230-square-kilometer (90-square-mile) area shown in the new radar image. The Cassini radar team presented the image yesterday at the 36th annual meeting of the American Astronomical Society’s Division for Planetary Sciences in Louisville (KY).

The radar instrument on board Cassini works by bouncing radio signals off Titan's surface and timing their return. The more signal reflected back to the spacecraft, the brighter the imaged area. Turning radio signals into radar images is time consuming because so many numerical calculations must be made. "There's no such thing as a 'raw' radar image," said Lorenz.

Just two days after the Oct. 26 flyby, Cassini scientists knew that Titan is not a crater-pocked dead world, but a much more interesting place. Titan's surface is young. It might have been altered by ongoing dynamic geologic processes that cover and obscure old impact craters. Lorenz, and Cassini interdisciplinary scientist Dr. Jonathan Lunine also of the University of Arizona, and other Cassini scientists, agree in this interpretation.

Given this newest image, Lunine said, "Cassini's radar has provided the first evidence for possible young cryovolcanism on Titan's surface. Now our challenge is to find out what is flowing, how it works, and the implications for Titan's evolution."

FMI: http://saturn.jpl.nasa.gov, www.nasa.gov/cassini