NASA Quarterly
UVIS
Q1 - 2014
(November 2013 – January 2014)
Quarterly
1
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UVIS: Science Highlights
The Full Mimas
•
We know that Saturn’s moon Enceladus is the brightest
object in the solar system … at visible wavelengths, that is
•
Studies using Cassini’s UVIS instrument find that Mimas
is actually brighter than Enceladus at far-UV wavelengths
(light not seen by the human eye)
•
This particularly obvious at small phase angles … when
Mimas becomes a “full Moon”
•
It is believed that this is due to the photometric behavior
(opposition surge) of Mimas vs Enceladus… Enceladus’s
surface may be covered with such fine plume and E-ring
grains that there isn’t much of an opposition surge
•Mimas
•Enceladus
A.R. Hendrix
Quarterly
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UVIS: Science Highlights
Seasons on Saturn’s
moon Tethys
detected by Cassini’s UV spectrograph
A UV observation of Tethys (July 2007)
shows the brightest region in the northern
hemisphere.
The sub-solar point was south of the equator
at this time.
A later observation (April 2012), when the
sub-solar point had shifted northward,
indicates that the brightest region seems to
have shifted southward.
Solar photochemistry with the surface ice
produces hydrogen peroxide (H2O2) which is
dark in the UV, making the sub-solar region
relatively dark. We expect that later in the
mission, the northern region on Tethys will be
come even darker as the H2O2 accumulates.
A.R. Hendrix
Quarterly
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UVIS: Accomplishments
Science Highlights (from this quarter: Nov 2013 – Jan 2014)
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Colwell: Complete new model of self-gravity wakes incorporating UVIS and VIMS occultation data.
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Colwell: Self-gravity wake modeling making use of both VIMS and UVIS occultation data provides a new way
to study the population of the smallest particles in the A ring. We find that the size of the smallest particles
decreases in the outer third of the A ring, and the number of small particles increases in the outer third of the
A ring.
–
Esposito: A dynamical model of ring haloes around strong resonances in Saturn’s rings can explain their
general characteristics and dimensions. The analysis indicates that the resonance stirring triggers aggregate
formation and fragmentation at these perturbed locations. The freshly uncovered ring particle surfaces are
bombarded by micro-meteorites causing the spectral changes seen in haloes.
Quarterly
Colwell: Identify highest priority observations for the F Ring and Proximal orbits, including particletracking occultations and dedicated UV imaging of the rings at high resolution.
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UVIS: Accomplishments
• Publications
–
–
–
–
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Published this quarter
0
In press (Went into press Nov 2013 – Jan 2014, also includes still in press from earlier quarters) 7
Submitted (Submitted Nov 2013 – Jan 2014, also includes submitted earlier and still in review)
7
Published 2014 to date (since Nov. 2013)
0
Published entire mission
167
• Presentations at scientific conferences (Nov 2013 – Jan 2014)
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6 presentations at AGU, San Francisco, December 9-13 (Royer, Hendrix, Colwell (3), Esposito)
• Public Outreach and Press Activities (Nov 2013 – Jan 2014)
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–
–
Quarterly
2: public talks
1 : press releases
0: press conferences (phone interviews)
5
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UVIS: Plans
– Science Plans (Feb – Apr 2014)
•
Bradley: Continue investigation of ring particle albedo. Compare Saturn ring spectra with Saturn icy moon spectra. Compositional
modeling of ring particles using ring particle albedo and optical constants of candidate materials
•
Bradley: Compare Saturn ring spectra with Saturn icy moon spectra.
•
Bradley: Compositional modeling of ring particles using ring particle albedo and optical constants of candidate materials.
•
Colwell: Complete initial paper on stellar occultation statistics.
•
Colwell: Continue work on new self-gravity wake model.
•
Colwell: Work with Becker on diffraction modeling. Begin paper preparation.
•
Colwell: Paper on faint and narrow rings is in production (student Bryce Bolin is lead author).
•
Colwell: Paper on self-gravity wakes is in preparation (Colwell or Jerousek lead author).
•
Colwell: Submit new and updated occultation data sets to the Planetary Data System. [still pending per Josh]
•
Colwell: Paper on analysis of Rev 9 solar occ diffraction signal from F ring is in preparation (student Becker is lead author).
•
Yung: UVIS spectra will be analyzed using a scattering radiative transfer code, including the spherical geometry involved in the
Cassini observations. The gaseous absorptions used in the radiative model will be taken from previous papers by this group.
– Publications (Feb – Apr 2014) In preparation (includes submitted, but not yet published)
Quarterly
•
1 paper in press in an AGU monograph on the auroras
•
1 paper in review at ApJS
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1 papers in press in Discoveries of Modern Science
•
1 papers in review in GRL
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1 paper in press and 3 in review in Icarus
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1 paper in press and 1 in review in JGR
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1 paper in press in J. Mol. Spectrosc.
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1 paper in review and 1 in press in Planet. Space Sci.
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1 chapter in press in the book Titan: Surface, Atmosphere and Magnetosphere
6
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UVIS: Plans
Continued from last page
–Upcoming presentations at scientific conferences (Feb – Apr 2014)
•
2 presentations at EGU, Vienna, Austria, April 28- May 2 (Esposito, Colwell)
–Public Outreach and Press Activities (Feb – Apr 2014)
Quarterly
•
0: public talks
•
0: press releases
•
0: press conference (phone interview)
7
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Backup Material
Quarterly
8
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UVIS: Publications - 2014
•
None yet
Quarterly
9
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UVIS: Publications (In Press)
•
Esposito, L.W.E. 2013. Saturn’s Rings. Discoveries in Modern Science. (Went to press August 28, 2013)
•
Gurnett, D. and W. Pryor. 2012. Auroral Processes Associated with Saturn's Moon Enceladus. For inclusion in an
AGU monograph on the auroras. (Accepted spring 2012)
•
Gustin, J. , J.C. Gerard, D. Grodent, G.R. Gladstone, J.T. Clarke, W.R. Pryor, V. Dols, B. Bonfond, A. Radioti, L.
