One More Shot

Summary: The Cassini spacecraft is on the last phase of its mission. It has begun a series of extremely elliptical orbits around Saturn before it will ultimately plunge into the planet and self-destruct. But while it is still working, there is data to collect. Already we have seen new images of the hexagonal clouds at the North pole of the planet and we are getting new images of the rings. But there is one object in particular that some astronomers have their sights set on.

First noticed in 2013 as a long, bright smudge along Saturn's A-ring, the mysterious object, known as Peggy, is one of the new image goals of the mission. There is no clear image of this smudge yet, and it would be a long time before another mission had a chance to photograph this mystery. The team only has until September to get the image, but thankfully Cassini will be flying close to this A-ring and the mysterious object has now been made into one of the last objectives for the mission.

Saturn can sometimes be used as a model for exoplanet formation in other star systems. The rings act similarly to how we believe dust gathers around a star until planets are formed. It is hoped that by studying Peggy more closely, we will gain more insight into the earliest stages of planet formation. Specifically it is hoped to be a model for how planets migrate. In the few years since Professor Carl Murray discovered this object, astronomers have been able to track it's motion and observe as it has drifted closer and further away from Saturn by a few kilometers.

Even more interesting, as scientists looked back through archival data with recent data from Cassini, they discovered that Peggy might have recently broken into two objects. Recent data shows another, smaller object following directly behind Peggy and orbital dynamics seem to indicate that they would have met in early 2015. Now there is the possibility that a collision of some sort caused both the fracturing of Peggy and also the new orbital radius.

Along with hoping to take better resolved images of Peggy, Cassini scientists also hope to determine the mass of Saturn's rings. Dr. Linda Spiker, the project scientist, points out that the mass can provide key clues about the age of the rings. This in turn would help with models of how the moons were formed. With lots of exciting science coming from the ringed planet this year, this is shaping up to be a great year for astronomy.

BBC News