Cassini Saturn Planet and Atmosphere Science

PIA14905 shows a series of images taken from Dec 5, 2010 to April 22, 2011 of the largest storm observed since 1990. .

On this page:


Disclaimer: This webpage is to assist you on getting started with relevant literature and science data for the topic of your interest. The products located on this website are subject to change or become outdated over time. Thus, it is meant only to be a starting point for you to begin your journey to Saturn.

Overview

The Saturn Atmosphere and Interior Sections in Cassini Mission Final Report (PDF) summarizes the status of Saturn science, in 2018, as a result of Cassini exploration of the Saturn system. It also includes open questions that will be explored by future scientists.

Mission Science Highlights and Science Objectives Assessment provides a brief overview of the mission

Charm Talks is a series of talks given by the team that provides insight into discovery and development of understanding.

Mission Objectives:

  • Determine temperature field, cloud properties and composition of the atmosphere.
  • Measure global wind field, including wave and eddy components; observe synoptic cloud features and processes.
  • Infer internal structure and rotation of the deep atmosphere.
  • Study diurnal variations and magnetic control of ionosphere.
  • Provide observational constraints (gas composition, isotope ratios, heat flux) on scenarios for the formation and evolution of Saturn.
  • Investigate sources and morphology of Saturn lightning (Saturn electrostatic discharges, lightning whistlers).

Saturn Science Integration

How Cassini Saturn Science was Planned and Implemented (In preparation)

Saturn Atmospheric Modeling Working Group

At the end of Cassini’s prime mission, an end of mission composed of close flybys of Saturn was approved. This prompted the need to better understand Saturn’s upper atmosphere using data that was gathered by Cassini. The Saturn Atmospheric Modeling Working Group was formed to provide necessary information to Cassini’s Mission Planning and Spacecraft teams. The final report can be found here: Saturn Atmospheric Modeling Working Group Final Report (pdf).
Atmospheric structure inferred from Cassini's final orbits

Saturn’s atmospheric structure inferred from Cassini’s Attitude Control Flight Data: Andrade, L.G., 2018. Skimming through Saturn's Atmosphere: The Climax of the Cassini Grand Finale Mission. 2018 AIAA Guidance, Navigation, and Control Conference, 8–12 January 2018, Kissimmee, Florida. https://doi.org/10.2514/6.2018-2111.

Saturn’s atmospheric structure inferred from Cassini’s Doppler radio data:Boone, D.R., M. Wong, J. Bellerose, and D. Roth, 2018. Preliminary Saturn Atmospheric Density Results From Cassini's Final Plunge. AAS 18-115 in "Advances In The Astronautical Sciences, Guidance, Navigation and Control 2018”. Feb. 1-7, 2018, Breckenridge, CO.. Pub. 2018, 1362pgs. Ed. Cheryl A. H. Walker.


Saturn Data Resources

Included below are data resources that span the entire mission. These may help understand all of the sub-topics below.

Search Tools

  • The Event Calendar is one way to find data associated with particular events such as auroral observations.
  • OPUS is a tool used to search for CIRS, ISS, UVIS and VIMS data all in one place. This URL is pre-filled with an example search for Saturn images.

Reference Tables

  • The Full Saturn Observation Guide [CSV] [TXT] is a document filled with information about every Saturn observation made by Cassini, including primary and secondary instruments, start and end time, segment type, and science areas.
  • The Observation Key [CSV] [TXT] describes the nomenclature used in the observation guide.
  • Digit is a geometry and trajectory visualization tool for pointing reconstruction across the mission, using SPICE information to represent targets accurately.
  • The Tour Atlas Readme File is a collection of tables of geometric positions, velocities, timing, altitude, and spacecraft attitudes that were useful in planning Cassini's response. It also includes times for all opportunities for Saturn solar, radio, and stellar occultations. Implemented occultations are found in the Event Calendar and Saturn segment documentation.

Segment times and mapping to science category are available to download as [XLSX] or [CSV]

Saturn Segment Table

This table outlines each Saturn observation segment by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations. Table of Time Periods with Saturn-Focused Observations
    Segment Times, Movies, Legacy Packages and Visualizations

Saturn Formation and Evolution

This section is associated with the objective to provide observational constraints on the formation and the evolution of Saturn. Cassini obtained measurements relevant to (1) the abundances of helium and volatiles such as ammonia and phosphine, (2) the D/H ratio from CH3D/CH4 measurements, and (3) the structure of the interior and core from gravity and magnetic field place constraints on how Saturn formed and evolved. Key instruments involved are CIRS, VIMS, MAG, and RSS. Science Objectives included:
  • Provide observational constraints (gas composition, isotope ratios, heat flux, ...) on scenarios for the formation and the evolution of Saturn.

Key Review Publications

In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • Origin of the Saturn System. pp. 55-74. Johnson, T. V. and Estrada, P. R.
    In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press (2018)
  • The Origin and Evolution of Saturn, with Exoplanet Perspective. Atreya, S. K., Crida, A., Guillot, T., Lunine, J. I., Madhusudhan, N., and Mousis, O.

Reference Data


Saturn Segment Table

The table below outlines the Saturn observation segments related to Saturn Formation by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations.
Also available to download as [XLSX] or [CSV] Table of Time Periods with Formation and Evolution Observations
    Segment Times, Movies, Legacy Packages and Visualizations

Interior Fundamentals

Sub-Topics:

Gravity and Other Fundamental Parameters
Shape of Saturn
Rotation Rate
This section pertains to the current knowledge, circa Summer 2018, of properties associated with Saturn's interior structure and rotation rate of the deep atmosphere. These include the values of gravitational moments through J10 and higher, the present shape of Saturn as expressed by Legendre polynomial coefficients for the 1-bar level, the magnetic field structure, and current estimates of the rotational period as derived from analysis of kronoseismological signals observed in the rings and other techniques. Science Objectives include:
  • Infer the internal structure and rotation of the deep atmosphere.
  • Determine Saturn's rotation rate and internal structure despite the planet's unexpected high degree of axis symmetry.
Key instruments involved are CIRS, MAG, RSS, RPWS, UVIS, and VIMS.

