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.

  • Perspective
  • Published:

Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water

Abstract

Recent liquid water flow on Mars has been proposed based on geomorphological features, such as gullies. Recurring slope lineae — seasonal flows that are darker than their surroundings — are candidate locations for seeping liquid water on Mars today, but their formation mechanism remains unclear. Topographical analysis shows that the terminal slopes of recurring slope lineae match the stopping angle for granular flows of cohesionless sand in active Martian aeolian dunes. In Eos Chasma, linea lengths vary widely and are longer where there are more extensive angle-of-repose slopes, inconsistent with models for water sources. These observations suggest that recurring slope lineae are granular flows. The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, alleviating planetary protection concerns about habitable environments.

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

Fig. 1: RSL slopes and profiles.
Fig. 2: Merger of a climbing dune and slope lineae.

NASA/JPL/University of Arizona.

Fig. 3: RSL fans transitioning downhill into aeolian bedforms.

NASA/JPL/University of Arizona.

Similar content being viewed by others

References

  1. Gough, R. V., Chevrier, V. F., Baustian, K. J., Wise, M. E. & Tolbert, M. A. Laboratory studies of perchlorate phase transitions: support for metastable aqueous perchlorate solutions on Mars. Earth Planet. Sci. Lett. 312, 371–377 (2011).

    Article  Google Scholar 

  2. Gough, R. V., Chevrier, V. F. & Tolbert, M. A. Formation of liquid water at low temperatures via the deliquescence of calcium chloride: implications for Antarctica and Mars. Planet. Space Sci. 131, 79–87 (2016).

    Article  Google Scholar 

  3. Martin-Torres, F. J. et al. Transient liquid water and water activity at Gale crater on Mars. Nat. Geosci. 8, 357–361 (2015).

    Article  Google Scholar 

  4. Nuding, D. L. et al. Deliquescence and efflorescence of calcium perchlorate: an investigation of stable aqueous solutions relevant to Mars. Icarus 243, 420–428 (2014).

    Article  Google Scholar 

  5. Malin, M. C. & Edgett, K. S. Evidence for recent groundwater seepage and surface runoff on Mars. Science 288, 2330–2335 (2000).

    Article  Google Scholar 

  6. McEwen, A. S. et al. Seasonal flows on warm Martian slopes. Science 333, 740–743 (2011).

    Article  Google Scholar 

  7. Dundas, C. M., Diniega, S. & McEwen, A. S. Long-term monitoring of Martian gully formation and evolution with MRO/HiRISE. Icarus 251, 244–263 (2015).

    Article  Google Scholar 

  8. McEwen, A. S. et al. Recurring slope lineae in equatorial regions of Mars. Nat. Geosci. 7, 53–58 (2014).

    Article  Google Scholar 

  9. Stillman, D. E., Michaels, T. I., Grimm, R. E. & Harrison, K. P. New observations of Martian southern mid-latitude recurring slope lineae (RSL) imply formation by freshwater subsurface flows. Icarus 233, 328–341 (2014).

    Article  Google Scholar 

  10. Stillman, D. E., Michaels, T. I., Grimm, R. E. & Hanley, J. Observations and modeling of northern mid-latitude recurring slope lineae (RSL) suggest recharge by a present-day Martian briny aquifer. Icarus 265, 125–138 (2016).

    Article  Google Scholar 

  11. Chojnacki, M. et al. Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars. J. Geophys. Res. https://doi.org/10.1002/2015JE004991 (2016).

  12. Stillman, D. E., Michaels, T. I. & Grimm, R. E. Characteristics of the numerous and widespread recurring slope lineae (RSL) in Valles Marineris, Mars. Icarus 285, 195–210 (2017).

    Article  Google Scholar 

  13. Chevrier, V. F. & Rivera-Valentin, E. G. Formation of recurring slope lineae by liquid brines on present-day Mars. Geophys. Res. Lett. 39, L21202 (2012).

    Article  Google Scholar 

  14. Levy, J. Hydrological characteristics of recurrent slope lineae on Mars: evidence for liquid flow through regolith and comparisons with Antarctic terrestrial analogs. Icarus 219, 1–4 (2012).

    Article  Google Scholar 

  15. Grimm, R. E., Harrison, K. P. & Stillman, D. E. Water budgets of Martian recurring slope lineae. Icarus 233, 316–327 (2014).

    Article  Google Scholar 

  16. Massé, M. et al. Spectroscopy and detectability of liquid brines on Mars. Planet. Space Sci. 92, 136–149 (2014).

    Article  Google Scholar 

  17. Schmidt, F., Andrieu, F., Costard, F., Kocifaj, M. & Meresescu, A. G. Formation of recurring slope lineae on Mars by rarefied gas-triggered granular flows. Nat. Geosci. 10, 270–274 (2017).

