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Formation of metre-scale bladed roughness on Europa’s surface by ablation of ice


On Earth, the sublimation of massive ice deposits at equatorial latitudes under cold and dry conditions in the absence of any liquid melt leads to the formation of spiked and bladed textures eroded into the surface of the ice. These sublimation-sculpted blades are known as penitentes. For this process to take place on another planet, the ice must be sufficiently volatile to sublimate under surface conditions and diffusive processes that act to smooth the topography must operate more slowly. Here we calculate sublimation rates of water ice across the surface of Jupiter’s moon Europa. We find that surface sublimation rates exceed those of erosion by space weathering processes in Europa’s equatorial belt (latitudes below 23°), and that conditions would favour penitente growth. We estimate that penitentes on Europa could reach 15 m in depth with a spacing of 7.5 m near the equator, on average, if they were to have developed across the interval permitted by Europa’s mean surface age. Although available images of Europa have insufficient resolution to detect surface roughness at the multi-metre scale, radar and thermal data are consistent with our interpretation. We suggest that penitentes could pose a hazard to a future lander on Europa.

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The data that support the findings of this study are available on the NASA Planetary Data System (PDS) (

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  1. 1.

    Greeley, R. et al. in Jupiter: The Planet, Satellites and Magnetosphere (eds Bagenal, F. & Dowling, T. E.) 329–362 (Cambridge University Press, Cambridge, 2004).

  2. 2.

    Luchitta, B. K. & Soderblom, L. A. in Satellites of Jupiter (ed. Morrison, D.) 521–555 (University of Arizona Press, Tucson, 1982).

  3. 3.

    Schenk, P. M., Matsuyama, I. & Nimmo, F. True polar wander on Europa from global-scale small-circle depressions. Nature 453, 368–371 (2008).

  4. 4.

    Spencer, J. R., Tamppari, L. K., Martin, T. Z. & Travis, L. D. Temperatures on Europa from Galileo photopolarimeter-radiometer: nighttime thermal anomalies. Science 284, 1514–1516 (1999).

  5. 5.

    Moore, J. M. et al. in Europa (eds Pappalardo, R. T. et al.) 329–349 (University of Arizona Press, Tucson, 2009).

  6. 6.

    Moore, J. M. et al. Mass movement and landform degradation on the icy Galilean satellites: results of the Galileo Nominal Mission. Icarus 140, 294–312 (1999).

  7. 7.

    Buratti, B. J. & Golombek, M. P. Geologic implications of spectrophotometric measurements of Europa. Icarus 75, 437–449 (1988).

  8. 8.

    Bierhaus, E. B., Zahnle, K. & Chapman, C. R. in Europa (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K. K.) 161–180 (University of Arizona Press, Tucson, 2009).

  9. 9.

    Johnson, R. E. et al. in Europa (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K. K.) 507–527 (University of Arizona Press, Tucson, 2009).

  10. 10.

    Domingue, D. L., Hapke, B. W., Lockwood, G. W. & Thompson, D. T. Europaʼs phase curve: implications for surface structure. Icarus 90, 30–42 (1991).

  11. 11.

    Betterton, M. Theory of structure formation in snowfields motivated by penitentes, suncups, and dirt cones. Phys. Rev. E 63, 056129 (2001).

  12. 12.

    Lliboutry, L. The origin of penitents. J. Glaciol. 2, 331–338 (1954).

  13. 13.

    Corripio, J. G. Modelling the Energy Balance of High Altitude Glacierised Basins in the Central Andes (Univ. Edinburgh, 2002).

  14. 14.

    Cathles, L. M. Radiative Energy Transport on the Surface of an Ice Sheet (Univ. Chicago, 2011).

  15. 15.

    Rhodes, J. J., Armstrong, R. L. & Warren, S. G. Mode of formation of ‘ablation hollows’ controlled by dirt content of snow. J. Glaciol. 33, 135–139 (1987).

  16. 16.

    Claudin, P., Jarry, H., Vignoles, G., Plapp, M. & Andreotti, B. Physical processes causing the formation of penitentes. Phys. Rev. E 92, 033015 (2015).

  17. 17.

    Ostro, S. J. et al. Europa, Ganymede, and Callisto: new radar results from Arecibo and Goldstone. J. Geophys. Res. 97, 18227–18244 (1992).

  18. 18.

    Ostro, S. J. in Satellites of Jupiter (ed. Morrison, D.) 213–236 (Univ. Arizona Press, Tucson, 1982).

  19. 19.

    Moore, J. M. et al. Bladed terrain on Pluto: possible origins and evolution. Icarus 300, 129–144 (2018).

  20. 20.

    Saur, J., Strobel, D. F. & Neubauer, F. M. Interaction of the Jovian magnetosphere with Europa: constraints on the neutral atmosphere. J. Geophys. Res. 103, 19947–19962 (1998).

  21. 21.

    Moore, J. M. et al. Sublimation as a landform-shaping process on Pluto. Icarus 287, 320–333 (2017).

  22. 22.