OVERVIEW

Key Review Publications

    In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • The interior of Saturn. pp. 75 - 81. Hubbard, W. B., Dougherty, M. K., Gautier, D., and Jacobson, R.
    In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press. (2018)
  • The interior of Saturn. Fortney, J. J., Helled, R., Nettelmann, N., Stevenson, D. J., Marley, M. S., Hubbard, W. B., and Iess, L.

Reference Data


Saturn Segment Table

The table below outlines the Saturn observation segments related to Saturn Interior by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations.
Also available to download as [XLSX] or [CSV] Table of Time Periods with Interior Observations
    Segment Times, Movies, Legacy Packages and Visualizations

Gravity and Other Fundamental Parameters

Data and higher order products related to Saturn's gravitational field, and internal structure can be found here. The key instrument contributing to this subject is RSS.
The following papers and tables contain data useful for modeling of Saturn's gravity.
Iess, L., et al. Measurement and implications of Saturn’s gravity field and ring mass. Science, 10.1126/Science.aat2965 (2019). [DOI: 10.1126/science.aat2965] Tables
    might be a paper
    mass
    gravity moments
    rotation rate
    equatorial radius
    polar radius
Table 1 Measured gravity harmonic coefficients of Saturn (un-normalized; reference radius 60330 km) and total ring mass (in units of Mimas’ mass) [PDF].

The J2 value includes a constant tidal term owing to the average tidal perturbation from the satellites. The associated uncertainties are recommended values to be used for analysis and interpretation. For the zonal harmonics they correspond to 3 times the formal uncertainties. The solution for the total ring mass (A+B+C) is stable independently of the adopted dynamical model (table S2) and the uncertainty reported is the 1σ formal uncertainty. See table S2 for our total ring mass estimates for several models of the unknown accelerations

ValueUncertainty
J2 (x106)16290.5730.028
J3 (x106)0.0590.023
J4(x106)-935.3140.037
J5 (x106)-0.2240.054
J6(x106)86.340.087
J7(x106)0.1080.122
J8(x106)-14.6240.205
J9 (x106)0.3690.26
J10 (x106)4.6720.42
J11(x106)-0.3170.458
J12(x106)-0.9970.672
Ring mass (MM)0.410.13


Table 2 Comparison of observed and calculated gravitational harmonics (un-normalized; reference radius 60330 km) [PDF].

Where two values are given they denote the minimum and maximum values from the suite of models. The physical models in column 3 match the observed J2 and J4 in Table 1, over a parameter space considering ranges of Smet, Ymol, Zmol, rc and rotation periods from 10h32m44s to 10h47m06s. For the same span of rotation periods, column 4 reports a wider range from models that match only J2 and allow for density modifications assuming rc = 0.2. For J6-J10, the discrepancy between measurements and uniform rotation models is large for all models that assume uniform rotation. Column 5 shows a representative model with DR on cylinders and a deep rotation period of 10h39m22s that matches measurements from J2 to J10.


MeasurementsPhysical models with
uniform rotation		Uniform rotation model with
modified density profiles		Physical model with
differential rotation
J216290.573 ± 0.02816290.5716290.5716290.573
J4-935.314 ± 0.037-935.31-990.12-902.93-935.312
J686.340 ± 0.08780.7481.7675.6990.4286.343
J8-14.624 ± 0.205-8.96-8.7-10.26-7.97-14.616
J104.672 ± 0.4201.081.130.971.334.677


Table 3 Contribution to the higher gravity harmonics ΔJ8 and ΔJ10 resulting from differential rotation and thermal-wind optimization. [PDF]

The deviation (Column 1) is the difference between the measured J8 and J10 (Table 1) and the average of the computed values from the 11 CMS models with uniform rotation (Table 2). Two optimizations are shown: one without latitudinal truncation of the zonal flow, resulting in the reconstructed zonal wind profile shown in Fig. 4A and with a flow depth of 9363 km (Column 2), and the second with the flows truncated at latitude 60° (Fig. 4B) and a flow depth of 8832 km (Column 3). Columns 4 and 5 show the deviations calculated with the thermal-gravity equation (48) for similar wind profiles. The solutions from thermal wind are closer to the measurement because the optimization was done using the thermal wind method, but the thermal-gravity solutions also match the observations within 10%.


DeviationThermal-wind
solution		Thermal-wind solution
truncated at latitude 60°		Thermal-gravity
solution		Thermal-gravity solution
truncated at latitude 60°
ΔJ8-5.600 ± 0.205-5.624-5.533-5.758-5.759
ΔJ103.528 ± 0.6593.5703.663.9744.037


R. A. Jacobson et al., The Gravity Field Of The Saturnian System From Satellite Observations And Spacecraft Tracking Data. Astronomical J., 132, 2520-2526. (2006) [DOI: 10.1086/508812]

Table 3: Saturnian System Gravity Field from Jacobson et al. [PDF]

