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Linda SpilkerCassini Project ScientistEGU Press Conference29 April 2014

Cassini-Huygens Surprises: Today and Tomorrow

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Bright Feature Discovered at Edge of RingCassini discovered and tracked a bright, extended feature at the very outer edge of Saturn’s A Ring

Discovery image taken in April 2013

Murray et al 2014, Icarus

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A New Moon is Born???Bright ring feature appears to be associated with the birth of a small, icy infant moon

• The object, nicknamed “Peggy,” disturbs nearby ring particles at ring edge

• “Peggy” is ~2 km across and creates an entourage of particles that stick together in a bright arc about 1,200 km long and about 10 km wide

• Planets may form in a similar fashion from a ring-like disk orbiting a star

“The discovery and dynamical evolution of an object at the outer edge of Saturn’s A ring,” Murray, C.D., Cooper, N.J., Williams, G.A., Attree, N.O., Boyer, J.S., Icarus (2014), doi: http://dx.doi.org/10.1016/j.icarus.2014.03.024

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• Small objects form near A ring outer edge

• ~0.5 km radius from shadow projections

• Could be proto-Peggy clumps

• Outer region of A ring might be moonlet “nursery”

“Proto-Peggy” Clumps Cast Shadows near Equinox

FY14 FY15 FY16 FY17Cassini’s Final Four Years: Unique Science

• Explore new seasons at Saturn and Titan until northern summer solstice

• Titan: Look for waves on lakes and seas; measure depth of largest lake

• Enceladus: Sample plume emission for last time; best high resolution view of north pole

• Rings: Best lighting angle on lit rings (spring 2015 onward)

• Late, close orbits provide completely new, in-situ measurements

• Without Cassini, these types of observations could not be fulfilled for decades to come

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More Wonders Await

To view coming attractions video, visit http://saturn.jpl.nasa.gov

Back up Slides

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Peggy Headed Back into Ring

• In one year, Peggy’s location has moved inward ~5 km, back into Saturn’s A ring

• Migration caused by possible collisions with A ring clumps

• Plan to continue to monitor Peggy’s progress

• Unique opportunity to study planetary formation in a dusty disk

White arrows: Predicted location with no orbital migration Black arrows: Current location of Peggy feature

Recent image from C. Murray and N. Cooper