Image of Pandora by Cassini.
Pandora is heavily cratered and, as revealed by the Cassini probe during its passage of the moon at a distance of 52,000 km on September 5, 2005, there are small grooves and ridges in the dust-fine icy material that has collected over the craters. The two largest craters identified measure about 30 km (19 mi) across.
Pandora and Prometheus, the inner shepherd of the F-ring, both follow chaotic orbits as a result of their gravitational interaction. Each time Pandora passes inside Prometheus, which happens about every 28 days, the two moons give each other a gravitational kick. Because neither moon's orbit is quite circular, the distance between them on those occasions – hence the strength of the kick - varies. The perturbations lead to changes in motion that are not periodic or predictable. This is the first observation ever of chaotic orbital motions in the Solar System. A larger moon of Saturn, Hyperion, had earlier been found to have chaotic rotation around its axis.
|discovery||1980, by S. Collins from Voyager 1 data|
|semimajor axis||141,720 km (88,080 mi)|
|diameter||103 × 80 × 64 km (64 × 50 × 40 mi)|
|mean density||0.5 g/cm3|
|escape velocity||0.019 km/s (68 km/h, 43 mph)|
|orbital period||0.629 days (15 h 6 min.)|