Parameter Null et al. (1981) Campbell & Anderson (1989) Jacobson (2004) This Paper
GMSun/GMsys... 3498.09 ± 0.22 3497.898 ± 0.018 3497.893 ± 0.005 3497.9018 ± 0.0001
GM (km3 s-2)...
     System... 37938544.0 ± 2400.0 37940630.0 ± 200.0 37940672.0 ± 59.0 37940585.2 ± 1.1
     Saturn... 37929085.0 ± 2400.0 37931272.0 ± 200.0 37931284.0 ± 57.0 37931207.7 ± 1.1
     Mimas... 2.50± 0.06a 2.50 ± 0.06a 2.55 ± 0.05 2.5023 ± 0.0020
     Enceladus... 4.9± 2.4b 4.9 ± 2.4b 6.9 ± 1.5 7.2096 ± 0.0067
     Tethys... 41.5 ± 0.8a 45.0 ± 10.0 41.21 ± 0.08 41.2097 ± 0.0063
     Dione... 70.2 ± 2.2b 70.2 ± 2.2b 73.12 ± 0.02 73.1127 ± 0.0025
     Rhea... 151.0 ± 34.0 154.0 ± 4.0 155.0 ± 5.0 153.9416 ± 0.0049
     Titan... 9059.0 ± 114.0 8978.2 ± 1.0 8978.1 ± 0.8 8978.1356 ± 0.0039
     Hyperion... 1.1 0 0.72 ± 0.35 0.3727 ± 0.0045
     Iapetus... 129.0 ± 49.0 106.0 ± 10.0 130.0 ± 17.0 120.5117 ± 0.0173
     Phoebe... ... ... 0.5 ± 0.2 0.5534 ± 0.0006
J2(×106)... 16299.0 ± 18.0 16298.0 ± 10.0 16292.0 ± 7.0 16290.71 ± 0.27
J4(×106)... -916.0 ± 38.0 -915.0 ± 40.0 -931.0 ± 31.0 -935.83 ± 2.77
J6(×106)... 81 103.0 ± 50.0 91.0 ± 31.0 86.14 ± 9.64
J8(×106)... ... -10.0c -10.0c -10.0c
αp (deg)... 40.6076 ± 0.0230a 40.580 ± 0.016d 40.5955 ± 0.0036e 40.58279 ± 0.00201f
δp (deg)... 83.5219 ± 0.0036a 83.540 ± 0.002d 83.5381 ± 0.0002e 83.53763 ± 0.00021f
αp (deg century-1)... ... ... -0.04229g -0.04229g
δp (deg century-1)... ... ... -0.00444g -0.00444g
NOTE.—Reference radius for the gravitational harmonics: 60,330 km.
a Adopted from Kozai (1957).
b Adopted from Kozai (1976).
c Theoretical estimate used by Nicholson & Porco (1988).
d Adopted from Simpson et al. (1983).
e At epoch 1980 November 12, 23:46:32, from French et al. (1993).
f At epoch 2000 January 1, 12:00:00.
g Derived from the precession rate of Nicholson et al. (1999).

Table 4: Physical Properties from Jacobson et al. [PDF]

Body Radius (km) Mass (1022g) Density (g/cm3)
Saturn... 58232.0 ± 6.0a 56832592.0 ± 8515.0 0.6873 ± 0.0002
Mimas... 198.30 ± 0.30b 3.7493 ± 0.0031 1.1479 ± 0.0053
Enceladus... 252.10 ± 0.10b 10.8022 ± 0.0101 1.6096 ± 0.0024
Tethys... 533.00 ± 0.70b 61.7449 ± 0.0132 0.9735 ± 0.0038
Dione... 561.70 ± 0.45b 109.5452 ± 0.0168 1.4757 ± 0.0036
Rhea... 764.30 ± 1.10b 230.6518 ± 0.0353 1.2333 ± 0.0053
Titan... 2575.50 ± 2.00c 13452.0029 ± 2.0155 1.8798 ± 0.0044
Hyperion... 133.00 ± 8.00d 0.5584 ± 0.0068 0.5667 ± 0.1025
Iapetus... 735.60 ± 1.50b 180.5635 ± 0.0375 1.0830 ± 0.0066
Phoebe... 106.60 ± 1.00e 0.8292 ± 0.0010 1.6342 ± 0.0460
a Lindal et al. (1985).
b Thomas et al. (2006).
c Lindal et al. (1983).
d Thomas et al. (1995).
e Porco et al. (2005b).

Shape of Saturn

Data and higher order products related to the shape of Saturn's "surface" can be found here. Key instruments contributing to this topic are: RSS and UVIS.
The seminal paper defining the Shape of Saturn is Lindal, et al. (1985). In this paper, the equatorial and polar radius at 100 mbar are given as 60367 km and 54438 km, respectively. The equatorial and polar radius at 1 bar are given as 60268 km and 54364 km, respectively.
Lindal, et al., The Atmosphere Of Saturn: An Analysis Of The Voyager Radio Occultation Measurements. Astronomical J., 90, 1136-1146. (1985)
Cassini used the NAIF reference ellipsoid. The values used for the equatorial and polar radii for 1 bar are given as 60268 km and 54364 km, respectively. A reference sphere of 60330 km was also used for 100 mbar in the planning.
The shape of Saturn is more complex than what a simple ellipsoid represents. Engineering models used by the Cassini Project used gravitational parameters, zonal winds and rotation rates known at the time to generate a surface represented by a series of Legendre polynomials. Anderson...

Saturn Shape Data

Interior models/graphics should go here

Rotation Rate

Information on what we know of Saturn's unknown rotation rate can be found here. Key instruments contributing to this topic are: MAG, RPWS, RSS, and VIMS.

Key Review Books

    In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds) Cambridge University Press, 2018.
  • The mysterious periodicities of Saturn: Clues to the rotation rate of the planet. Carbary, J. F., Hedman, M. M., Hill, T. W., Jia, X., Kurth, W., Lamy, L., and Provan, G.

