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Space Topics: Saturn

Pandora (S/1980 S26)

Outer Shepherd of the F ring

Pandora in color
The best Cassini view of Pandora from the September 5, 2005 flyby. The view is in enhanced color, comprised of three images captured through infrared, green, and ultraviolet filters. Credit: NASA / JPL / Space Science Institute / Justin Phillips

Size: Irregular, 114 x 84 x 62  kilometers - 13th largest moon of Saturn
Orbital radius: 141,700 kilometers - 2.35 Saturn radii - outer shepherd of the F ring
Orbital period: 0.6285 days - about 1/25 of Titan’s
Discovery: 1980 by S. Collins et al.

Pandora is a tiny moon that orbits just outside Saturn's F ring.  Along with Prometheus, the F ring's inner shepherd, Pandora is probably responsible for maintaining the edges of the F ring and keeping the gaps on either side of the F ring clear.

Prometheus and Pandora herd the F ring (movie)
Credit: NASA / JPL / Space Science Institute

This movie sequence from Cassini shows dark drapes in the inner strands of Saturn's F ring caused by the gravitational influence of the shepherd moon Prometheus. Prometheus appears first in the sequence, interior to the F ring, and Pandora follows along outside of the ring. Prometheus orbits closer to Saturn, and thus faster, than the icy particles that make up the F ring. The moon passes closest to the ring at "apoapse", when it is farthest from Saturn. It is during these apoapse passages that Prometheus has its greatest influence on the fine ring material. With time, the ring material previously affected falls behind so that on the next apoapse passage of Prometheus, a new gore in the inner ring material is made. The material closer to Prometheus orbits the planet faster than the material closer to the bright F ring core. The gores, together with the sheared-out material, create the dark, diagonal drapes. Visit the Planetary Photojournal to download a high-resolution, 170-frame version of this movie.

Flybys of Pandora

PandoraCassini
September 5, 2005 at 11:52 UTC
“14PA” nontargeted flyby
Closest approach altitude 51,888 kilometers