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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