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Micro cold traps on the Moon


Water ice is thought to be trapped in large permanently shadowed regions in the Moon’s polar regions, due to their extremely low temperatures. Here, we show that many unmapped cold traps exist on small spatial scales, substantially augmenting the areas where ice may accumulate. Using theoretical models and data from the Lunar Reconnaissance Orbiter, we estimate the contribution of shadows on scales from 1 km to 1 cm, the smallest distance over which we find cold-trapping to be effective for water ice. Approximately 10–20% of the permanent cold-trap area for water is found to be contained in these micro cold traps, which are the most numerous cold traps on the Moon. Consideration of all spatial scales therefore substantially increases the number of cold traps over previous estimates, for a total area of ~40,000 km2, about 60% of which is in the south. A majority of cold traps for water ice is found at latitudes > 80° because permanent shadows equatorward of 80° are typically too warm to support ice accumulation. Our results suggest that water trapped at the lunar poles may be more widely distributed and accessible as a resource for future missions than previously thought.

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Fig. 1: Images reveal shadows on a range of spatial scales.
Fig. 2: Modelled surface temperatures at 85° latitude for similar surfaces with two different values of σs.
Fig. 3: Fraction of total surface area at each latitude remaining perennially below 110 K, the adopted sublimation temperature for water ice.
Fig. 4: Permanently shadowed and cold-trapping areas as a function of size in the northern and southern hemispheres.

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Data availability

All data used in this study are publicly available. The Diviner and LROC data can be accessed through the NASA Planetary Data System: The higher-level data products generated in this study are available from the authors and on GitHub:

Code availability

All code generated by this study is available from the authors and/or on GitHub: and


  1. Urey, H. C. The Planets, Their Origin and Development (Yale Univ. Press, 1952).

  2. Watson, K., Murray, B. C. & Brown, H. On the possible presence of ice on the Moon. J. Geophys. Res. 66, 1598–1600 (1961).

    Article  ADS  Google Scholar 

  3. Vasavada, A. R., Paige, D. A. & Wood, S. E. Near-surface temperatures on Mercury and the Moon and the stability of polar ice deposits. Icarus 141, 179–193 (1999).

    Article  ADS  Google Scholar 

  4. Harmon, J. K. & Slade, M. A. Radar mapping of Mercury: full-disk images and polar anomalies. Science 258, 640–643 (1992).

    Article  ADS  Google Scholar 

  5. Harmon, J. K., Slade, M. A. & Rice, M. S. Radar imagery of Mercury’s putative polar ice: 1999–2005 Arecibo results. Icarus 211, 37–50 (2011).

    Article  ADS  Google Scholar 

  6. Platz, T. et al. Surface water-ice deposits in Ceres’s northern permanent shadows. Nat. Astron. 1, 0007 (2017).

  7. Neumann, G. A. et al. Bright and dark polar deposits on Mercury: evidence for surface volatiles. Science 339, 296–300 (2013).

    Article  ADS  Google Scholar 

  8. Paige, D. A. et al. Thermal stability of volatiles in the north polar region of Mercury. Science 339, 300–303 (2013).

    Article  ADS  Google Scholar 

  9. Ermakov, A. I. et al. Ceres’ obliquity history and its implications for permanently shadowed regions. Geophys. Res. Lett. 44, 2652–2661 (2017).

    Article  ADS  Google Scholar 

  10. Margot, J. L., Campbell, D. B., Jurgens, R. F. & Slade, M. A. Topography of the lunar poles from radar interferometry: a survey of cold trap locations. Science 284, 1658–1660 (1999).

    Article  ADS  Google Scholar 

  11. Feldman, W. C. et al. Global distribution of neutrons from Mars: results from Mars Odyssey. Science 297, 75–78 (2002).

    Article  ADS  Google Scholar 

  12. Colaprete, A. et al. Detection of water in the LCROSS ejecta plume. Science 330, 463–468 (2010).

    Article  ADS  Google Scholar 

  13. Watson, K., Murray, B. C. & Brown, H. The behavior of volatiles on the lunar surface. J. Geophys. Res. 66, 3033–3045 (1961).

