Cassini continues to uncover new wonders within the Saturn system with its discovery of two new moons orbiting between Mimas and Enceladus.
These two movies show the tiny worldlets, temporarily dubbed S/2004 S1 and S/2004 S2, as they make their way around the planet. A white box frames each moon's location in each image. The images, which are part of a sequence specifically designed to search for new moons in the inner Saturnian system, have not been cleaned of artifacts but have been greatly enhanced in contrast to increase visibility. Consequently, the background scattered light from the nearby rings, as well as many cosmic ray hits and noise patterns, are clearly apparent.
The sizes of S/2004 S1 and S/2004 S2 have been estimated to be 3 and 4 kilometers (about 2 and 2.5 miles) across, respectively. Because they are small, the moons are not resolved and appear as faint points of light just barely visible above the background.
The images were taken on June 1, 2004 from a distance of 16.5 million kilometers (10.3 million miles) from Saturn. The image scale is approximately 100 kilometers (62 miles) per pixel. The views were taken looking upward from Cassiniís southern vantage point beneath the ring plane.
The S1 movie spans about 90 degrees of the moonís orbit around the left side of the planet and consists of 27 frames taken over a period of precisely six hours. The S2 movie consists of two segments: The first covers about 10 degrees of the moonís orbit around Saturn on the left side of the planet, followed by an 80-degree gap, and then another approximately 30 degrees of revolution on the right side. The S2 movie consists of 28 frames which were acquired over a period of nine and one-quarter hours. The overexposed object seen orbiting Saturn in the S2 movie is Enceladus; Mimas is seen in the S1 movie.
S/2004 S1 orbits at a distance of approximately 194,000 kilometers (120,000 miles) from Saturn, while S/2004 S2 appears to circle the planet at roughly 211,000 kilometers (131,000 miles). More precise orbit sizes and shapes, as well as any tilt the orbits might have relative to Saturnís ringplane, will require the acquisition of future imaging observations by the Cassini cameras.
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.