Prometheus

Discovered by S. Collins and others in 1980 from Voyager photos.

Prometheus is in Saturn's F-ring. 

Prometheus has a number of ridges and valleys and several craters about 20 km in diameter but appears to be less cratered than the neighboring moons Pandora, Janus and Epimetheus.

   From their very low densities and relatively high albedos, it seems likely that Prometheus is a very porous icy body. 

   The 1995/6 Saturn Ring Plane Crossing observations found that Prometheus was lagging by 20 degrees from where it should have been based on Voyager 1981 data. This is much more than can be explained by observational error. It is possible that Prometheus's orbit was changed by a recent encounter with the F ring, or it may have a small companion moon sharing its orbit. 


 

Pandora

Discovered by Collins and others in 1980 from Voyager photos.

Pandora is also in Saturn's F-ring.
Pandora has at least two large craters 30 km in diameter. But it shows no linear ridges or valleys.