![]() ![]() “And that energy can create under-ice oceans, maybe even habitable zones. “The same gravity that causes all these weird phenomena that we’re seeing on these little moons causes energy to be pumped into some of the larger ones,” says Terrile. ![]() Understanding Pan and Atlas may be key to understanding gravity’s role in all of Saturn’s moons. “It may also be some kind of gravitational tidal effect from being near all this ring material,” says Terrile. The dominant theory for how the ridges form is that because the moons’ diameters are so much larger than the ring’s thickness, they gather material along their equators as they plow through stray ring particles. The two moons are approximately the same size, but Pan is embedded within a ring, and Atlas is along the outer edge. “What is especially interesting is the extent to which the soft material seems to bury and mute any crisp-looking topographic features even on the central ‘core’ structure,” says Paul Helfenstein at Cornell University in Ithaca, New York, who helped plan the flyby.Īnother moon, Pan, also has an equatorial ridge, but another recent flyby showed its ridge is rough with tension cracks and craters. “It looks like it’s covered in some kind of fluffy material.” “It looks more subdued than I expected,” Terrile says. We already knew Atlas has a UFO-like ridge around its equator, but surprisingly, the new images show that ridge is smooth. “This is a really interesting kind of dynamical dance that these moons do with the ring particles.” But instead, the ring’s shape is held by two other moons, Janus and Epimetheus. The neat ordering of these coplanar worlds (they all lie in the same pancake-like flat plane) strongly suggests they were created from scratch in an original protoplanetary disk, like the genesis. “At the time, we thought the satellite was holding out the edge of the A ring,” Terrile says. But Atlas appears to be a shepherd moon that isn’t responsible for shepherding ring particles. Some of Saturn’s moons, called shepherd moons, use their gravity to keep the planet’s famous rings in check. Saturns moon Atlas got its flat, ravioli-like shape from the merging collision of two similar-size bodies, according to new research. ![]() The imaging operations center is based at the Space Science Institute in Boulder, Colo.įor more information about the Cassini-Huygens mission visit. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. Pan is 33 kilometers (20.5 miles) across at its equator and 21 kilometers (13 miles) across at its poles Atlas is 39 kilometers (24 miles) across at its equator and 18 kilometers (11 miles) across at its poles. The images were acquired with the Cassini spacecraft narrow-angle camera between 20. The ridges represent about 27 percent of Atlas' volume and 10 percent of Pan's volume. The flyby had a close-approach distance of about 7,000 miles (11,000 kilometers). Pan's ridge reaches about 4 kilometers (2.5 miles) at 0 degrees west longitude, and is about 1.5 kilometers (0.9 mile) high over most of the rest of the equator. Saturns moon, Atlas, imaged on April 12, 2017, by NASAs Cassini spacecraft. Heights of Atlas' ridge range from about 3 kilometers (2 miles) at 270 degrees west longitude to 5 kilometers (3 miles) at 180 and 0 degrees. The heights of the ridges can be crudely estimated by assuming (ellipsoidal) shapes that lack ridges and vary smoothly cross the equator. ![]() Atlas shows more asymmetry than Pan in having a more rounded ridge in the leading and sub-Saturn quadrants. On Atlas, the ridge extends 20 to 30 degrees in latitude on either side of the equator on Pan, its latitudinal extent is 15 to 20 degrees. The highest resolution images of Pan and Atlas reveal distinctive "flying saucer" shapes created by prominent equatorial ridges not seen on the other small moons of Saturn.įrom left to right: a view of Atlas' trailing hemisphere, with north up, at a spatial scale of about 1 kilometer (0.6 mile) per pixel Atlas seen at about 250 meters (820 feet) per pixel from mid-southern latitudes, with the sub-Saturn hemisphere at the top and leading hemisphere to the left Pan's trailing hemisphere seen at about 3 kilometers (2 miles) per pixel from low southern latitudes an equatorial view, with Saturn in the background, of Pan's anti-Saturn hemisphere at about 1 kilometer (0.6 mile) per pixel. ![]()
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