NASA’s Cassini spacecraft captures high-resolution images of Saturn’s icy moon Enceladus during its 14 October flyby. The earlier Voyager mission suggested a heavily cratered north pole, but the new images by Cassini reveal a landscape of stark contrasts.
The Daily Mail reports:
Taken by the Cassini spacecraft as it made its 14 October flyby, the images show the northern regions are covered in cracks that slice through the craters on one side, while the other side appears much smoother.
Nasa captured the best ever views of the northern extremes of Saturn’s icy, ocean-bearing moon as it travelled 1,142 miles (1,839km) above the lunar surface
The first image shows the curvature of the moon and the pockmarks created by the craters. A second image zooms in closer to this surface to show the cracks that tear through these craters.
One large crack resembles a river running through the centre of this northern region.
Cracks have similarly been spotted in the surface of our own moon and this has been blamed on the gravitational pull of Earth tearing its surface apart.
In fact, Nasa scientists have identified more than 3,200 cracks, each several miles long and dozens of feet deep, crisscrossing our moon’s surface that resemble those spotted on Enceladus.
A second image zooms in closer to this surface to show the cracks (pictured) that tear through these craters. The long crack in this image resembles a river running through the centre of this northern region. Cracks have similarly been spotted in the surface of our own moon and this has been blamed on the gravitational pull of Earth tearing its surface apart
‘The northern regions are crisscrossed by a spidery network of gossamer-thin cracks that slice through the craters,’ said Paul Helfenstein, a member of the Cassini imaging team at Cornell University, New York.
‘These thin cracks are ubiquitous on Enceladus, and now we see that they extend across the northern terrains as well.’
In another image, Cassini spied a tight trio of craters as it made its approach to the icy moon.
The craters, located at high northern latitudes, are sliced through by thin fractures that form part of the network of similar cracks that wrap around the moon.
Nasa has dubbed the trio of craters ‘Saturnian snowman’ because of its shape.
That particular image was taken in visible light using a narrow-angle camera at a distance of approximately 6,000 miles (10,000 km) from Enceladus.
To give an indication of the size of the 310-mile (500km) wide moon, the image scale is 197ft (60 metres) per pixel.
Enceladus is Saturn’s sixth-largest moon – one of 62 – discovered in 1789 by William Herschel.
In the early 1980s Nasa sent two Voyager spacecraft to the Saturnian system to capture the first close-up images of the moon.
Voyager 1 made its flyby on 12 November 1980 but captured only poor resolution shots that revealed a highly reflective surface that didn’t appear to have any craters on it.
Voyager 2 made its closest approach on 26 August 1981 during which its higher-resolution images instead revealed the surface to be heavily cratered in the north and lightly cratered around the equator.
Nasa’s Cassini craft began multiple flybys of Enceladus in 2005 and was able to identify cryovolcanoes near the south pole that shoot geyser-like jets of water vapour.
Last month, these geysers were said to be evidence of a large ocean beneath Enceladus’ surface.
Nasa said the fine spray of water vapour, icy particles and simple organic molecules Cassini had observed coming from fractures near the moon’s south pole are fed by a vast liquid water reservoir.
This also explains why the moon has a very slight wobble as it orbits Saturn.
Without a solid core, the moon travels slightly faster and slower during different portions of its orbit which causes it to rock back and forth.
This is enhanced by the fact Enceladus isn’t a perfect sphere.
Images released last month also revealed that Enceladus is slowly being eaten up by its host planet’s giant’s rings.
These images showed how long, sinuous, tendril-like structures near Enceladus are transferring material from the moon into Saturn’s rings.
These ghostly tendrils have long been known to follow Enceladus in its orbit around the gas giant and the images provided scientists with the first opportunity to track their source.
The tendrils reach into Saturn’s E ring – the ring in which Enceladus orbits – extending tens of thousands of miles away from the moon.
Cassini’s next encounter with Enceladus is planned for 28 October when the spacecraft will come within 30 miles (49km) of the moon’s south polar region.
During the encounter, Cassini will make its deepest-ever dive through the moon’s plume of icy spray to sample the chemistry of the extraterrestrial ocean beneath the ice.
Mission scientists said they are hopeful data from that flyby will provide evidence of how much hydrothermal activity is occurring in the moon’s ocean, along with more detailed insights about the ocean’s chemistry – both of which relate to the potential for Enceladus to host life.
Cassini will then make its final close Enceladus flyby on 19 December when the spacecraft will measure the amount of heat coming from the moon’s interior. That flyby will be at an altitude of 3,106 miles (4,999km).
The Cassini-Huygens mission is a cooperative project between Nasa, Esa and the Italian Space Agency.