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Imaging of Titan from the Cassini spacecraft

Abstract

Titan, the largest moon of Saturn, is the only satellite in the Solar System with a substantial atmosphere. The atmosphere is poorly understood and obscures the surface, leading to intense speculation about Titan's nature. Here we present observations of Titan from the imaging science experiment onboard the Cassini spacecraft that address some of these issues. The images reveal intricate surface albedo features that suggest aeolian, tectonic and fluvial processes; they also show a few circular features that could be impact structures. These observations imply that substantial surface modification has occurred over Titan's history. We have not directly detected liquids on the surface to date. Convective clouds are found to be common near the south pole, and the motion of mid-latitude clouds consistently indicates eastward winds, from which we infer that the troposphere is rotating faster than the surface. A detached haze at an altitude of 500 km is 150–200 km higher than that observed by Voyager, and more tenuous haze layers are also resolved.

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Figure 1: Albedo map of Titan's surface.
Figure 2: Images of Titan's south polar region.
Figure 3: Mosaic of the equatorial region of Titan's anti-saturnian hemisphere.
Figure 4: Locations of specular point observations on Titan's anti-saturnian hemisphere.
Figure 5: Full-disk image of Titan showing Xanadu Regio.
Figure 6: High-resolution views of Titan's surface.
Figure 7: Tropospheric cloud features on Titan.
Figure 8: South polar clouds seen at different wavelengths.
Figure 9: Cloud-tracked wind speeds versus latitude on Titan.
Figure 10: Images of Titan's stratospheric haze layers.
Figure 11: Intensity profiles of Titan's detached haze layer at varying latitudes.
Figure 12: Multiple haze layers in Titan's north polar hood.

References

  1. Porco, C. C. et al. Cassini imaging science: Instrument characteristics and anticipated scientific investigations at Saturn. Space Sci. Rev. 115, 363–497 (2004)

    ADS  Article  Google Scholar 

  2. McKay, C. P. et al. Temperature lapse rate and methane in Titan's troposphere. Icarus 129, 498–505 (1997)

    ADS  CAS  Article  Google Scholar 

  3. Samuelson, R. E., Nath, N. R. & Borysow, A. Gaseous abundances and methane supersaturation in Titan's troposphere. Planet. Space Sci. 45, 959–980 (1997)

    ADS  CAS  Article  Google Scholar 

  4. Lunine, J. I. & Soderblom, L. A. Cassini-Huygens investigations of satellite surfaces and interiors. Space Sci. Rev. 104, 191–208 (2002)

    ADS  CAS  Article  Google Scholar 

  5. Khare, B. N., Sagan, C., Bandurski, E. L. & Nagy, B. Ultraviolet-photoproduced organic solids synthesized under simulated jovian conditions: Molecular analysis. Science 199, 1199–1201 (1978)

    ADS  CAS  Article  Google Scholar 

  6. Lunine, J. I., Stevenson, D. J. & Yung, Y. L. Ethane ocean on Titan. Science 222, 1229–1230 (1983)

    ADS  CAS  Article  Google Scholar 

  7. Smith, P. H., Lemmon, M. T. & Lorenz, R. D. Titan's surface, revealed by HST imaging. Icarus 119, 336–349 (1996)

    ADS  Article  Google Scholar 

  8. Coustenis, A. et al. Images of Titan at 1.3 and 1.6 µm with adaptive optics at the CFHT. Icarus 154, 501–515 (2001)

    ADS  CAS  Article  Google Scholar 

  9. Gibbard, S. G. et al. Speckle imaging of Titan at 2 microns: surface albedo, haze optical depth, and tropospheric clouds. Icarus 169, 429–439 (2004)

    ADS  CAS  Article  Google Scholar 

  10. Griffith, C. A. et al. Transient clouds in Titan's lower atmosphere. Nature 395, 575–578 (1998)

    ADS  CAS  Article  Google Scholar 

  11. Rages, K. & Pollack, J. B. Vertical distribution of scattering hazes in Titan's upper atmosphere. Icarus 55, 50–62 (1983)

    ADS  Article  Google Scholar 

  12. Raulin, F. & Owen, T. Organic chemistry and exobiology on Titan. Space Sci. Rev. 104, 377–394 (2002)

    ADS  CAS  Article  Google Scholar 

  13. Richardson, J., Lorenz, R. D. & McEwen, A. Titan's surface and rotation—New insights from Voyager images. Icarus 170, 113–124 (2004)

    ADS  Article  Google Scholar 

  14. Griffith, C. A., Owen, T. & Wagener, R. Titan's surface and troposphere, investigated with ground-based, near-infrared observations. Icarus 93, 362–378 (1991)

    ADS  CAS  Article  Google Scholar 

  15. Brown, M. E., Bouchez, A. H. & Griffith, C. A. Direct detection of tropospheric clouds near Titan's south pole. Nature 420, 795–797 (2002)

    ADS  CAS  Article  Google Scholar 

  16. Bouchez, A. et al. Keck Observatory Titan monitoring project. http://www2.keck.hawaii.edu/science/titan/ (2005).

  17. Perron, J. T. & de Pater, I. Dynamics of an ice continent on Titan. Geophys. Res. Lett. 31, doi:10.1029/2004GL019802 (2004)

  18. Lorenz, R. D. & Lunine, J. I. Titan's surface before Cassini. Planet. Space Sci. (in the press) (2005)

  19. Griffith, C. A. et al. Evidence for exposure of water ice on Titan's surface. Science 300, 628–630 (2003)

    ADS  CAS  Article  Google Scholar 

  20. Campbell, D. B. et al. Radar evidence for liquid surfaces on Titan. Science 302, 431–434 (2003)

    ADS  CAS  Article  Google Scholar 

  21. Lunine, J. I. Does Titan have an ocean? A review of current understanding of Titan's surface. Rev. Geophys. 31, 133–150 (1993)