Key Review Publications

    Mankovich, C., et al., 2019. Cassini Ring Seismology as a Probe of Saturn's Interior. I. Rigid Rotation. Mankovich, C., et al., 2019. Astrophysical J., 871:1 (15pp). https://doi.org/10.3847/1538-4357/aaf798 Note: This study yielded a period of rotation of Saturn’s interior of P = 10h 33m 38s (+ 1m19s / -1m52s)

Atmospheric Properties

Sub-topics

Vertical Pressure and Temperature Structure Composition Zonal and Meridionial Temperature Fields Zonal Clouds and Haze Structure and Properties Seasonal Variation of Atmospheric Properties
Cassini conducted a unique multi-seasonal tour over 13 years that utilized an unprecedented range of viewing geometries and multi-wavelength studies to provide a plethora of new insights into the thermal, haze/cloud, and gaseous structure of the planet and their seasonal variability. The wide variety of orbital inclinations repeatedly achieved by the Cassini orbiter - from equatorial to nearly polar - provided direct and repeated viewing of all latitudes during the mission, from the poles to the equator by its broad array of synergistic instruments that spanned wavelengths from the UV to the far infrared. Science objectives included:
  • Determine temperature field, cloud properties, and composition of the atmosphere of Saturn.
  • Observe seasonal changes in the winds at all accessible altitudes coupled with simultaneous observations of clouds, temperatures, composition, and lightning.
  • Measure the spatial and temporal variability of trace gases and isotopes.
This section breaks these observations down into major sub-topics to help the user to focus in on what they might need.

Key Review Publications

      In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press, 2018.
    • Saturn's seasonally changing atmosphere: Thermal structure, composition and aerosols. Fletcher, L. N., Greathouse, T. K., Guerlet, S., Moses, J. I., and West, R. A.
    • Saturn's polar atmosphere. Sayanagi, K. M., Baines, K. H., Dyudina, U. A., Fletcher, L. N., Sanchez-Lavega, A., and West, R. A.

    Reference Data


    Saturn Segment Table

    The table below outlines the Saturn observation segments related to Saturn atmosphere by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations.
    Also available to download as [XLSX] or [CSV] Table of Time Periods with Atmospheric Property Observations
        Segment Times, Movies, Legacy Packages and Visualizations

    Vertical Pressure and Temperature Structure

    Information pertaining to the pressure (i.e., pressure vs. altitude) and temperature structure of Saturn's atmosphere are included in this section. Topics include UV and IR occultations and vertical and 3D temperature profiles. Key instruments contributing to this section are: CIRS, RSS, UVIS, and VIMS.

    Key Review Publications

    In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press, 2018.
    • Saturn Variable Thermosphere. pp. 224-250. Strobel, D.F., Koskinen, T.T., Müller-Wodarg, I.

    In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
    • Saturn Atmospheric Structure and Dynamics. pp. 113 -160. Del Genio, A.D., Achterberg, R.K., Baines, K.H., Flasar, F.M., Read, P.L., Sánchez-Lavega, A. and Showman, A.P.

    Vertical Pressure and Temperature Structure Data

    Composition

    Data sources and products relevant to the composition (both molecular and haze/cloud composition) of Saturn's atmosphere are included in this section. Key instruments contributing to this subject are CIRS, INMS, MIMI, RADAR, RSS, UVIS, and VIMS.

    Key Review Publications

    In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press, 2018.
    • Saturn’s Seasonally Changing Atmosphere. pp. 251-294. Fletcher, L.N., Greathouse, T.K., Guerlet, S., Moses, J.I., West, R.A.
      In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer 2009
    • Saturn: Composition and chemistry. pp. 83 -112. Fouchet, T., Moses, J. I., and Conrath, B. J.

    Additional Publications
    • Saturn's tropospheric composition and clouds from Cassini/VIMS 4.6-5.1 µm nightside spectroscopy. Icarus 214, 510-533
      Fletcher, L. N., Baines, K. H., Momary, T. W., Showman, A., Irwin, P. G. J., Orton, G. S., Roos-Serote, M., and Merlet, C. (2011).
    • Cloud clearing in the wake of Saturn's Great Storm of 2010-2011 and suggested new constraints on Saturn's He/H2 ratio. Icarus 276, 141-162
      Sromovsky, L. A., Baines, K. H., Fry, P. M., and Momary, T. W. (2016).

    Zonal and Meridonial Temperature Fields

    This section highlights the latitudinal and longitudinal temperature fields for noting seasonal variations and dynamical changes. Key instruments contributing to this section are: CIRS and VIMS.

    Key Review Publications

      In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
    • Saturn Atmospheric Structure and Dynamics. pp. 113 -160. Del Genio, A.D., Achterberg, R.K., Baines, K.H., Flasar, F.M., Read, P.L., Sánchez-Lavega, A. and Showman, A.P.


    Additional Publications
    • Thermal structure and dynamics of Saturn's northern springtime disturbance. Fletcher, L. N., Hesman, B. E., Irwin, P. G. J., Baines, K. H., Momary, T. W., Sanchez-Lavega, A., Flasar, F. M., Read, P. L., Orton, G. S., Simon-Miller, A., Hueso, R., Bjoraker, G., Marmoutkine. A, del Rio-Gaztelurrutia, T., Gomez, J. M., Brown, R. H., Buratti, B., Clark, R. N., Nicholson, P. D., and Sotin, C. (2011).

    Zonal and Meridionial Temperature Field Data

    Clouds and Haze: Zonal Structure and Properties

    This section highlights the data relevant to the zonal cloud and haze structure within Saturn's atmosphere. This includes both visual imaging and spectroscopic data. Key instruments contributing to this section are: ISS, UVIS, and VIMS.

    Key Review Publications

      In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
    • Clouds and aerosols in Saturn's atmosphere. pp. 161-179. West, R. A., Baines, K. H., Karkoschka, E., and Sánchez-Lavega, A.
      In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press 2018
    • The Great Storm of 2010-2011. Sánchez-Lavega, A., Fisher, G., Fletcher, L. N., García-Melendo, E., Hesman, B., Perez-Hoyos, S., Sayanagi, K. M., and Sromovsky, L. A.
    • Saturn's polar atmosphere. Sayanagi, K. M., Baines, K. H., Dyudina, U. A., Fletcher, L. N., Sánchez-Lavega, A., and West, R. A.

