I: Introduction (3 pgs) II: Particle size distribution (5 pgs)

1. Ring Particle Composition and Size DistributionJ. Cuzzi, R. Clark, L. Dones, G. Filacchione, R. French, R. Johnson, E. Marouf , L. Spilker I: Introduction (3 pgs) II: Particle size distribution (5 pgs) III: Particle composition (as observed today) (10 pgs) IV: Possible evolutionary processes (tie to Charnoz et al chapter) (2 pgs) V: Comparison with other icy objects (2 pgs) VI: Discussion, summary, etc. (1 pg) VII: References (2 pgs) Figures: looks like 15-20 now. Goal is to have at least one column width figure per page, and several larger color figures

2. I: Introduction (3 pgs) (Cuzzi) A: Composition perhaps the best clue to ring origin (given extensive dynamical evolution) comparison with other icy bodies there are important evolutionary effects B: Overview of chapter

3. II: Particle Size Distribution (5 pgs) • (French, Marouf; Cuzzi) • A: review of pre-Cassini understanding in general • B: describe observations (RSS occ, stellar occ (Q), microwave) • C: what is a ring particle: transient? building blocks? • how distinguish ring particles from ultrafine structure? • D: "particles" vs regoliths and grains (tie to next section) • E: theory (DEBS, Longaretti, propeller objects, etc); • large "particles" - tie to structure/dynamics chapter • F: Cassini observations by region, not by instrument • A ring, B ring, Cassini Div and C ring, F ring • G: correlations and implications

4. Particle sizes in the rings 3 wavelength Radio occultation Blue= smaller particles; red= larger, white= high opacity

5. “Variance” properties of the stellar occultation signal

6. “Ring particles” or “structures”?

7. The Opposition Effect: Intense backscatter from shadow hiding or from particle surfaces ??? The Opposition Effect: Coherent backscatter from particle surfaces; No support for a many-particle thick layer I/F Low albedo w 1.5 w High albedo Phase angle Nelson et al 2006; Hapke et al 2006 LPSC Wavelength (microns)

8. The Opposition Effect: Intense backscatter from shadow hiding or from particle surfaces ??? Regolith grain size can also be constrained From depths of water ice bands I/F Low albedo w 1.5 w High albedo Phase angle Nelson et al 2006; Hapke et al 2006 LPSC Wavelength (microns)

9. III: Particle composition (as observed today) (10 pgs) (Clark, Dones, Filacchione, Spilker; Cuzzi) A: review of pre-Cassini understanding in general B: describe observations: spectral (VIMS V and IR), color, thermal, microwave, CDA C: discussion of modeling tools ring I/F vs particle albedo difference Hapke and other regolith theories; lab spectra (Appendix??) D: Cassini observations by region, not by instrument A ring, B ring, Cassini Div and C ring, F ring E: correlations and implications

10. Thermal IR and microwave: change from emitting to scattering behavior Low microwave emission is the primary argument supporting nearly pure (>90%) water ice composition Van der Tak et al 1999  3.6cm Data tabulated in Esposito et al 984

11. Thermal infrared Transition between thermal IR and microwave is poorly understood. Will constrain embedded impurities and regolith grain size. Cassini 2cm radiometry is ongoing Thermal inertia - regolith properties ? Microwave

12. The rings look red Color enhanced

13. There are color variations on all scales Voyager data

14. Cassini ISS

15. Saturn’s entire B ring Pre-Cassini: one spectrum for Saturn’s entire B ring HST HST IRTF IRTF model model R R wavelength (microns) wavelength (microns) Now have VIMS spectra every few hundred km Dominated by water ice; Red spectrum at visual wavelengths Working with UCSC grad student

16. C B A 0.3 - 0.5 slope ice band depths 0.6 - 0.9 slope Nicholson et al 2006; Icarus, in press

17. Typical VIMS spectra (Nicholson et al; Clark) 2.7x 2.42 “Phoebe band” No weak H2O bands

19. Size distribution AND composition information; which chapter?

20. IV: Possible evolutionary processes (2 pgs) (Cuzzi, Johnson) (tie to Charnoz et al chapter) A) Meteoroid bombardment B) Oxygen ring atmosphere

21. . m Meteoroid Bombardment and Ballistic Transport Main rings intercept roughly their own mass in the age of the solar system; Rings get “polluted”; material gets moved around by ejecta Cassini is attempting to measure the mass of the rings Also review Pioneeer 11 mass measurements? Vej Y ice Increasing radius non-ice

22. Plasma wave tones from ??-sized meteoroids hitting Saturn’s rings (SOI) D. Gurnett & Cassini RPWS team Chambers et al this mtg

23. V: Comparison with other icy objects (2 pgs) (Clark, Filacchione, Dones, Spilker, Cuzzi) Regular satellites of Saturn 1.3x 1.5x 1.5x

24. Interlopers from the outer solar system? Barucci et al 2.9x Triton visual Buratti et al Nature 1999 Triton (UV) Stern 1994

25. VI: Discussion, summary, etc. (1 pg) Logistics and plans: Working backwards from the meeting, I will need at least a week to put together a powerpoint talk from the draft chapter. I have a pre-London Rings workshop July 24-26. Thus all sections must be submitted, to page limits indicated, by mid July. Dick French has offered to set up a WIKI site as a central location for image and data products, drafts, etc. Planning on two months after receipt of all data products to discuss, compare, and interpret data, get everything into a common format, and write a draft of each section means all data are required by mid-May. Note that results will be organized and presented by ring and not by team. Have asked Bob Johnson to submit his piece on ring atmosphere a month earlier as it will lead to some “new” thinking and rewriting. The final massaging of the sections and image/data products will be done in the few weeks right after the meeting.