    ADS  Article  Google Scholar 

  22. Lorenz, R. D. Crater lakes on Titan: rings, horseshoes, and bullseyes. Planet. Space Sci. 42, 1–4 (1994)

    ADS  Article  Google Scholar 

  23. Zahnle, K., Schenk, P., Levison, H. & Dones, L. Cratering rates in the outer Solar System. Icarus 163, 263–289 (2003)

    ADS  Article  Google Scholar 

  24. Dobrovolskis, A. R. & Lissauer, J. J. Fate of ejecta from Hyperion. Icarus 169, 462–473 (2004)

    ADS  Article  Google Scholar 

  25. Croft, S. K., Lunine, J. L. & Kargel, J. Equation of state of ammonia-water liquid—Derivation and planetological applications. Icarus 73, 279–293 (1988)

    ADS  CAS  Article  Google Scholar 

  26. Tokano, T. & Neubauer, F. M. Tidal winds on Titan caused by Saturn. Icarus 158, 499–515 (2002)

    ADS  Article  Google Scholar 

  27. Strobel, D. F. Chemistry and evolution of Titan's atmosphere. Planet. Space Sci. 30, 839–848 (1982)

    ADS  CAS  Article  Google Scholar 

  28. Dimitrov, V. & Bar-Nun, A. Hardening of Titan's aerosols by their charging. Icarus 166, 440–443 (2003)

    ADS  CAS  Article  Google Scholar 

  29. Hourdin, F. et al. Numerical simulation of the general circulation of the atmosphere of Titan. Icarus 117, 358–374 (1995)

    ADS  CAS  Article  Google Scholar 

  30. Rannou, P. et al. A coupled dynamics-microphysics model of Titan's atmosphere. Icarus 170, 443–462 (2004)

    ADS  Article  Google Scholar 

  31. Lemmon, M. T. et al. HST observations of Titan, 1994–1997: New surface albedo maps and detection of large-scale, sub-tropical cloud activity. Icarus (submitted)

  32. Roe, H. G. et al. Discovery of temperate latitude clouds on Titan. Astrophys. J. 618, L49–L52 (2005)

    ADS  Article  Google Scholar 

  33. Rossow, W. B., Del Genio, A. D. & Eichler, T. P. Cloud-tracked winds from Pioneer Venus OCPP images. J. Atmos. Sci. 47, 2053–2084 (1990)

    ADS  Article  Google Scholar 

  34. Flasar, F. M., Samuelson, R. E. & Conrath, B. J. Titan's atmosphere: Temperature and dynamics. Nature 292, 693–698 (1981)

    ADS  Article  Google Scholar 

  35. Del Genio, A. D., Zhou, W. & Eichler, T. P. Equatorial superrotation in a slowly rotating GCM: Implications for Titan and Venus. Icarus 101, 1–17 (1993)

    ADS  Article  Google Scholar 

  36. Del Genio, A. D. & Zhou, W. Simulations of superrotation on slowly rotating planets: Sensitivity to rotation and initial condition. Icarus 120, 332–343 (1996)

    ADS  Article  Google Scholar 

  37. Allison, M., Del Genio, A. D. & Zhou, W. Zero potential vorticity envelopes for the zonal-mean velocity of the Venus/Titan atmospheres. J. Atmos. Sci. 51, 694–702 (1994)

    ADS  Article  Google Scholar 

  38. Lemmon, M., Smith, P. & Lorenz, R. The evolution of Titan's polar hood near summer solstice. 35th COSPAR Scientific Assembly (Paris, 18–25 July 2004) abstr. COSPAR04-A-04048 (2004)

    Google Scholar 

  39. Hutzell, W. T. et al. Simulations of Titan's brightness by a two-dimensional haze model. Icarus 119, 112–129 (1995)

    ADS  Article  Google Scholar 

  40. Hinson, D. P. & Tyler, G. L. Internal gravity waves in Titan's atmosphere observed by Voyager radio occultation. Icarus 54, 337–352 (1983)

    ADS  Article  Google Scholar 

  41. Friedson, A. J. Gravity waves in Titan's atmosphere. Icarus 109, 40–57 (1994)

    ADS  Article  Google Scholar 

  42. Sicardy, B. et al. The structure of Titan's stratosphere from the 28 Sgr occultation. Icarus 142, 357–390 (1999)

    ADS  Article  Google Scholar 

  43. Korycansky, D. G. & Zahnle, K. J. Modeling crater populations on Venus and Titan. Planet. Space Sci. (in the press)

  44. West, R. A. & Smith, P. H. Evidence for aggregate particles in the atmospheres of Titan and Jupiter. Icarus 90, 330–333 (1991)

    ADS  CAS  Article  Google Scholar 

  45. Sotin, C. et al. Cassini VIMS observations during the October 2004 flyby of Titan: Clues to the dynamics of Titan's surface. Nature (submitted)

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Acknowledgements

We acknowledge the many members of the imaging team who have assisted in the design of imaging sequences and camera commands and in other vital operational and image processing tasks, in particular N. Martin, E. Birath, J. Riley, B. Knowles, C. Clark, M. Belanger and D. Wilson. This work has been funded by NASA/JPL, the UK Particle Physics and Astronomy Research Council, the German Aerospace Center (DLR), and Université Paris VII Denis Diderot, CEA, AIM, France.

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Correspondence to Carolyn C. Porco.

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Porco, C., Baker, E., Barbara, J. et al. Imaging of Titan from the Cassini spacecraft. Nature 434, 159–168 (2005). https://doi.org/10.1038/nature03436

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