    Additional Publications
    • Saturn's thermal emission at 2.2-cm wavelength as imaged by the Cassini radar radiometer. Icarus 226, 522-535.
      Janssen, M. A., Ingersoll, A. P., Allison, M. D., Gulkis, S., Laraia, A. I., Baines, K. H., Edgington, S. G., Anderson, Y. Z., Kelleher, K., and Oyafuso, F. (2013).
    • Cloud features and zonal wind measurements of Saturn's atmosphere as observed by Cassini/VIMS. J. Geophys. Res. 114, E04007, doi:10.1029/2008JE003254
      Choi, D. S., Showman, A. P., and Brown, R. H. (2009).
    • Saturn's tropospheric composition and clouds from Cassini/VIMS 4.6-5.1 µm nightside spectroscopy. Icarus 214, 510-533
      Fletcher, L. N., Baines, K. H., Momary, T. W., Showman, A., Irwin, P. G. J., Orton, G. S., Roos-Serote, M., and Merlet, C. (2011).
    • Saturn's Great Storm of 2010-2011: Evidence for ammonia and water ices from analysis of VIMS spectra. Icarus 226, 402-418
      Sromovsky, L. A., Baines, K. H., and Fry, P. M. (2013).
    • Cloud clearing in the wake of Saturn's Great Storm of 2010-2011 and suggested new constraints on Saturn's He/H2 ratio. Icarus 276, 141-162
      Sromovsky, L. A., Baines, K. H., Fry, P. M., and Momary, T. W. (2016).

    Seasonal Variation of Atmospheric Properties

    Data relevant to seasonal variations within Saturn's atmosphere are included in this section. Some of the material included here will overlap with other sections on this website. Key instruments contributing to this subject section are: CIRS, ISS, RSS, UVIS, and VIMS.

    Key Publications

        In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press, 2018.
      • Saturn’s Seasonally Changing Atmosphere. pp. 251-294. Fletcher, L.N., Greathouse, T.K., Guerlet, S., Moses, J.I., West, R.A.
            • In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
          • Saturn Atmospheric Structure and Dynamics. ppp. 113 -160. Del Genio, A.D., Achterberg, R.K., Baines, K.H., Flasar, F.M., Read, P.L., Sánchez-Lavega, A. and Showman, A.P.

    Global Circulation and Dynamics

    Sub-topics

    Zonal Winds Global Circulation and Convection Seasonal Variation of Global Circulation and Dynamics Polar Regions 2010-2012 Great Storm
    Repeated multi-wavelength observations over a single or sometimes several rotations by ISS and VIMS allowed the motions of clouds to be measured, resulting in direct measurements of zonal winds at various altitudes that could be compared to the thermal wind structure derived from the temperature field measured by CIRS. Such observations were repeated throughout the 13-year orbital mission, providing insights into the seasonal variability of the zonal winds and their associated zonal wind shears.
    The polar regions - including the uniquely shaped North Polar Hexagon - and the Great Storm of 2010-2011 provided fundamental new insights into the global circulation and local meteorology of the planet. Science objectives included:
    • Measure the global wind field, including wave and eddy components; observe synoptic cloud features and processes.
    • Investigate the sources and the morphology of Saturn lightning (Saturn Electrostatic Discharges (SED), lightning whistlers).
    • Observe seasonal changes in the winds at all accessible altitudes coupled with simultaneous observations of clouds, temperatures, composition, and lightning.
    • Observe the aftermath of the 2010-2011 storm. Study the life cycles of Saturn's newly discovered atmospheric waves, south polar hurricane, and rediscovered north polar hexagon.
    • Monitor the planet for new storms and respond with new observations when the new storms occur.

    Key Review Publications

      In Saturn (Gehrels, T., Matthews, M. S, eds). Univ. Arizona Press, Tucson. (1984)
    • Structure and dynamics of Saturn's atmosphere. pp. 195-238. Ingersoll, A. P., Beebe, R. F., Conrath, B. J., and Hunt, G. E.
      In Saturn from Cassini-Huygens (M. K. Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
    • Saturn atmospheric structure and dynamics, pp. 113-159. Del Genio, A. D., Achterberg, R. K., Baines, K. H., Flasar, F. M., Read, P. L., Sánchez-Lavega, A., and Showman, A. P.
      In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press. in press. (2018)
    • The global atmospheric circulation of Saturn. Showman, A. P., Ingersoll, A. P., Achterberg, R., and Kaspi. Y.

    Reference Data


    Saturn Segment Table

    The table below outlines the Saturn observation segments related to Saturn's Dynamics by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations.
    Also available to download as [XLSX] or [CSV] Table of Time Periods with Circulation and Dynamics Observations
        Segment Times, Movies, Legacy Packages and Visualizations

    Zonal Winds

    Determination of zonal wind speeds at various pressure levels in the atmosphere are included in this section. Key instruments that contributed to this topic are: ISS, VIMS and CIRS.

    Key Publications

    In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
    • Saturn Atmospheric Structure and Dynamics. pp. 113 -160. Del Genio, A.D., Achterberg, R.K., Baines, K.H., Flasar, F.M., Read, P.L., Sánchez-Lavega, A. and Showman, A.P.
    Additional Publications
    • Cloud features and zonal wind measurements of Saturn's atmosphere as observed by Cassini/VIMS. J. Geophys. Res. 114, E04007, Choi, D. S., Showman, A. P., and Brown, R. H. (2009). doi:10.1029/2008JE003254
    • Saturn's zonal wind profile in 2004–2009 from Cassini ISS images and its long-term variability. Icarus, 215, 62-74, García-Melendo, E., S. Pérez-Hoyos, A. Sánchez-Lavega, R. Hueso (2011).
    • Saturn's Global Zonal Winds Explored by Cassini/VIMS 5-µm Images. Geophysical Research Letters, 45, 6823-6831. Studwell A., L. Li , X. Jiang , K.H. Baines , P.M. Fry, T.W. Momary , and U.A. Dyudina (2018) doi:10.1029/2018GL078139

    Wind Data

    Zonal Winds vs. Latitude (ISS) The zonal winds provided below from the analysis of Garcia-Melendo, et al. (2011) Zonal Winds at 2 bars vs. Latitude (VIMS) See Saturn’s Global Zonal Winds Explored by Cassini/Vims 5μ Images, A Studwell, et al., Geophysical Research Letters, Volume 45, Issue 14, pp. 6823 - 6831, DOI 10.1029/2018GL078139

    Global Circulation and Convection

    Global circulation and energy budget of Saturn's atmosphere are included in this section. Instruments contributing to this study are: CIRS, ISS, UVIS, VIMS.

