Cassini's confirmation that a small moonlet orbits within the Keeler gap in Saturn's rings is made all the more exciting by this image, in which the disk of the 7 kilometer- (4 mile-) wide body is resolved for the first time.
The new body, provisionally named S/2005 S1, was first seen in a time-lapse sequence of images taken on May 1, 2005 as Cassini began its climb to higher elevations in orbit around Saturn (see PIA06238 for the discovery movie). This view was acquired one day after the discovery sequence of images and has allowed scientists to measure the moon's size and brightness.
In the vicinity of the moonlet, the Keeler gap edges bear striking similarities to the scalloped edges of the 322 kilometer- (200 mile-) wide Encke gap, where the small moon Pan (28 kilometers, 17 miles across) resides. From the size of the waves seen in the scalloped edges of the Encke gap, imaging scientists were able to estimate the mass of Pan. They expect to do the same eventually with S/2005 S1.
This image was obtained with the narrow angle camera on May 2, 2005 from a distance of about 594,000 kilometers (369,000 miles) from Saturn. Cassini was about 525,000 kilometers (326,000 miles) above the ringplane when the image was taken. Resolution in the original image was 3 kilometers (2 miles) per pixel. The image has been magnified by a factor of two, and contrast has been enhanced, to aid visibility of the small moonlet.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.