Letter | Published:

Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia

Nature volume 540, pages 9093 (01 December 2016) | Download Citation

Abstract

Pluto is an astoundingly diverse, geologically dynamic world. The dominant feature is Sputnik Planitia—a tear-drop-shaped topographic depression approximately 1,000 kilometres in diameter possibly representing an ancient impact basin1,2. The interior of Sputnik Planitia is characterized by a smooth, craterless plain three to four kilometres beneath the surrounding rugged uplands, and represents the surface of a massive unit of actively convecting volatile ices (N2, CH4 and CO) several kilometres thick1,2,3,4,5. This large feature is very near the Pluto–Charon tidal axis. Here we report that the location of Sputnik Planitia is the natural consequence of the sequestration of volatile ices within the basin and the resulting reorientation (true polar wander) of Pluto. Loading of volatile ices within a basin the size of Sputnik Planitia can substantially alter Pluto’s inertia tensor, resulting in a reorientation of the dwarf planet of around 60 degrees with respect to the rotational and tidal axes. The combination of this reorientation, loading and global expansion due to the freezing of a possible subsurface ocean generates stresses within the planet’s lithosphere, resulting in a global network of extensional faults that closely replicate the observed fault networks on Pluto. Sputnik Planitia probably formed northwest of its present location, and was loaded with volatiles over million-year timescales as a result of volatile transport cycles on Pluto6,7. Pluto’s past, present and future orientation is controlled by feedbacks between volatile sublimation and condensation, changing insolation conditions and Pluto’s interior structure.

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Acknowledgements

We thank the New Horizons science team for their many years of work that resulted in the successful flyby of Pluto, and for promptly releasing the public data and published work1,2,3,4,13,16 that enabled this research. We note that all names of features on Pluto are informal. J.T.K. acknowledges support from the University of Arizona Theoretical Astrophysics Program and NASA Solar System Workings.

Author information

Affiliations

  1. Lunar and Planetary Laboratory, Department of Planetary Science, University of Arizona, Tucson, Arizona 85721, USA

    • James T. Keane
    •  & Isamu Matsuyama
  2. Creative Research Institution, Hokkaido University, Sapporo, Japan

    • Shunichi Kamata
  3. Purdue University, Department of Earth, Atmospheric, and Planetary Sciences, West Lafayette, Indiana 47907, USA

    • Jordan K. Steckloff
  4. Planetary Science Institute, Tucson, Arizona 85719, USA

    • Jordan K. Steckloff

Authors

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Contributions

J.T.K. identified the link between Sputnik Planitia and the tidal axis, performed true polar wander analyses, mapping and analysis of tectonic features, proposed connection between polar wander and secular volatile transport, was the primary author of the text and created all figures. I.M. performed analyses of Pluto’s shape and gravity field and performed tectonics calculations. S.K. provided Love numbers for Pluto. J.K.S. provided estimates of volatile deposition timescales for Sputnik Planitia and provided input on volatile transport.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to James T. Keane.

Extended data

Supplementary information

Videos

  1. 1.

    Reorientation and faulting of Pluto due to the progressive loading of Sputnik Planum

    Orthographic spherical projection of Pluto as it reorients in response to the transfer of volatiles from two polar caps into Sputnik Planum (as in Fig. 3d-i), as viewed from reference frame fixed to Pluto’s instantaneous principal axes of inertia. Color corresponds to ice thickness in one of the three possible reservoirs: the polar caps, Sputnik Planum, or the equatorial band (which is always ice-free in this simple model). The total volatile reservoir is equivalent to a global layer 200 meters thick. Observed tectonic patterns are in white, and predicted tectonic patterns at every time-step are shown colored by their azimuth (as in Fig. 2).

  2. 2.

    Reorientation and faulting of Pluto due to the progressive loading of Sputnik Planum—Western Faults

    Orthographic spherical projection of Pluto as it reorients in response to the transfer of volatiles from two polar caps into Sputnik Planum (as in Fig. 3d-i), as viewed from reference frame fixed above the faults west of Sputnik Planum. All symbols and colors are the same as in Supplementary Video 1. Snapshots of this video are shown in Extended Data Figure 8.

  3. 3.

    Reorientation and faulting of Pluto due to the progressive loading of Sputnik Planum—Eastern Faults

    Orthographic spherical projection of Pluto as it reorients in response to the transfer of volatiles from two polar caps into Sputnik Planum (as in Fig. 3d-i), as viewed from reference frame fixed above the faults east of Sputnik Planum. All symbols and colors are the same as in Supplementary Video 1. Snapshots of this video are shown in Extended Data Figure 8.

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DOI

https://doi.org/10.1038/nature20120

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