    Key Review Publications

    In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press. in press. (2018)
  • The global atmospheric circulation of Saturn. Showman, A. P., Ingersoll, A. P., Achterberg, R., and Kaspi. Y.
In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • Saturn Atmospheric Structure and Dynamics. pp. 113 -160. Del Genio, A.D., Achterberg, R.K., Baines, K.H., Flasar, F.M., Read, P.L., Sánchez-Lavega, A. and Showman, A.P.

Additional Publications
  • Constraints on Saturn's tropospheric general circulation from Cassini ISS images. Icarus, 219, 689-700. Del Genio, A. D., and Barbara, J. M., (2012).
  • Emitted power of Jupiter based on Cassini CIRS and VIMS observations. JGR-Planets, doi:10.1029/2012JE004191
    Li, L., Baines, K. H., Smith, M. A., West, R. A., Pérez-Hoyos, S., Trannell, H. J., Simon-Miller, A. A., Conrath, B. J., Orton, G. S., Nixon, C. A., Filacchione, G., Fry, P,. M., and Momary, T. W (2012)
  • Cassini imaging science: Initial results on Saturn's atmosphere. Science 307, 1243-1247. Porco, C. C. et al. (2005).
  • Cassini imaging of Saturn: Southern-hemisphere winds and vortices. J. Geophys. Res., 111, E05004(E10), 1-13. Vasavada, A. R., Hörst, S. M., Kennedy, M. R., Ingersoll, A. P., Porco, C. C., Del Genio, A. D. and West, R. A. (2006).
  • Saturn momentum fluxes and convection: First estimates from Cassini images. Icarus 189, 479-492 Del Genio, A. D. et al. (2007)

Seasonal Variation of Global Circulation and Dynamics

Many changes in the visible atmosphere of Saturn can be traced back to seasonal variations. This section focuses on its attention on solar and seasonally driven phenomena. Instruments contributing to this study are: CIRS, ISS, UVIS, VIMS.

Key Publications

In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • Saturn Atmospheric Structure and Dynamics. pp. 113 -160. Del Genio, A.D., Achterberg, R.K., Baines, K.H., Flasar, F.M., Read, P.L., Sánchez-Lavega, A. and Showman, A.P.

Polar Regions

Dynamics and phenomena occurring near the vicinity of both north and south poles of the planet are included in this section. Instruments contributing to this study are: CIRS, ISS, UVIS, VIMS.

Key Review Publications

    In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press. in press. (2018)
    • Saturn's polar atmosphere. Sayanagi, K. M., Baines, K. H., Dyudina, U. A., Fletcher, L. N., Sanchez-Lavega, A., and West, R. A.

Additional Publications
  • Cassini ISS observation of Saturn’s north polar vortex and comparison to the south polar vortex.. Icarus 202, 240-248. Sayanagi, K. M., Blalock, J. J., Dyudina, U. A., Ewald, S. P., and Ingersoll, A. P. (2009).
  • Saturn's north polar cyclone and hexagon at depth revealed by Cassini/VIMS. Planetary and Space Sci. 57, 1671-1681. doi:10.1016/j.pss.2009.06.026 Baines, K. H., Momary, T. W., Fletcher, L. N., Showman, A. P., Roos-Serote, M., Brown, R. H., Buratti, B. J., Clark, R. N., and Nicholson, P. D. (2009).
  • Saturn's south pole vortex compared to other large vortices in the solar system. Icarus 202, 240-248. Dyudina, U. A., Ingersoll, A. P., Ewald, S. P., Vasavada, A. R., West, R. A., Baines, K. H., Momary, T. W., Del Genio, A. D., Barbara, J. M., Porco, C. C., Achterberg. R. K., Flasar, F. M., Simon-Miller, A. A., and Fletcher, L. N. (2009).

2010-2012 Great Storm

Once every 20-30 years, Saturn erupts with planet-wide storms. Cassini was there to see this rare event up-close and personal. Instruments contributing to this study are: CIRS, ISS, RADAR, RPWS, UVIS, VIMS.

Derived data

   Measurements of CH4 and H2 were used to retrieve temperature profiles inside the storm region.

Key Publications

    In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press. in press. (2018)
    • The Great Storm of 2010-2011. Sánchez-Lavega, A., Fisher, G., Fletcher, L. N., García-Melendo, E., Hesman, B., Perez-Hoyos, S., Sayanagi, K. M., and Sromovsky, L. A.

Additional Publications
  • Saturn's Great Storm of 2010-2011: Evidence for ammonia and water ices from analysis of VIMS spectra. Icarus 226, 402-418
    Sromovsky, L. A., Baines, K. H., and Fry, P. M. (2013).
  • Cloud clearing in the wake of Saturn's Great Storm of 2010-2011 and suggested new constraints on Saturn's He/H2 ratio. Icarus 276, 141-162
    Sromovsky, L. A., Baines, K. H., Fry, P. M., and Momary, T. W. (2016).
  • Dynamics of Saturn's great storm of 2010-2011 from Cassini ISS and RPWS. Icarus, 223, 460-478. Sayanagi, K. M., Dyudina, U. A., Ewald, S. P., Fischer, G., Ingersoll, A. P., Kurth, W. S., Muro, G. D., Porco, C. C., and West, R. A. (2013).
  • Cassini ISS observation of Saturn's string of pearls. Icarus, 229, 170-180. Sayanagi, K. M., U. A. Dyudina, U. A., S. P. Ewald, S. P., G. D. Muro, G. D., and Ingersoll, A. P. (2014).
  • Thermal structure and dynamics of Saturn's northern springtime disturbance. Science 332, 1413-1417. Fletcher, L. N., Hesman, B. E., Irwin, P. G. J., Baines, K. H., Momary, T. W., Sanchez-Lavega, A., Flasar, F. M., Read, P. L., Orton, G. S., Simon-Miller, A., Hueso, R., Bjoraker, G., Marmoutkine. A, del Rio-Gaztelurrutia, T., Gomez, J. M., Brown, R. H., Buratti, B., Clark, R. N., Nicholson, P. D., and Sotin, C. (2011).

