SETI: Moonlets Created and Destroyed in a Ring of Saturn

[bystander]

Moonlets Created and Destroyed in a Ring of Saturn
SETI Institute | 2014 Sep 08

Cassini spied just as many regular, faint clumps in Saturn's narrow F ring (the outermost, thin ring), like those pictured here, as Voyager did. But it saw hardly any of the long, bright clumps that were common in Voyager images. [url=http://photojournal.jpl.nasa.gov/catalog/PIA17154][b][i](Image credit: NASA/JPL-Caltech/SSI)[/i][/b][/url]

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There is an ongoing drama in the Saturnian ring system that causes small moons to be born and then destroyed on time scales that are but an eyeblink in the history of the solar system. SETI Institute scientists Robert French and Mark Showalter have examined photos made by NASA’s Cassini spacecraft and compared them to 30 year-old pictures made by the Voyager mission. They find that there is a marked difference in the appearance of one of the rings, even over this cosmologically short interval, a difference that can be explained by the brief strut and fret of small moons.

“The F ring is a narrow, lumpy feature made entirely of water ice that lies just outside the broad, luminous rings A, B, and C,” notes French. “It has bright spots. But it has fundamentally changed its appearance since the time of Voyager. Today, there are fewer of the very bright lumps.”

The bright spots come and go over the course of hours or days, a mystery that the two SETI Institute astronomers think they have solved.

“We believe the most luminous knots occur when tiny moons, no bigger than a large mountain, collide with the densest part of the ring,” says French. “These moons are small enough to coalesce and then break apart in short order.” ...

Analysis of clumps in Saturn’s F ring from Voyager and Cassini - Robert S. French et al

• Icarus 241 200 (Oct 2014) DOI: 10.1016/j.icarus.2014.06.035
  arXiv.org > astro-ph > arXiv:1408.2548 > 11 Aug 2014

Bright Clumps in Saturn Ring Now Mysteriously Scarce
NASA | JPL-Caltech | Cassini | 2014 Aug 08