Lamy, J.M. Ajello. 2012. Effects of methane on giant planet's UV emissions and implications for the auroral
characteristics. J. Mol. Spectrosc. (Accepted. March 29, 2013.)
•
Kammer, J.A., D.E. Shemansky, X. Zhang, Y.L. Yung. 2013. Composition of Titan's Upper Atmosphere from
Cassini UVIS EUV Stellar Occultations. Planet. Space Sci. (Accepted 6/12/13.)
•
Lamy, L., Prange, R. Pryor, W., Gustin, J. Badman, S., Melin, H. Stallard, T., Mitchell, D.G., Brandt, P.C. 2013.
Multi-spectral simulations diagnosis of Saturn’s aurorae throughout a planetary rotation. JGR-Space Physics.
(Accepted June 17, 2013)
•
Nicholson, P. D., R. G. French, M. M. Hedman, E. A. Marouf, and J. E. Colwell. 2013. Noncircular Features in
Saturn’s Rings I: The Edge of the B Ring. Icarus. (In press as of Sept 9, 2013)
•
West, R., P. Lavvas, C. Anderson, and H. Imanaka. 2012. Titan Haze. A chapter in Titan: Surface, Atmosphere
and Magnetosphere. Eds. I. Mueller-Wodarg, C. Griffith, T. Cravens and E. Lellouch. Cambridge University Press
[Cambridge Planetary Science Series]. (Accepted March 1, 2012)
Quarterly
10
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UVIS: Publications (Submitted)
•
Carbary, J., D. Mitchell, and W. Pryor. 2012. Correlation of Saturn's Ultraviolet Aurora with Energetic Neutral
Atoms. GRL. (Submitted June 28, 2012)
•
Cuzzi, J. N., A. D. Whizin, R. C. Hogan, A. R. Dobrovolskis, L. Dones, M. R. Showalter, J. E. Colwell, and J. D.
Scargle 2013. Saturn’s F Ring Core: Calm in the Midst of Chaos. Icaru.s (Submitted September 2013)
•
Gustin, J., Moses, J., Gerard, J-C., and Grodent, D. Saturn H2 density and temperature profiles at low, medium
and high latitudes from Cassini UVIS solar occultations. Icarus. (Submitted on Dec. 3 per Gustin)
•
Hendrix, A.R. Shemansky, D.E. et al. 2013. Io: FUV and EUV Spectroscopy from Cassini. Icarus. (Plan to submit
in October)
•
Heays, A.N., Ajello, J.M., Aguilar, A., Lewis, B.R., Gibson, S.T. 2014. The high resolution EUV spectrum of N2 by
electron impact. ApJS (Submitted Nov 29, 2013 per Ajello)
•
Li, C., X. Zhang, M.-C. Liang, Y.L. Yung. 2013. Eddy Diffusion Profile of Titan's Atmosphere Revealed by Cassini
Observations. Planet. Space Sci. (Submitted Nov. 2012.)
•
Mitchell, D.G., P. C. Brandt, J.F. Carbary, W.S. Kurth, S.M. Krimigis, C. Paranicas, N. Krupp, D.C. Hamilton, B.H.
Mauk, G. B. Hospadarsky, M.K. Dougherty, W. R. Pryor. 2013. Injection, Interchange And Reconnection: Energetic
Particle Observations In Saturn's Magnetotail. JGR. (Submitted August 15, 2013, but didn’t know last quarter)
Quarterly
11
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UVIS: Science Presentations – Q1-2014 (Nov 2013-Jan 2014)
– AGU, San Francisco, December 9-13
Quarterly
•
E. M. Royer; A. R. Hendrix: Unexpected Far-Ultraviolet Photometric Characteristics On Mimas
•
Hendrix et al: UV-IR Spectra of the icy Saturnian satellites
•
Colwell, J. E., J. H. Cooney, L. W. Esposito, M. Sremcevice. Particle Sizes and Clumps from Occultation
Statistics
•
Becker, T. M., J. E. Colwell, L. W. Esposito."Measuring Particle Sizes in Saturn's F Ring from Diffracted
Sunlight in Cassini UVIS Solar Occultation
•
Spilker, L. J., E. Deau, G. Filacchione, R. Morishima, M. M. Hedman, P. D. Nicholson, J. E. Colwell.
Multiwavelength Studies of Saturn's Rings
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Esposito: Predator-Prey Model for A-Ring Haloes
12
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UVIS: Outreach – Q1-2014 (Nov 2013-Jan 2014)
•
•
EPO: Talks to school children, teachers and public
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Colwell: University of Florida Astronomy Department, November 20. Ghosts, Pebbles and Propellers: Accretion
in Saturn's Rings and the Protoplanetary Disk. 50 people in attendance.
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Esposito: Mysteries of Saturn’s Rings, January 16, Boulder Chautauqua.
Press releases
–
•
Pryor: Cassini Project press release in January on Hubble-Cassini joint auroral observations including a UVIS
movie.
Press conferences & interviews
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None this quarter
Quarterly
13
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