Auroral Observations

Auroras on Saturn occur in a process similar to Earth's northern and southern lights. Particles from the solar wind are channeled by Saturn's magnetic field toward the planet's poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. At Saturn, however, auroral features can also be caused by electromagnetic waves generated when the planet's moons move through the plasma that fills Saturn's magnetosphere.

Science objectives includes

  • Observe the magnetosphere, ionosphere, and aurora as they change on all time scales—minutes to years—and are affected by seasonal and solar cycle forcing. Here the focus is on contributions from optical remote sensing instruments: CIRS, ISS, UVIS, and VIMS.

Key Review Publications

    In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • Auroral Processes. pp. 333-374. Kurth, W.S., Bunce, E.J., Clarke, J.T., Crary, F.J., Grodent, D.C., Ingersoll, A.P., Dyudina, U.A., Lamy, L., Mitchell, D.G., Persoon, A.M., Pryor, W.R., Saur, J., and Stallard, T.
    In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press. (2018)
  • Saturn's Aurora. Stallard, T., Badman, S., Dyudina, U., Grodent, D., and Lamy, L.

Additional Publications
  • Auroral Storm and Polar Arcs at Saturn—Final Cassini/UVIS Auroral Observations. Palmaerts, B., Radioti, A., Grodent, D., Yao, Z. H., Bradley, T. J., Roussos, E., Lamym, L., Bunce, E.J. , Cowley, S.W.H., Krupp, N., Kurth, W.S., Gérard, J.-C., Pryor, W.R. . Geophysical Research Letters, 45, 6832-6842, 2018 https://doi.org/10.1029/2018GL078094
  • Saturn’s northern aurorae at solstice from HST observations coordinated with Cassini’s grand finale. Lamy, L., Prangé, R., Tao, C., Kim, T., Badman, S. V., Zarka, P., Cecconi, B., Kurth, W.S., Pryor, W., Bunce, E., and Radioti, A. Geophysical Research Letters, 45, 9353–9362, 2018. https://doi.org/10.1029/2018GL078211
  • Complex structure within Saturn's infrared aurora. Nature, 456, 214-216. Stallard, T., Miller, S., Lystrup, M., Achilleos, N., Bunce, E. J., Arridge, C. S., Dougherty, M. K., Cowley, S. W. H., Badman, S. V., Talboys, D. L., Brown, R. H., Baines, K. H., Buratti, B. J., Clark, R. N., Sotin, C. S., Nicholson, P. D., and Drossart, P. D. (2008).
  • Cassini VIMS observations of latitudinal and hemispheric variations in Saturn's infrared auroral intensity. Icarus 216, 367-375., doi:10.1016/j.icarus.2011.09.031
    Badman, S. V., Tao, C., Grocott, A., Kasahara, S., Melin, H., Brown, R. H., Baines, K. H., Fujimoto, M., and Stallard, T. (2011).

Auroral Data

Auroral Observation Reference Tables

Processed data

Reference Data


Saturn Segment Table

The table below outlines the Saturn observation segments related to Saturn Aurorae by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations.
Also available to download as [XLSX] or [CSV] Table of Time Periods with Auroral Observations
    Segment Times, Movies, Legacy Packages and Visualizations

Ancillary Data

  • The Magnetospheric Science page references a variety of magnetic field models, which may be used in conjunction with the remote-sensing measurements to relate the interactions of ions with the magnetic field.
  • SPICE geometry information is important to correct the alignment of the atmosphere with the observations and with alignment to the magnetic field lines. When performing an analysis of Aurorae, it is may be useful to visualize the visible-spectra data with SPICE geometry data in order to align the data with Saturn's atmosphere. The built-in backplane (geometry) data for some data sets like VIMS can be made more accurate using SPICE to indicate the atmospheric "height" from the typical one-bar surface.

Ionosphere and Magnetic Fields

This section focuses on observations of the ionosphere and magnetic field and subsequent plasma measurements. Key instruments contributions made by INMS, MAG, MIMI, RPWS, RSS.
Cassini has a variety of instruments to study Saturn's magnetic field and associated plasma interactions. Information on ionosphere studies can be found below; please see the Cassini Magnetospheric Science page for other information.

Mission Objective

  • Study the diurnal variations and magnetic control of the ionosphere of Saturn.

Key Publications

    In Saturn from Cassini-Huygens (M.Dougherty, L. W. Esposito, and S. M. Krimigis, Eds). Springer (2009)
  • Upper atmosphere and ionosphere of Saturn. pp. 181-291. Nagy, A. F., Kliore, A. J., Mendillo, M., Miller, S., Moore, L., Moses, J. I., Müller-Wodarg, I., and Shemansky, D.
    In Saturn in the 21st Century (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds). Cambridge University Press 2018
  • Saturn's ionosphere. Moore, L., Galand, M., Kliore, A. J., Nagy, A. F., and O'Donoghue, J.
  • Saturn's variable thermosphere. Strobel, D. F., Koskinen, T., and Müller-Wodarg, I.

Additional Publications
  • The domination of Saturn's low latitude ionosphere by ring rain. Nature 496, 193-195. O'Donoghue, J., Stallard, T. S., Melin, H., Jones, G. H., Cowley, S. W. H., Miller, S., Baines, K. H., and Blake, J. S. D. (2013).

