Skip to main content

Thank you for visiting 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.

  • Letter
  • Published:

Convection in a volatile nitrogen-ice-rich layer drives Pluto’s geological vigour

A Corrigendum to this article was published on 06 July 2016


The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto’s vigorous geological activity1,2. Composed of molecular nitrogen, methane, and carbon monoxide ices3, but dominated by nitrogen ice, this layer is organized into cells or polygons, typically about 10 to 40 kilometres across, that resemble the surface manifestation of solid-state convection1,2. Here we report, on the basis of available rheological measurements4, that solid layers of nitrogen ice with a thickness in excess of about one kilometre should undergo convection for estimated present-day heat-flow conditions on Pluto. More importantly, we show numerically that convective overturn in a several-kilometre-thick layer of solid nitrogen can explain the great lateral width of the cells. The temperature dependence of nitrogen-ice viscosity implies that the ice layer convects in the so-called sluggish lid regime5, a unique convective mode not previously definitively observed in the Solar System. Average surface horizontal velocities of a few centimetres a year imply surface transport or renewal times of about 500,000 years, well under the ten-million-year upper-limit crater retention age for Sputnik Planum2. Similar convective surface renewal may also occur on other dwarf planets in the Kuiper belt, which may help to explain the high albedos shown by some of these bodies.

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

Access options

Buy this article

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

Figure 1: Image, topographic and map views of Sputnik Planum, Pluto.
Figure 2: High-resolution images of cellular terrain within SP.
Figure 3: Minimum thickness for convection in a layer of solid N2 ice on Pluto, as a function of basal temperature.
Figure 4: Example numerical model of N2 ice convection in SP.

Similar content being viewed by others


  1. Stern, S. A. et al. The Pluto system: initial results from its exploration by New Horizons. Science 350, aad1815 (2015)

    Article  ADS  CAS  Google Scholar 

  2. Moore, J. M. et al. The geology of Pluto and Charon through the eyes of New Horizons. Science 351, 1284–1293 (2016)

    Article  ADS  CAS  Google Scholar 

  3. Grundy, W. et al. Surface compositions across Pluto and Charon. Science 351, aad9189 (2016)

    Article  ADS  CAS  Google Scholar 

  4. Yamashita, Y., Kato, M. & Arakawa, M. Experimental study on the rheological properties of polycrystalline solid nitrogen and methane: implications for tectonic processes on Triton. Icarus 207, 972–977 (2010)

    Article  ADS  CAS  Google Scholar 

  5. Hammond, N. P. & Barr, A. C. Formation of Ganymede’s grooved terrain by convection-driven resurfacing. Icarus 227, 206–209 (2014)

    Article  ADS  Google Scholar 

  6. Schenk, P. M. et al. A large impact origin for Sputnik Planum and surrounding terrains, Pluto? AAS/Div. Planet. Sci. Meeting 47, abstr. 200.06 (2015)

    ADS  Google Scholar 

  7. Greenstreet, S., Gladman, B. & McKinnon, W. B. Impact and cratering rates onto Pluto. Icarus 258, 267–288 (2015)

    Article  ADS  Google Scholar 

  8. Moore, J. M. et al. Geology before Pluto: pre-encounter considerations. Icarus 246, 65–81 (2015)

    Article  ADS  Google Scholar 

  9. Stern, S. A., Porter, S. B. & Zangari, A. M. On the roles of escape erosion and the viscous relaxation of craters on Pluto. Icarus 250, 287–293 (2015)

    Article  ADS  CAS  Google Scholar 

  10. Eluszkiewicz, J. & Stevenson, D. J. Rheology of solid methane and nitrogen: application to Triton. Geophys. Res. Lett. 17, 1753–1756 (1990)

    Article  ADS  CAS  Google Scholar 

  11. Protopapa, S. et al. Methane to nitrogen mixing ratio across the surface of Pluto. Proc. Lunar Planet. Sci. Conf. 47, abstr. 2815 (2016)

    ADS  Google Scholar 

  12. Eluszkiewicz, J. On the microphysical state of the surface of Triton. J. Geophys. Res. 96, 19217–19229 (1991)

    Article  ADS  Google Scholar 

  13. Solomatov, V. S. Scaling of temperature- and stress-dependent viscosity convection. Phys. Fluids 7, 266–274 (1995)

    Article  ADS  CAS  Google Scholar 

  14. Stansberry, J. A. & Yelle, R. V. Emissivity and the fate of Pluto’s atmosphere. Icarus 141, 299–306 (1999)

    Article  ADS  CAS  Google Scholar 

  15. Scott, T. A. Solid and liquid nitrogen. Phys. Rep. (Phys. Lett. C) 27, 89–157 (1976)

    ADS  Google Scholar 

  16. McKinnon, W. B., Simonelli, D. & Schubert, G. in Pluto and Charon (eds Stern, S. A. & Tholen, D. J. ) 259–343 (Univ. Arizona Press, 1997)

  17. Robuchon, G. & Nimmo, F. Thermal evolution of Pluto and implications for surface tectonics and a subsurface ocean. Icarus 216, 426–439 (2011)

    Article  ADS  Google Scholar 

  18. Lodders, K. Solar System abundances and condensation temperatures of the elements. Astrophys. J. 591, 1220–1247 (2003)

    Article  ADS  CAS  Google Scholar 

  19. McKinnon, W. B. et al. The Pluto-Charon system revealed: geophysics, activity, and origins. Lunar Planet. Sci. Conf. 47, abstr. 1995 (2016)