    Bergeron, V., Berger, C. & Betterton, M. Controlled irradiative formation of penitentes. Phys. Rev. Lett. 96, 098502 (2006).

  23. 23.

    Cathles, L. M., Abbot, D. S. & MacAyeal, D. R. Intra-surface radiative transfer limits the geographic extent of snow penitents on horizontal snowfields. J. Glaciol. 60, 147–154 (2014).

  24. 24.

    Lhermitte, S., Abermann, J. & Kinnard, C. Albedo over rough snow and ice surfaces. Cryosphere 8, 1069–1086 (2014).

  25. 25.

    Ward, W. R. & Canup, R. M. The obliquity of Jupiter. Astrophys. J. 640, L91–L94 (2006).

  26. 26.

    Bierhaus, E. B. et al. Pwyll secondaries and other small craters on Europa. Icarus 153, 264–276 (2001).

  27. 27.

    Paranicas, C., Cooper, J. F., Garrett, H. B., Johnson, R. E. & Sturner, S. J. in Europa (eds Pappalardo, R. T., McKinnon, W. B. & Khurana, K. K.) 529–544 (Univ. Arizona Press, Tuscon, 2009).

  28. 28.

    Morrison, D. & Morrison, N. in Planetary Satellites (ed. Burns, J.) 363–378 (Univ. Arizona Press, Tucson, 1977).

  29. 29.

    Grundy, W. M. et al. New horizons mapping of Europa and Ganymede. Science 318, 234–237 (2007).

  30. 30.

    Schenk, P. M. Slope characteristics of Europa: constraints for landers and radar sounding. Geophys. Res. Lett. 36, L15204 (2009).

  31. 31.

    Rathbun, J. A., Rodriguez, N. J. & Spencer, J. R. Galileo PPR observations of Europa: hotspot detection limits and surface thermal properties. Icarus 210, 763–769 (2010).

  32. 32.

    Goldstein, R. M. & Green, R. R. Ganymede: radar surface characteristics. Science 207, 179–180 (1980).

  33. 33.

    Ostro, S. J. & Pettengill, G. H. Icy craters on the galilean satellites? Icarus 34, 268–279 (1978).

  34. 34.

    Campbell, B. A. High circular polarization ratios in radar scattering from geologic targets. J. Geophys. Res. 117, E06008 (2012).

  35. 35.

    Lebofsky, L. A. Stability of frosts in the solar system. Icarus 25, 205–217 (1975).

  36. 36.

    Spencer, J. R. The Surfaces of Europa, Ganymede, and Callisto: An Investigation Using Voyager IRIS Thermal Infrared Spectra (Univ. Arizona, 1987).

  37. 37.

    Fray, N. & Schmitt, B. Sublimation of ices of astrophysical interest: a bibliographic review. Planet. Space. Sci. 57, 2053–2080 (2009).

  38. 38.

    Feistel, R. & Wagner, W. Sublimation pressure and sublimation enthalpy of H2O ice Ih between 0 and 273.16 K. Geochim. Cosmochim. Acta 71, 36–45 (2007).

  39. 39.

    White, B. E., Hessinger, J. & Pohl, R. O. Annealing and sublimation of noble gas and water ice films. J. Low Temp. Phys. 111, 233–246 (1998).

  40. 40.

    Mauersberger, K. & Krankowsky, D. Vapor pressure above ice at temperatures below 170 K. Geophys. Res. Lett. 30, 1121 (2003).

  41. 41.

    Bender, C. M. & Orszag, S. A. Advanced Mathematical Methods for Scientists and Engineers (McGraw-Hill, New York, 1978).

  42. 42.

    Shematovich, V. I., Johnson, R. E., Cooper, J. F. & Wong, M. C. Surface bound atmosphere of Europa. Icarus 173, 480–498 (2005).

  43. 43.

    Smyth, W. H. & Marconi, M. L. Europa’s atmosphere, gas tori, and magnetospheric implications. Icarus 181, 510–526 (2006).

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We thank D. Blankenship, K. Mitchell, F. Nimmo and G. Tucker, and especially J. Spencer for discussions that shaped the form of this paper. Funding was from the Europa Pre-Project Mission Concept Study via the Jet Propulsion Laboratory, California Institute of Technology. We are grateful to P. Engebretson for contribution to figure production. We thank C. Chavez for her help with manuscript preparation.

Author information

D.E.J.H. compiled data, performed and interpreted numerical analyses, and wrote the bulk of the paper. J.M.M. conceived and designed the study and organized the revision of the manuscript. A.D.H. was involved in the study, design, interpretation, and revision. Both J.M.M. and A.D.H. performed preliminary analyses. O.M.U. significantly revised the numerical analyses found in the Methods section. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing interests.

Correspondence to Daniel E. J. Hobley.

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Fig. 1: Terrestrial penitentes from the southern end of the Chajnantor plain, Chile.
Fig. 2: Modelled variation in rates of surface sublimation, and equivalent total depth of ice removal, with Europan latitude.
Fig. 3: Remote sensing evidence consistent with an equatorial band of penitentes on Europa.