Derived Data

Ancillary Data

  • The Magnetic Field Model [CSV download] is used in conjunction with the optical measurements to relate the interactions of ions with the magnetic field.
  • SPICE geometry information is important to correct the alignment of the atmosphere with the observations and with alignment to the magnetic field lines.

Reference Data

  • Observations from Saturn Observation Guide [CSV]
  • Event Calendar provides a search interface to find Saturn observations focused on Saturn Ionosphere and Magnetosphere, or other science topics

Saturn Segment Table

The table below outlines the Saturn observation segments related to Saturn's Ionosphere and Magnetosphere by name, start time, and end time, with links to segment movies (where available), legacy packages, and timeline visualizations.
Also available to download as [XLSX] or [CSV] Table of Time Periods with Ionosphere and Magnetosphere Observations
    Segment Times, Movies, Legacy Packages and Visualizations

Ionosphere Structure

Materials related to ionospheric structure can be found here. The key instruments contributing to this subject are: RSS and UVIS

A Key Publication

    In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds) Cambridge University Press, 2018.
  • Saturn’s Ionosphere. L Moore, M. Galand, A.J. Kliore, A.F. Nagy, J. O’Donogue.

The ionospheres – thermospheres of the giant planets. Majeed, T., J. Waite, S. Bougher, R. Yelle, G. Gladstone, J. McConnell, and A. Bhardwaj, Adv. Sp. Res., 33(2), 197–211, 2004 https://doi:10.1016/j.asr.2003.05.009.

Additional Publications
    In Saturn, University of Arizona Press, Tucson, AZ, 1984.
  • Theory, measurements, and models of the upper atmosphere and ionosphere of Saturn, Atreya, S. K., T. M. Donahue, A. F. Nagy, J. H. Waite Jr., and J. C. McConnell, pp. 239–277.

The ionospheres–thermospheres of the giant planets. Majeed, T., J. Waite, S. Bougher, R. Yelle, G. Gladstone, J. McConnell, and A. Bhardwaj, Adv. Sp. Res., 33(2), 197–211, 2004 https://doi:10.1016/j.asr.2003.05.009.

In Jupiter: The Planet, Satellites and Magnetosphere, edited by F. Bagenal, T. E. Dowling, and W. B. McKinnon, Cambridge University Press, Cambridge. 2010.
  • Jupiter’s Thermosphere and Ionosphere Yelle, R. V, and S. Miller , pp. 185–218

In Saturn from Cassini-Huygens, edited by M. K. Dougherty, L. W. Esposito, and S. M. Krimigis, pp. 181–201, Springer Netherlands, Dordrecht, 2009.
  • Upper Atmosphere and Ionosphere of Saturn, Nagy, A. F., A. J. Kliore, M. Mendillo, S. Miller, L. Moore, J. I. Moses, I. Müller-Wodarg, and D. Shemansky , pp. 181–201.

In Ionospheres:Physics, Plasma Physics, and Chemistry, 2nd ed., Cambridge University Press, Cambridge, UK, 2009/
  • Upper Atmosphere and Ionosphere of Saturn, Schunk, R. W., and A. F. Nagy, pp. 181–201

Magnetic Field Structure

Materials related to the formation and subsequent morphology of Saturn's interior magnetic field can be found here. The key instrument contributing to this subject is: MAG.

Key Review Publications

    In Saturn in the 21st Century. (K. H. Baines, F. M. Flasar, N. Krupp, T. Stallard, Eds) Cambridge University Press, 2018.
  • The mysterious periodicities of Saturn: Clues to the rotation rate of the planet. Carbary, J. F., Hedman, M. M., Hill, T. W., Jia, X., Kurth, W., Lamy, L., and Provan, G.
  • Saturn's magnetic field and dynamo. Christensen, U. R., Cao, H., Dougherty, M., Khurana, K.
  • Model of Saturn's internal planetary magnetic field based on Cassini observations. Burton, M.E., M.K. Dougherty, and C.T. Russell. Planetary and Space Sciences, 57, 1706-1713. (2009)
  • Saturn's magnetic field revealed by the Cassini Grand Finale Dougherty, M.K., H. Cao, K.K. Khurana, G.J. Hunt, G. Provan, S. Kellock, M.E. Burton, T.A. Burk, E.J. Bunce, S.W.H. Cowley, M.G. Kivelson, C.T. Russell, D.J. Southwood, Science, 362, Issue 6410, id.aat5434 (2018) [DOI: 10.1126/science.aat5434]

Interior Magnetic Field Data

Ƒrom Saturn's magnetic field revealed by the Cassini Grand Finale, Dougherty, M.K., H. Cao, K.K. Khurana, G.J. Hunt, G. Provan, S. Kellock, M.E. Burton, T.A. Burk, E.J. Bunce, S.W.H. Cowley, M.G. Kivelson, C.T. Russell, D.J. Southwood, Science, 362, Issue 6410, id.aat5434 (2018) [DOI: 10.1126/science.aat5434]

Table 1 Gauss coefficients of a new model for Saturn’s internal magnetic field, which we refer to as the Cassini 11 model, constructed from nine orbits of Cassini Grand Finale MAG data with regularized inversion.

The reported uncertainty is five times the formal uncertainties associated with the chosen regularization (Methods).
Gauss coefficientValue (nT)Uncertainty (nT)
g1021140.21
g201581.11.2
g302260.13.2
g4091.14.2
g5012.67.1
g6017.28.2
g70–59.68.1
g80–10.58.7
g90–12.96.3
g100157
g11018.27.1
g1200.37.7
RMS residual6.2


In the Research Article “Saturn’s magnetic field revealed by the Cassini Grand Finale,” a copyediting error led to the inadvertent omission of the sign of the value for Gauss coefficient g70 in Table 1 online. The correct value is –59.6. The online version has been corrected. In addition, the authors corrected three supplementary figure callouts on p. 6 and an in-text citation on p. 7.

For questions and comments, visit the PDS Cassini Contact Page