Cassini spacecraft spies dunes on Saturn’s moon Titan
Scientists are learning more about the frigid landscape of Saturn’s largest moon, Titan, from recent radar images captured by NASA’s Cassini spacecraft. The images were taken during Cassini’s close flyby of Titan on July 25 when the spacecraft came as close as 607 miles (976 kilometers) from the moon. Cassini’s radar instrument is able to pierce the thick global haze surrounding Titan, revealing fine details on the distant world’s surface.
One of the new images shows long linear dunes, thought to be made up of grains derived from hydrocarbons that have settled out of Titan’s atmosphere. Earlier surveys by Cassini have shown that dunes of this type circle most of Titan’s equator. Researchers can study the dunes to learn about Titan’s winds, the sands that the dunes are composed of, and other features of Titan’s landscape.
“Dunes are dynamic features. They’re deflected by obstacles along the downwind path, often making beautiful, undulating patterns,” said Jani Radebaugh, a Cassini radar team associate at Brigham Young University in Provo, Utah.
Another radar image shows an area that the Cassini radar team has nicknamed “Xanadu annex”. Cassini’s radar has not previously captured images of this area, but earlier measurements by the spacecraft suggested that the terrain might resemble the large region on Titan named Xanadu, which was first imaged in 1994 by NASA’s Hubble Space Telescope. The new image by Cassini shows that the Xanadu annex is made up of the same type of mountainous terrain as Xanadu.
“This ‘annex’ looks quite similar to Xanadu using our radar, but there seems to be something different about the surface there that masks this similarity when observing at other wavelengths, as with Hubble,” said Mike Janssen, also a JPL member of the radar team. “It’s an interesting puzzle.”
Both Xanadu and its annex remain somewhat mysterious. While mountainous terrain on most of Titan appears in small isolated patches, Xanadu covers a wide area. Researchers have suggested a number of theories to explain Xanadu’s formation.
“These mountainous areas appear to be the oldest terrains on Titan, probably remnants of the icy crust before it was covered by organic sediments from the atmosphere,” said Rosaly Lopes, a Cassini radar team member at JPL. “Hiking in these rugged landscapes would likely be similar to hiking in the Badlands of South Dakota.”
The flyby in July was Cassini’s 122nd approach of Titan since the spacecraft arrived at Saturn in 2004. It was also the spacecraft’s final imaging pass over the southernmost regions of Titan.
“If Cassini were orbiting Earth instead of Saturn, this would be like getting our last close view of Australia,” said Stephen Wall, deputy lead of the Cassini radar team at NASA’s Jet Propulsion Laboratory in Pasadena, California.
Cassini’s final four flybys of Titan will focus mostly on the liquid-filled lakes and seas of Titan’s far north. The spacecraft will begin the finale of its mission in April 2017 with a series of 22 orbits that plunge between Saturn and its icy rings.
Video courtesy of NASA/JPL-Caltech
Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.