Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Compositional maps of Saturn's moon Phoebe from imaging spectroscopy

Abstract

The origin of Phoebe, which is the outermost large satellite of Saturn, is of particular interest because its inclined, retrograde orbit suggests that it was gravitationally captured by Saturn, having accreted outside the region of the solar nebula in which Saturn formed1. By contrast, Saturn's regular satellites (with prograde, low-inclination, circular orbits) probably accreted within the sub-nebula in which Saturn itself formed2. Here we report imaging spectroscopy of Phoebe resulting from the Cassini–Huygens spacecraft encounter on 11 June 2004. We mapped ferrous-iron-bearing minerals, bound water, trapped CO2, probable phyllosilicates, organics, nitriles and cyanide compounds. Detection of these compounds on Phoebe makes it one of the most compositionally diverse objects yet observed in our Solar System. It is likely that Phoebe's surface contains primitive materials from the outer Solar System, indicating a surface of cometary origin.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: VIMS data, x and y axes show longitude and latitude, respectively, in degrees.
Figure 2: Spectra of Phoebe show the presence of numerous compounds.

Similar content being viewed by others

References

  1. Pollack, J. B. et al. Gas drag in primordial circumplanetary envelopes: A mechanism for satellite capture. Icarus 37, 587–611 (1979)

    Article  ADS  Google Scholar 

  2. Burns, J. A. in Satellites (eds Burns, J. A. & Matthews, M. S.) 117–158 (Univ. Arizona Press, Tucson, 1986)

    Google Scholar 

  3. Brown, R. H. et al. The Cassini Huygens Mission. Space Sci. Rev. (in the press)

  4. Owen, T. C. et al. Detection of water ice on Saturn's satellite Phoebe. Icarus 139, 379–382 (1999)

    Article  ADS  CAS  Google Scholar 

  5. Liou, J. C. & Malhotra, R. Depletion of the outer asteroid belt. Science 275, 375–377 (1997)

    Article  ADS  CAS  Google Scholar 

  6. Levison, H. F. & Morbidelli, A. The formation of the Kuiper belt by the outward transport of bodies during Neptune's migration. Nature 426, 419–421 (2003)

    Article  ADS  CAS  Google Scholar 

  7. Brown, R. H., Cruikshank, D. P. & Pendleton, Y. J. Water ice on Kuiper Belt object 1996 TO66 . Astrophys. J. Lett. 519, 101–104 (1999)

    Article  ADS  Google Scholar 

  8. Barucci, M. A. et al. Analysis of Trans-Neptunian and Centaur colours: continuous trend or grouping? Astron. Astrophys. 371, 1150–1154 (2001)

    Article  ADS  Google Scholar 

  9. Buratti, B. J., Hicks, M. D., Tryka, K. A., Sittig, M. S. & Newburn, R. L. High-resolution 0.33–0.92 µm spectra of Iapetus, Hyperion, Phoebe, Rhea, Dione, and D-type asteroids: How are they related? Icarus 155, 375–381 (2002)

    Article  ADS  CAS  Google Scholar 

  10. Jarvis, K. S., Vilas, F., Larson, S. M. & Gaffey, M. J. Are Hyperion and Phoebe linked to Iapetus? Icarus 146, 125–132 (2000)

    Article  ADS  CAS  Google Scholar 

  11. McCord, T. B. et al. Non-water-ice constituents in the surface material of the icy Galilean satellites from Galileo Near-Infrared Mapping Spectrometer investigation. J. Geophys. Res. 103, 8603–8626 (1998)

    Article  ADS  CAS  Google Scholar 

  12. Clark, R. N. et al. The U.S. Geological Survey, Digital Spectral Library splib05 (Open File Report 03-395, USGS, Denver, 2003); 〈http://speclab.cr.usgs.gov/spectral-lib.html

    Google Scholar 

  13. Hook, S. ASTER Spectral Library (Jet Propulsion Laboratory, Pasadena, 2004); 〈http://speclib.jpl.nasa.gov

    Google Scholar 

  14. Buratti, B. J. et al. Iapetus: First data from the Cassini Visual Infrared Mapping Spectrometer. Bull. Am. Astron. Soc. 36, 1072 (2004)

    ADS  Google Scholar 

  15. Soderblom, L. A. et al. Observations of comet 19P/Borrelly by the Miniature Integrated Camera and Spectrometer aboard Deep Space 1. Science 296, 1087–1091 (2002)

    Article  ADS  CAS  Google Scholar 

  16. Stein, S. E. NIST Standard Reference Database 35. NIST Spectral Library (National Institute of Standards and Technology, Gaithersburg, Maryland, 2004); 〈http://www.nist.gov/srd/nist35.htm〉.

  17. Gaffey, M. J. Forging an asteroid-meteorite link. Science 260, 167–168 (1993)

    Article  ADS  CAS  Google Scholar 

  18. Cruikshank, D. P. et al. Search for 3.4-µm C-H spectral bands on low albedo asteroids. Icarus 156, 434–441 (2002)

    Article  ADS  CAS  Google Scholar 

  19. Brown, R. H. et al. Cassini's Visual and Infrared Mapping Spectrometer (VIMS): Observations during approach and orbit insertion. Astrophys. J. Lett. (in the press)

  20. Cruikshank, D. P. et al. Constraints on the composition of Trojan asteroid 624 Hektor. Icarus 153, 348–360 (2001)

    Article  ADS  CAS  Google Scholar 

  21. Clark, R. N. et al. Imaging spectroscopy: Earth and planetary remote sensing with the USGS Tetracorder and expert systems. J. Geophys. Res. 108, 5131, doi:10.1029/2002JE001847 (2003)

    Google Scholar 

Download references

Acknowledgements

This work was funded by the Cassini project. Authors from American institutions were funded by NASA; authors from European institutions were funded by ESA.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Roger N. Clark.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Clark, R., Brown, R., Jaumann, R. et al. Compositional maps of Saturn's moon Phoebe from imaging spectroscopy. Nature 435, 66–69 (2005). https://doi.org/10.1038/nature03558

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature03558

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing