One of the newest raw images from Cassini’s latest flyby shows the icy terrain of Saturn’s moon Dione, with steep hills, ridges and the bright face of one of the many deep canyons that meander across its surface. Known as “wispy lines”, these canyon walls expose bright water ice (that makes up about a quarter of the 700-mile-wide moon) since darker surface coatings can’t stick to their steep cliff sides. The most reflective deposits appear white in the image above, which I have level-adjusted to enhance detail.
Based on the original image scale of 50 feet per pixel (the Cassini spacecraft was about 1600 miles above Dione when this was taken…that’s about 7 times the max altitude of the ISS) the canyon wall is over a mile high! Standing on the edge would be like standing on the rim of the Grand Canyon…except that the sky would be filled with Saturn! Cool.
It’s been suggested that the canyons on Dione are a mature stage of the “tiger stripe” features found on nearby Enceladus, which are the source of ice geysers that supply material to the diffuse E-ring that ultimately ends up coating the surface of Dione. The Saturnian family is a very interconnected one.
See more images of Dione from the April 7th flyby as well as some bonus ones of Janus, Epimetheus and Enceladus on the Cassini imaging lab site here.
Image: NASA/JPL/Space Science Institute