NASA’s Cassini spacecraft has returned a new batch of images from Saturn’s moon Titan, revealing previously unseen features on the surface.
The images were taken during Cassini’s 122nd flyby of Titan on July 25 this year, with the spacecraft flying past at a distance of just 976 kilometers (607 miles). Titan’s thick atmosphere obscures the ground from view, but using its Synthetic Aperture radar (SAR) instrument Cassini is able to peer beneath the cloud tops.
In one of the images, we can see long, linear dunes made out of hydrocarbons that have settled out of the atmosphere in a place called Shangri-La. Cassini has found that many of these dunes encircle Titan’s equator, and research back in 2014 suggested they were sculpted by brief rogue winds, rather than constantly shifting like dunes on Earth.
That’s important to note. Titan is an active alien world that is ever-changing, which often leads many to declare it Earth-like – at least in its wind and weather patterns.
“Dunes are dynamic features,” said Jani Radebaugh, a Cassini radar team associate at Brigham Young University in Provo, Utah, in a statement. “They're deflected by obstacles along the downwind path, often making beautiful, undulating patterns.”
The dark streaks are dunes stretching across the surface at Shangri-La, while the bright regions are mountains. NASA/JPL-Caltech/ASI/Universite Paris-Diderot
In another image, Cassini revisited a location called Xanadu. This bright region is about the size of Australia, with its brightness possibly being caused by water-ice. It was first studied by NASA’s Hubble Space Telescope in 1994, and was the first surface feature to be identified on Titan.
Scientists had first thought Xanadu was a raised plateau, but now think the region is actually slightly tilted. This blocks the formation of dunes, which are otherwise found almost everywhere else around the equator.
In this view, Cassini looked at a region near to Xanadu, an annex. Xanadu is relatively unique on Titan in that its mountains are spread over a large area, rather than being small and isolated. Mike Janssen, also from JPL, said the annex had “something different” about it, though, when viewed at other wavelengths with Hubble, although they weren’t sure what this was.
Shown is the mysterious Xanadu annex region. NASA/JPL-Caltech/ASI/Universite Paris-Diderot
Both Xanadu and its annex are some of the oldest regions on Titan, remnants of an icy crust once present. They are supposedly similar to the Badlands in South Dakota, dramatic rock formations left undisturbed through Earth’s history.
The Cassini mission is due to end in September 2017 with a dive into Saturn’s atmosphere, so there are only four more flybys of Titan planned. Excitingly, these will focus on lakes and seas in Titan’s far north region. Hopefully, after Cassini, it won’t be too long until we go back again to learn more about this fascinating world.