Scientists are still trawling through the trove of data received from the final days of NASA's legendary Saturn probe, Cassini.
New research using data from the spacecraft's closest-ever flybys of the gas giant revealed new details about the gas giant's tiny ring moons. In a recently published paper, researchers revealed that the mysterious satellites are covered with the same materials from the planet's famous rings and icy particles ejected by Enceladus.
The findings give scientists new insight into how the unusual moons were formed and how they interact with the rings of Saturn.
Saturn's Mysterious Mini-Moons
Saturn has a total of 62 moons, but the study published in Science on Thursday, March 29, focuses on five small moons nestled close to the planet's ring system: Pan, Daphnis, Atlas, Pandora, and Epimetheus. During Cassini's six ring-grazing flybys between December 2017 and April 2017, the spacecraft snapped images and made scientific observations of the mysterious mini-moons.
According to scientists, the ring moons are porous, suggesting that they were formed in multiple stages. Scientists suspect that the moons have a denser core that was a remnant of a much larger object that broke apart. Material from Saturn's rings settled into the core, building up and congealing in time, creating the mini-moons that orbit that gas giant today.
This explains the rather odd shapes of the ring moons.
"We found these moons are scooping up particles of ice and dust from the rings to form the little skirts around their equators," stated Bonnie Buratti of NASA's Jet Propulsion Lab who is one of the co-authors of the study. "A denser body would be more ball-shaped because gravity would pull the material in."
The moons closest to Saturn, Daphnis and Pan, have the most ring materials. The other three — Atlas, Prometheus, Pandora — are much farther from the planet and have a mix of ring material and particles from the plumes ejected by Enceladus.
Scientists also noted that the closest moons to Saturn have a reddish hue while the farthest appear blue.
The new findings could also be applied to small moons of the other outer planets and even asteroids.
Cassini Completes Its Mission
NASA's Cassini made its final approach of Saturn on Sept. 15, 2017. The spacecraft dove into the planet, making observations and beaming back data to Earth while it burned up in the atmosphere.
The spacecraft was launched on Oct. 15, 1997, to explore Saturn, including its rings and its many moons.