    Article  ADS  Google Scholar 

  14. Arnold, J. R. Ice in the lunar polar regions. J. Geophys. Res. 84, 5659 (1979).

    Article  ADS  Google Scholar 

  15. Chin, G. et al. Lunar Reconnaissance Orbiter overview: the instrument suite and mission. Space Sci. Rev. 129, 391–419 (2007).

    Article  ADS  Google Scholar 

  16. Elvis, M., Milligan, T. & Krolikowski, A. The peaks of eternal light: a near-term property issue on the Moon. Space Policy 38, 30–38 (2016).

    Article  ADS  Google Scholar 

  17. NASA The Artemis Accords (accessed 25 June 2020).

  18. Paige, D. A. et al. Diviner Lunar Radiometer observations of cold traps in the Moon’s south polar region. Science 330, 479–482 (2010).

    Article  ADS  Google Scholar 

  19. Mazarico, E., Neumann, G. A., Smith, D. E., Zuber, M. T. & Torrence, M. H. Illumination conditions of the lunar polar regions using LOLA topography. Icarus 211, 1066–1081 (2011).

    Article  ADS  Google Scholar 

  20. Hayne, P. O. et al. Evidence for exposed water ice in the Moon’s south polar regions from Lunar Reconnaissance Orbiter ultraviolet albedo and temperature measurements. Icarus 255, 58–69 (2015).

    Article  ADS  Google Scholar 

  21. Buhl, D., Welch, W. J. & Rea, D. G. Reradiation and thermal emission from illuminated craters on the lunar surface. J. Geophys. Res. 73, 5281–5295 (1968).

    Article  ADS  Google Scholar 

  22. Bandfield, J. L., Hayne, P. O., Williams, J.-P., Greenhagen, B. T. & Paige, D. A. Lunar surface roughness derived from LRO Diviner Radiometer observations. Icarus 248, 357–372 (2015).

    Article  ADS  Google Scholar 

  23. Rubanenko, L. & Aharonson, O. Stability of ice on the Moon with rough topography. Icarus 296, 99–109 (2017).

    Article  ADS  Google Scholar 

  24. Robinson, M. et al. Lunar Reconnaissance Orbiter Camera (LROC) instrument overview. Space Sci. Rev. 150, 81–124 (2010).

    Article  ADS  Google Scholar 

  25. Aharonson, O. & Schorghofer, N. Subsurface ice on Mars with rough topography. J. Geophys. Res. 111, E11007 (2006).

  26. Hayne, P. O. & Aharonson, O. Thermal stability of ice on Ceres with rough topography. J. Geophys. Res. 120, 1567–1584 (2015).

    Article  Google Scholar 

  27. Bussey, D. B. J. et al. Permanent shadow in simple craters near the lunar poles. Geophys. Res. Lett. 30, 1278 (2003).

    ADS  Google Scholar 

  28. Smith, B. G. Lunar surface roughness: shadowing and thermal emission. J. Geophys. Res. 72, 4059–4067 (1967).

    Article  ADS  Google Scholar 

  29. Rosenburg, M. et al. Global surface slopes and roughness of the Moon from the Lunar Orbiter Laser Altimeter. J. Geophys. Res. 116, E02001 (2011).

  30. Hayne, P. O. et al. Global regolith thermophysical properties of the moon from the Diviner lunar radiometer experiment. J. Geophys. Res. 122, 2371–2400 (2017).

    Article  Google Scholar 

  31. Ingersoll, A. P., Svitek, T. & Murray, B. C. Stability of polar frosts in spherical bowl-shaped craters on the Moon, Mercury, and Mars. Icarus 100, 40–47 (1992).

