The above images and image to the left are the views of Enceladus as the Cassini spacecraft drew closer and closer on Thursday, July 14, 2005. By the time Cassini had passed the small moon it had come to within 172 km (107 miles) of the surface, the closest flyby yet in a 4-year mission to tour and collect data about the Saturnian system.
Enceladus, a tiny moon of Saturn, may be a world of water ice volcanoes actively resurfacing the surrounding terrain, according to planetary scientists. Surprised by tantalizing evidence of activity, scientists believe Enceladus may be the primary source of material for one of Saturn’s rings.
Data from Titan has shown that water ice in the outer solar system is as hard as rock and plays a role similar to the silicates that make up the rocky bodies of the inner solar system. A gravitational tug-and-pull between Enceladus and another Saturnian moon, Mimas, may provide enough energy to partially melt portions of its inner mantle or core, providing a ready supply of material to erupt onto the surface and out into space. The possible presence of ammonia in that water may act as antifreeze to create “molten” water.
The Cassini spacecraft was commanded to fly by Enceladus on Thursday, July 14, 2005 much closer than originally planned. The flyby distance was only 172 km (107 miles) compared to 1,000 km (622 miles) to provide the highest resolution images ever of this ice world. Cassini will not fly by Enceladus again until March 12, 2008.
The Cassini mission team is currently processing the data and the first images are beginning to show up in the “Raw Images” database on the website. The image above was taken when Cassini was approximately 207,529 kilometers away from Enceladus. Scientists will look at images that include resolutions as small as 40 meters per pixel to try to determine if the moon is currently active. The surface map to the right illustrates the regions that were to be covered by Cassini’s cameras and the expected resolution. The south pole of Enceladus was to have been imaged for the first time. Check back with The Frontier Channel from time to time over the next few days for the latest news about the Enceladus flyby.
As if Titan was not exciting enough, the Cassini space probe recently detected an atmosphere around a second Saturnian moon, this time Enceladus. Cassini did not spot the atmosphere directly but discovered that Saturn’s magnetic field lines are being bent in the vicinity of Enceladus. This indicates diversion of the field by an atmosphere.
Because the moon is too tiny (according to NASA it would fit inside the state of Arizona) to hold an atmosphere for long, the atmosphere must be dynamically sustained. Scientists believe that this discovery is related to current tectonic activity on the moon. Much of Enceladus’ surface is young and the snow white brightness of the planet also implies recent resurfacing. Theories include active ice volcanoes and geysers and/or plate tectonics that bring pristine materials from the moon’s interior to the surface. If confirmed, the Saturnian system may prove to be much more dynamic than previously conceived.
The background image is Enceladus in false-color to bring out some of the surface composition differences. The faded gray behind Enceladus is a portion of Saturn (giving a hint at just how massive the planet really is compared to a tiny fleck of dust like Enceladus). The foreground image is an artist’s concept of the atmosphere’s affect on Saturn’s magnetic field.
On March 09, 2005 the Cassini space probe flew by Enceladus, capturing new images of the bright white moon of Saturn. The lack of craters in some regions and intense fracturing suggest past tectonic activity and resurfacing, though neither activity has been confirmed yet.
While scientists try to figure out what they are seeing in the returned images, Cassini is heading for two more flybys of Titan on March 31 and April 16, 2005. Cassini will return to Enceladus on July 14, 2005.
In a little over a week, Cassini will pass within 1,179 km of another Saturn moon, Enceladus. Images already returned have revealed a young water ice surface lacking craters. The wrinkles and ridges in the image are tantalizing indicators of recent geological activity on the small (499 km in diameter) moon.
The Cassini spacecraft orbiting Saturn has returned first images of many of the planet’s moons. This first orbit will be Cassini’s longest, as Saturn and its moons are used to shrink the orbit down to something more science activity-friendly. In 89 days the spacecraft will make a close flyby of Titan.
On its way out, Cassini took the closest images of Titan ever captured. While visual light images depicted the same smog-covered moon, other frequencies of light were used to take images of the surface. Mysteries abound. The predicted lakes or seas of methane were not seen. Instead, the images revealed a diverse surface possibly modified by different geological processes as well as bright methane clouds hovering near the south pole. When Cassini comes around for another pass it will be much closer, allowing much clearer images.
The images of the other moons reveal little more than Voyager images from the 1980s. Future orbits of Cassini will target specific moons, giving each its own moment in the spotlight.