    ADS  Google Scholar 

  20. Robuchon, G., Nimmo, F., Roberts, J. & Kirchoff, M. Impact basin relaxation at Iapetus. Icarus 214, 82–90 (2011)

    Article  ADS  Google Scholar 

  21. Estève, D. & Sullivan, N. S. NMR study of self-diffusion in solid N2 . Solid State Commun. 39, 969–971 (1981)

    Article  ADS  Google Scholar 

  22. Moresi, L.-N. & Solomatov, V. S. Numerical investigation of 2D convection with extremely large viscosity variations. Phys. Fluids 7, 2154–2162 (1995)

    Article  ADS  Google Scholar 

  23. Bland, M. T. & McKinnon, W. B. Forming Ganymede’s grooves at smaller strain: toward a self-consistent local and global strain history for Ganymede. Icarus 245, 247–262 (2015)

    Article  ADS  Google Scholar 

  24. Singer, K. N. & Stern, S. A. On the provenance of Pluto’s nitrogen (N2). Astrophys. J. 808, L50 (2015)

    Article  ADS  Google Scholar 

  25. Gladstone, G. R. et al. The atmosphere of Pluto as observed by New Horizons. Science 351, aad8866 (2016)

  26. Brown, M. E. in The Solar System Beyond Neptune (eds Barucci, M. A., Boehnhardt, H., Cruikshank, D. & Morbidelli, A. ) 335–344 (Univ. Arizona Press, 2008)

  27. Schenk, P. M., Wilson, R. R. & Davies, A. G. Shield volcano topography and the rheology of lava flows on Io. Icarus 169, 98–110 (2004)

    Article  ADS  CAS  Google Scholar 

  28. Schenk, P. M. Thickness constraints on the icy shells of the Galilean satellites from a comparison of crater shapes. Nature 417, 419–421 (2002)

    Article  ADS  CAS  Google Scholar 

  29. Frost, H. J. & Ashby, M. F. Deformation-Mechanism Maps: The Plasticity and Creep of Metals and Ceramics (Pergamon, 1982)

  30. Solomatov, V. S. & Moresi, L.-N. Three regimes of mantle convection with non-Newtonian viscosity and stagnant lid convection on the terrestrial planets. Geophys. Res. Lett. 24, 1907–1910 (1997)

    Article  ADS  Google Scholar 

  31. Barr, A. C. & McKinnon, W. B. Can Enceladus’ ice shell convect? Geophys. Res. Lett. 34, L09202 (2007)

    Article  ADS  Google Scholar 

  32. Stengel, K. C., Oliver, D. S. & Booker, J. R. Onset of convection in a variable viscosity fluid. J. Fluid Mech. 120, 411–431 (1982)

    Article  ADS  CAS  Google Scholar 

  33. Solomatov, V. S. & Barr, A. C. Onset of convection in fluids with strongly temperature-dependent, power-law viscosity: 2. Dependence on the initial perturbation. Phys. Earth Planet. Inter. 165, 1–13 (2007)

    Article  ADS  CAS  Google Scholar 

  34. Schubert, G., Turcotte, D. L. & Olson, P. Mantle Convection in the Earth and Planets (Cambridge Univ. Press, 2001)

  35. Goldsby, D. L. & Kohlstedt, D. L. Superplastic deformation of ice: experimental observations. J. Geophys. Res. 106, 11017–11030 (2001)

    Article  ADS  Google Scholar 

  36. Barr, A. C. & McKinnon, W. B. Convection in ice I shells and mantles with self-consistent grain size. J. Geophys. Res. 112, E02012 (2007)

    Article  ADS  Google Scholar 

  37. Cruikshank, D. P. et al. in Pluto and Charon (eds Stern, S. A. & Tholen, D. J. ) 221–267 (Univ. Arizona Press, 1997)

  38. Durham, W. B., Prieto-Ballesteros, O., Goldsby, D. L. & Kargel, J. S. Rheological and thermal properties of icy materials. Space Sci. Rev. 153, 273–298 (2010)

    Article  ADS  CAS  Google Scholar 

  39. Karato, S. & Wu, P. Rheology of the upper mantle: a synthesis. Science 260, 771–778 (1993)

    Article  ADS  CAS  Google Scholar 

  40. Elbeshausen, D., Wünnemann, K. & Collins, G. S. The transition from circular to elliptical impact craters. J. Geophys. Res. 118, 2295–2309 (2013)

    Article  Google Scholar 

Download references


New Horizons was built and operated by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, USA, for NASA. We thank the many engineers who have contributed to the success of the New Horizons mission, and NASA’s Deep Space Network (DSN) for a decade of support of New Horizons. This work was supported by NASA’s New Horizons project.

Author information

Authors and Affiliations




W.B.M. led the study and wrote the paper, with substantial input from F.N.; T.W. and J.H.R. performed the CitCom finite element convection calculations; P.M.S. developed the software to create stereographic and photoclinometric digital elevation models (DEMs) using New Horizons LORRI and MVIC images, and created the preliminary DEM for SP; O.L.W. mapped the SP region using New Horizons images in ArcGIS; J.M.M., J.R.S., A.D.H, O.M.U. and S.A.S. contributed to the understanding of the multiple roles N2 ice plays in the geology of SP and its environs. S.A.S., H.A.W., C.B.O., L.A.Y. and K.E.S. are the lead scientists of the New Horizons project. The entire Geology, Geophysics, and Imaging Theme Team (listed) contributed to the success of the Pluto encounter.

Corresponding author

Correspondence to William B. McKinnon.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

All spacecraft data and higher-order products presented in this Letter will be delivered to NASA’s Planetary Data System ( in a series of stages in 2016 and 2017 because of the time required to fully downlink and calibrate the data set.

Related audio

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

McKinnon, W., Nimmo, F., Wong, T. et al. Convection in a volatile nitrogen-ice-rich layer drives Pluto’s geological vigour. Nature 534, 82–85 (2016).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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.


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