Baines, Kevin H.

Brown, R.H.

Buratti, B. J.

Clark, R.N.

Cruikshank, D.P.

Dalle Ore, C.

Filacchione, G.

Jaumann, R.

Nicholson, P.D.

Stephan, K.

English

Institute of Transport Research:Publications

2010 AGU Fall Meeting�You may print by clicking on this Print  button. To return to the previous page, close this browserwindow or click the 'X' button in the top right corner of the page.�ID# P13E-03Location: 306 (Moscone South)Time of Presentation: Dec 13 3:10 PM - 3:25 PM�Saturn's Icy satellites: The Role of Sub-Micron Ice Particles and Nano-sized Contaminants(Invited)R. N. Clark1; D. P. Cruikshank2; C. M. Dalle Ore2; R. Jaumann3; R. H. Brown4; K. Stephan3; B. J.Buratti5; G. Filacchione6; K. H. Baines5; P. Nicholson71. U.S. Geological Survey, Denver, CO, United States.2. NASA Ames, Moffett Field, CA, United States.3. DLR, Berlin, Germany.4. U. Arizona, Tucson, AZ, United States.5. JPL, Pasadena, CA, United States.6. INAF-IASF, Rome, Italy.7. Cornell, Ithaca, NY, United States.�The Visual and Infrared Mapping Spectrometer (VIMS) has obtained spatially resolved imagingspectroscopy data on numerous satellites of Saturn. The spectral trends on individual satellites and ascompositional gradients within the Saturn system show systematic trends that indicate variable icegrain sizes and contaminants. Compositionalmapping shows that the satellite surfaces are composed largely of H2O ice, with small amounts ofCO2, trace organics, bound water or OH-bearing minerals, and possible signatures of ammonia, H2Oor OH-bearing minerals, and dark, fine-grained materials. The E-ring coats the inner satellites withsub-micron ice particles. The Cassini Rev 49 Iapetus fly-by on September 10, 2007, provided imagingspectroscopy data on both the dark material and the transition zone between the dark material and thevisually bright ice on the trailing side. The dark material has very low albedo with a linear increase inreflectance withwavelength, a 3-micron water absorption, and a CO2 absorption. The only reflectance models that canexplain the trends include highly absorbing sub-micron materials that create Rayleigh absorption.Radiative transfer models that include diffraction from Rayleigh scattering andRayleigh absorption are necessary to match observed data. The dark material is well matched by a highcomponent of fine-grained metallic iron plus a small component of nano-phase hematite. Spatiallyresolved Iapetus data show mixing of dark material with ice and the mixtures display a blue scatteringpeak and a UV absorption. The blue scattering peak and UV-Visible absorption is observed in spectra ofall satellites at some locations where darkmaterial is mixed with the ice. Rayleigh scatteringand Rayleigh absorption have also been observed in spectral properties of the Earth's moon. Rayleighabsorption requires high absorption coefficient nano-sized particles, which is also consistent withmetallic iron. TheUV absorber appears to have increased strength on satellite surfaces close to Saturn, with acorresponding decrease in metallic iron signature. Possible explanations are that the iron is oxidizedcloser to Saturn by oxygen in the extended atmosphere of Saturn's rings, or coverage by sub-micronE-ring ice particles, or a combination of both.Contact InformationRoger N. Clark, Denver, Colorado, USA, 80225, click here to send an emailAbstract�Central�-�Itinerary�abstract�details�popup http://agu-fm10.abstractcentral.com/planner?NEXT_PAGE=IT...1�of�2 12/21/10�15:05ScholarOne Abstracts® (patent #7,257,767 and #7,263,655). © ScholarOne, Inc., 2010. All Rights Reserved.ScholarOne Abstracts and ScholarOne are registered trademarks of ScholarOne, Inc.Terms and Conditions of UseAbstract�Central�-�Itinerary�abstract�details�popup http://agu-fm10.abstractcentral.com/planner?NEXT_PAGE=IT...2�of�2 12/21/10�15:05

Saturn's Icy satellites: The Role of Sub-Micron Ice Particles and Nano-sized Contaminants

Saturn's Icy satellites: The Role of Sub-Micron Ice Particles and Nano-sized Contaminants

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