Cassini discovers Saturns new moon

The NASA/ESA Cassini spacecraft has spotted a small, previously unknown moon circling Saturn. The tiny world - presently thought to be only about two kilometres wide - orbits Saturn at a distance of 197,700 kilometres.

Washington, July 20 : The NASA/ESA Cassini spacecraft has spotted a small, previously unknown moon circling Saturn. The tiny world - presently thought to be only about two kilometres wide - orbits Saturn at a distance of 197,700 kilometres.

According to a NASA statement, the moon given the provisional designation S/2007 S4, was first spotted in Cassini images taken on May 30, 2007 and subsequent searches through images taken by the spacecraft over the previous three years turned up additional detections of the moon, helping researchers refine their calculations of its orbital path.

The moon orbits Saturn between the paths of Methone and Pallene, two small moons, about four kilometres wide, also discovered in Cassini images in 2004. All three moons orbit between much larger Mimas and Enceladus.

"The fact that both Methone and S/2007 S 4 are dynamically locked with Mimas gives us a clue about their orbital history," said Carl Murray, a professor at Queen Mary, University of London, and the member of the Cassini Imaging Team leading the work on the new moon.

"There are numerous examples of these resonant mechanisms between moons in the Saturn system and they probably arise due to tides. In the case of these two small moons, the resonance ensures that they cannot hit Mimas, at least in the short term," he said.

Astronomers further say since the orbits of all three small moons lie close together, they might be remnants of a larger population.

"This trio of objects could be remnants of a collision or perhaps they are the lucky survivors of a larger population of material that failed to form a moon," said Prof. Murray.

"Either way there does seem to be a family connection. If we could get good data about their surfaces with Cassini, we could begin to unravel some of these mysteries," he said.

Cassini imaging scientists are now trying to look for future opportunities to zoom in on the new moon and refine its orbit, and to search for other companions.

"We've already identified times in the near future when we can take some pre-planned images and re-target them to get a closer look at this new body, and of course we're always on the lookout for additional moons. There are likely to be more of these very small bodies out there, and we hope to find them," said Carolyn Porco, imaging team leader and director of CICLOPS at the Space Science Institute.

ANI