How Enceladus Interacts with Saturn's E Ring

Image comment: Cassini image of Enceladus and the E ring around Saturn
Image credits: NASA / JPL / Space Science Institute

When the NASA/ESA spacecraft Cassini first discovered that the Saturnine moon Enceladus was spewing out plumes of ice and water vapors from cracks at its south pole, they were amazed. This was a one-of-a-kind observation, and it changed the way astronomers looked at the gas giant's rings. Cassini revealed that some of the plumes reached far enough into space to merge with the planet's E ring, and add to it. New investigations with the space probe have recently yielded new insight into the interactions that develop between the moon and the ring, as well as on the cycle these particles take.

For the research, German investigators from the Max Planck Institutes for Nuclear Physics looked at data collected by a dust collector instrument aboard the spacecraft, and compared these readings with model data obtained through computer simulations. The team discovered that, although the ice plumes from the moon are added to the E ring, Enceladus reclaims most of its particles within the time frame of a few orbits, as it moves around its parent planet. The new investigation was only made possible by the fact that Cassini was recently driven nose-first through the E ring, during which time it collected samples in its detectors.

In addition to the samples, the probe was also capable of investigating the structure of the ring, as well as its vertical extent. Such studies are very difficult to conduct, because Saturn's rings, although extending from thousands of miles in width, are incredibly narrow, often not exceeding 3 meters. The recent dust analyzer measurements were taken as a reference point in new computer simulations, which provided astronomers with new data on how the E ring is supplied with material, the contribution that Enceladus makes to its growth, and the rates at which the two exchange matter. Details of the work appear in the latest issue of the respected scientific journal Icarus, PhysOrg reports.

The new work was conducted by MPI expert Sascha Kempf. The scientist explains that most icy particles fall back on Enceladus within two orbits, but adds that the ones which make it out of the moon's sphere of influence may endure for 50 to 400 years in the E ring, before eventually falling back to where they came from. During the nose-first “dives” in the ring, Cassini managed to identify a peculiar fact – matter appeared to be distributed randomly, rather than in the ordered fashion experts expected. More thorough study revealed that each spike was the impression left behind by one of Enceladus' ice and water plumes.