    Article  Google Scholar 

  18. Edwards, C. S. & Piqueux, S. The water content of recurring slope lineae on Mars. Geophys. Res. Lett. https://doi.org/10.1002/2016GL070179 (2016).

  19. Ojha, L. et al. Spectral evidence for hydrated salts in recurring slope lineae on Mars. Nat. Geosci. 8, 829–833 (2015).

    Article  Google Scholar 

  20. Mitchell, J. L. & Christensen, P. R. Recurring slope lineae and chlorides on the surface of Mars. J. Geophys. Res. Planets 121, 1411–1428 (2016).

    Article  Google Scholar 

  21. Martinez, G. M. & Renno, N. O. Water and brines on Mars: current evidence and implications for MSL. Space Sci. Rev. 175, 29–51 (2013).

    Article  Google Scholar 

  22. Ingersoll, A. P. Mars: occurrence of liquid water. Science 168, 972–973 (1970).

    Google Scholar 

  23. Atwood-Stone, C. & McEwen, A. S. Avalanche slope angles in low-gravity environments from active Martian sand dunes. Geophys. Res. Lett. 40, 2929–2934 (2013).

    Article  Google Scholar 

  24. Ojha, L. et al. HiRISE observations of recurring slope lineae (RSL) during southern summer on Mars. Icarus 231, 365–376 (2014).

    Article  Google Scholar 

  25. Conway, S. J., Balme, M. R., Kreslavsky, M. A., Murray, J. B. & Towner, M. C. The comparison of topographic long profiles of gullies on Earth to gullies on Mars: a signal of water on Mars. Icarus 253, 189–204 (2016).

    Article  Google Scholar 

  26. Ayoub, F. et al. Threshold for sand mobility on Mars calibrated from seasonal variations of sand flux. Nat. Commun. 5, 5096 (2014).

  27. Daubar, I. J. et al. Changes in blast zone albedo patterns around new Martian impact craters. Icarus 267, 86–105 (2016).

    Article  Google Scholar 

  28. Wells, E. N., Veverka, J. & Thomas, P. Mars: experimental study of albedo changes caused by dust fallout. Icarus 58, 331–338 (1984).

    Google Scholar 

  29. Leighton, R. B. & Murray, B. C. Behavior of carbon dioxide and other volatiles on Mars. Science 153, 136–144 (1966).

    Article  Google Scholar 

  30. Mellon, M. T., Feldman, W. C. & Prettyman, T. H. The presence and stability of ground ice in the southern hemisphere of Mars. Icarus 169, 324–340 (2004).

    Article  Google Scholar 

  31. Möhlmann, D. T. F. & Thomsen, K. Properties of cryobrines on Mars. Icarus 212, 123–130 (2011).

    Article  Google Scholar 

  32. Toner, J. D. & Catling, D. C. Water activities of NaClO4, Ca(ClO4)2, and Mg(ClO4)2 brines from experimental heat capacities: water activity >0.6 below 200 K. Geochim. Cosmochim. Acta 181, 164–174 (2016).

    Article  Google Scholar 

  33. MARSTHERM thermal model. https://marstherm.boulder.swri.edu/index.php, run 29 November 2016.

  34. Zent, A. P., Hecht, M. H., Hudson, T. L., Wood, S. E. & Chevrier, V. F. A revised calibration function and results for the Phoenix mission TECP relative humidity sensor. J. Geophys. Res. https://doi.org/10.1002/2015JE004933 (2016).

  35. Wang, A. et al. Atmosphere–surface H2O exchange to sustain the Recurring Slope Lineae (RSL) on Mars. Lunar Planet. Sci. Conf. 48, 2351 (2017).

    Google Scholar 

  36. Kossacki, K. J. & Markiewicz, W. J. Seasonal flows on dark Martian slopes, thermal condition for liquescence of salts. Icarus 233, 126–130 (2014).

    Article  Google Scholar 

  37. Farrell, W. M. et al. Is the Martian water table hidden from radar view? Geophys. Res. Lett. https://doi.org/10.1029/2009GL038945 (2009).

  38. Stillman, D. E. & Grimm, R. E. Radar penetrates only the youngest geologic units on Mars. J. Geophys. Res. 116, E03001 (2011).

    Google Scholar 

  39. Andrews-Hanna, J. C., Zuber, M. T., Arvidson, R. E. & Wiseman, S. M. Early Mars hydrology: Meridiani playa deposits and the sedimentary record of Arabia Terra. J. Geophys. Res. https://doi.org/10.1029/2009JE003485 (2010).

  40. Massé, M. et al. Transport processes induced by metastable boiling water under Martian surface conditions. Nat. Geosci. 9, 425–428 (2016).

