As unmanned spacecraft Cassini gets closer to its final resting place, it’s getting closer than ever to the massive rings that orbit Saturn. NASA calls it the Grand Finale—a series of dives above Saturn’s poles and past narrow rings, collecting new data as it goes.
Cassini has been out there for 20 years, long past its original four-year mission timeline, and will commit suicide in September by dropping into Saturn’s atmosphere where it will be crushed under intense pressure. Before it goes, it’s sending back incredible photos as it makes riskier and riskier orbits. Let’s enjoy it while it lasts.
As you look at this photo, try to remember that every single pixel represents about a quarter-mile. This is just one short section of the outer B ring, which is perturbed by the nearby moon Mimas. Every time Mimas orbits Saturn, particles in this ring orbit twice, creating a periodic tugging motion that shifts the particles. The image has been cleaned up to remove blemishes so that you can appreciate the ring structure without underlying distractions. NASA/JPL-Caltech/Space Science InstituteAnother, closer view of Saturn’s B ring. This view, unlike the last, is relatively unprocessed, so you can still see the bright spots from cosmic rays and charged particle radiation as points against the otherwise smeared rings. During Cassini’s last trip over the rings, it took only short exposure picture to preserve the fine structure of the particles orbiting Saturn, but this time Cassini shot with long exposure times that emphasize the smearing. NASA/JPL-Caltech/Space Science InstituteMoonlets embedded in Saturn’s A ring, pictured here, cause the faint streaks that researchers termed “propellers.” You can’t see the moonlets themselves; you can only see the effects as they move through the rings. The bands seen at the left are density waves created by the interaction with the moon Prometheus. Tugs from Prometheus create a spiral-shaped pattern that winds around Saturn, kind of like a galaxy’s spiraling arms. NASA/JPL-Caltech/Space Science Institute