    Article  ADS  Google Scholar 

  32. Mahanti, P. et al. Inflight calibration of the Lunar Reconnaissance Orbiter Camera Wide Angle Camera. Space Sci. Rev. 200, 393–430 (2016).

    Article  ADS  Google Scholar 

  33. Helfenstein, P. & Shepard, M. K. Submillimeter-scale topography of the lunar regolith. Icarus 141, 107–131 (1999).

    Article  ADS  Google Scholar 

  34. Williams, J.-P. et al. Seasonal polar temperatures on the Moon. J. Geophys. Res. 124, 2505–2521 (2019).

    Article  Google Scholar 

  35. Rubanenko, L., Venkatraman, J. & Paige, D. A. Thick ice deposits in shallow simple craters on the Moon and Mercury. Nat. Geosci. 12, 597–601 (2019).

    Article  ADS  Google Scholar 

  36. Poston, M. J. et al. Temperature programmed desorption studies of water interactions with Apollo lunar samples 12001 and 72501. Icarus 255, 24–29 (2015).

    Article  ADS  Google Scholar 

  37. Farrell, W. et al. The young age of the LAMP-observed frost in lunar polar cold traps. Geophys. Res. Lett. 46, 8680–8688 (2019).

    Article  ADS  Google Scholar 

  38. Moores, J. E. Lunar water migration in the interval between large impacts: heterogeneous delivery to permanently shadowed regions, fractionation, and diffusive barriers. J. Geophys. Res. 121, 46–60 (2016).

    Article  Google Scholar 

  39. Pike, R. J. in Impact and Explosion Cratering: Planetary and Terrestrial Implications Vol. 1 (eds Roddy, D. J. et al.) 489–509 (Pergamon, 1977).

  40. Aharonson, O., Schorghofer, N. & Hayne, P. O. Size and solar incidence distribution of shadows on the Moon. In Proc. Lunar and Planetary Science Conference Vol. XLVIII, 2245 (Lunar and Planetary Institute, 2017).

  41. Pike, R. J. Depth/diameter relations of fresh lunar craters: revision from spacecraft data. Geophys. Res. Lett. 1, 291–294 (1974).

    Article  ADS  Google Scholar 

  42. Schörghofer, N. Planetary-Code-Collection: thermal and ice evolution models for planetary surfaces v1.1.4 (2017).

  43. Longuet-Higgins, M. S. Statistical properties of an isotropic random surface. Philos. Trans. R. Soc. A 250, 157 (1957).

    ADS  MathSciNet  MATH  Google Scholar 

  44. Janna, W. S. Engineering Heat Transfer 2nd edn (CRC Press, 1999).

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This study was supported by the Lunar Reconnaissance Orbiter project and NASA’s Solar System Exploration Research Virtual Institute. We thank E. Mazarico for valuable discussions and data on PSR area derived from LOLA elevation data and illumination models, and P. Mahanti for crater depth/diameter ratio data. We also thank P. G. Lucey for insightful criticism that improved this work. O.A. wishes to thank the Helen Kimmel Center for Planetary Science, the Minerva Center for Life Under Extreme Planetary Conditions and the I-CORE Program of the PBC and ISF (centre no. 1829/12). N.S. was in part supported by the NASA Solar System Exploration Research Virtual Institute Cooperative Agreement (NNH16ZDA001N) (TREX).

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Authors and Affiliations



P.O.H. initiated the study, developed the approach and general methodology, analysed the Diviner data and performed the model fitting. O.A. compiled the shadow fractions from images, computed the lateral heat conduction limitation and helped to construct the overall description of cold-trap scale dependence. N.S. derived the equations for shadows in a bowl-shaped crater and carried out the numerical energy balance calculations. All authors contributed to the writing of the manuscript.

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Correspondence to P. O. Hayne.

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The authors declare no competing interests.

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Peer review information Nature Astronomy thanks Timothy McClanahan and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Hayne, P.O., Aharonson, O. & Schörghofer, N. Micro cold traps on the Moon. Nat Astron 5, 169–175 (2021).

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