    Article  Google Scholar 

  41. Arvidson, R. E., Gooding, J. L. & Moore, H. J. The Martian surface as imaged, sampled, and analyzed by the Viking landers. Rev. Geophys. 27, 39–60 (1989).

    Article  Google Scholar 

  42. McDonald, R. R. & Anderson, R. S. Constraints on eolian grain flow dynamics through laboratory experiments on sand slopes. J. Sediment. Res. 66, 642–653 (1996).

    Google Scholar 

  43. Takagi, D., McElwaine, J. N. & Huppert, H. E. Shallow granular flows. Phys. Rev. E 83, 031306 (2011).

    Article  Google Scholar 

  44. Ewing, R. C. et al. Sedimentary processes at the Bagnold Dunes: implications for the eolian rock record of Mars. J. Geophys. Res. Planets https://doi.org/10.1002/2017JE005324 (in the press).

  45. Hecht, M. H. et al. Detection of perchlorate and the soluble chemistry of Martian soil at the Phoenix lander site. Science 325, 64–67 (2009).

    Article  Google Scholar 

  46. Christensen, P. R. et al. Mars Global Surveyor Thermal Emission Spectrometer experiment: investigation description and surface science results. J. Geophys. Res. 106, 23823–23871 (2001).

    Article  Google Scholar 

  47. Kinch, K. M. et al. Dust deposition on the decks of the Mars Exploration Rovers: 10 years of dust dynamics on the Panoramic Camera calibration targets. Earth Space Sci. 2, 144–172 (2015).

    Article  Google Scholar 

  48. Lapotre, M. G. A. et al. Large wind ripples on Mars: a record of atmospheric evolution. Science 353, 55–58 (2016).

    Article  Google Scholar 

  49. Greeley, R. & Iverson, J. D. Wind as a Geologic Process (Cambridge Univ. Press, Cambridge, 1985).

  50. Ojha, L. et al. Spectral constraints on the formation mechanism of recurring slope lineae. Geophys. Res. Lett. https://doi.org/10.1002/2013GL057893 (2013).

  51. Möhlmann, D. T. F. The influence of van der Waals forces on the state of water in the shallow subsurface of Mars. Icarus 195, 131–139 (2008).

    Article  Google Scholar 

  52. Sizemore, H. G., Zent, A. P. & Rempel, A. W. Initiation and growth of Martian ice lenses. Icarus 251, 191–210 (2015).

    Article  Google Scholar 

  53. Rummel, J. D. et al. A new analysis of Mars ‘Special Regions’: findings of the second MEPAG Special Regions Science Analysis Group (SR-SAG2). Astrobiology 14, 887–968 (2014).

    Article  Google Scholar 

  54. Kirk, R. L. et al. Ultrahigh resolution topographic mapping of Mars with MRO HiRISE stereo images: meter-scale slopes of candidate Phoenix landing sites. J. Geophys. Res. 113, E00A24 (2008).

    Article  Google Scholar 

  55. McEwen, A. S. et al. Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE). J. Geophys. Reshttps://doi.org/10.1029/2005JE002605 (2007).

  56. Schaefer, E. I., McEwen, A. S., Mattson, S. & Ojha, L. Quantifying the behavior of recurring slope lineae (RSL). Lunar Planet. Sci. Conf. 46, 2930 (2015).

    Google Scholar 

Download references

Acknowledgements

Observation planning was funded by the MRO project, and analysis by NASA grants NNX13AK01G and NNX14AO21G. We thank NASA/JPL/University of Arizona and the MRO/HiRISE project for collecting and processing data, the University of Arizona for producing DTMs, and NASA for supporting extended mission investigations. D. Stillman provided helpful comments.

Author information

Authors and Affiliations

Authors

Contributions

A.S.M., C.M.D. and M.C. planned many of the HiRISE observations to locate and study RSL. C.M.D. designed the study and gathered the slope data. A.O. and M.C. made observations of uphill ripple movement. M.C. assisted with DTM production. All authors contributed to discussion, interpretation and writing.

Corresponding author

Correspondence to Colin M. Dundas.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

GranularRSL_SOM

Supplementary Table 1; Supplementary Figures S1–S4; and caption information for the supplementary Movies 1–2 animations provided as separate files. (Animations S1–S2)

Animation1_Dune_avalanche_lineae_27N.gif

Animated GIF showing avalanche features on a sand dune slipface, to be compared with RSL

Animation2_Coprates_ripples.gif

Animated GIF showing upslope movement of ripples at one RSL location

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Dundas, C.M., McEwen, A.S., Chojnacki, M. et al. Granular flows at recurring slope lineae on Mars indicate a limited role for liquid water. Nature Geosci 10, 903–907 (2017). https://doi.org/10.1038/s41561-017-0012-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41561-017-0012-5

This article is cited by

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