Discovery of a proton aurora at Mars

Abstract

Proton aurorae are a distinct class of auroral phenomena caused by energetic protons precipitating into a planetary atmosphere. The defining observational signature is atomic hydrogen emissions from the precipitating particles after they obtain an electron from the neutral atmospheric gas, a process known as charge exchange. Until now, proton aurorae have been observed at Earth only. Here, we present evidence of auroral activity driven by precipitating protons at Mars, using observations by the MAVEN spacecraft. We observed transient brightening of upper atmospheric hydrogen Lyman-α emission across the Martian dayside correlated with solar wind activity. The driving mechanism is one not found at Earth and originates from energetic neutral atom production by solar wind protons directly interacting with the extended hydrogen corona surrounding Mars. We characterize this new type of Martian aurora and compare the observed emissions with preliminary modelling guided by simultaneous in situ particle measurements. These observations provide insights into how the solar wind can directly deposit energy into the Martian atmosphere as well as all other planetary objects that are surrounded by a substantial neutral corona exposed to the solar wind.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Mechanism for Martian proton aurorae originating from solar wind charge exchange.
Fig. 2: Limb observations showing the signature of a proton aurora in atomic hydrogen emission.
Fig. 3: Timeline of SWIA penetrating protons and IUVS Lyα enhancements in March–April 2015.
Fig. 4: Observed and modelled Lyα brightness profiles.

References

  1. 1.

    Vegard, L. Hydrogen showers in the auroral region. Nature 144, 1089–1090 (1939).

    ADS  Google Scholar 

  2. 2.

    Eather, R. H. Auroral proton precipitation and hydrogen emissions. Rev. Geophys. 5, 207–285 (1967).

    ADS  Article  Google Scholar 

  3. 3.

    Gérard, J.-C., Hubert, B., Bisikalo, D. V. & Shematovich, V. I. A model of the Lyman line profile in the proton aurora. J. Geophys. Res. 105, 15795–15806 (2000).

    ADS  Article  Google Scholar 

  4. 4.

    Hardy, D. A., Gussenhoven, M. S. & Brautigam, D. A statistical model of auroral ion precipitation. J. Geophys. Res. 94, 370–392 (1989).

    ADS  Article  Google Scholar 

  5. 5.

    Kallio, E. & Barabash, S. Atmospheric effects of precipitating energetic hydrogen atoms on the Martian atmosphere. J. Geophys. Res. 106, 165–177 (2001).

    ADS  Article  Google Scholar 

  6. 6.

    Frey, H. U. et al. Proton aurora in the cusp. J. Geophys. Res. 107, 1091 (2002).

    Article  Google Scholar 

  7. 7.

    Stephan, A. W., Chakrabarti, S. & Cotton, D. M. Evidence of ENA precipitation in the EUV dayglow. Geophys. Res. Lett. 27, 2865–2868 (2000).

    ADS  Article  Google Scholar 

  8. 8.

    Jakosky, B. M. et al. The Mars Atmosphere and Volatile Evolution (MAVEN) mission. Space Sci. Rev. 195, 3–48 (2015).

    ADS  Article  Google Scholar 

  9. 9.

    McClintock, W. E. et al. The Imaging Ultraviolet Spectrograph (IUVS) for the MAVEN mission. Space Sci. Rev. 195, 75–124 (2015).

    ADS  Article  Google Scholar 

  10. 10.

    Anderson, D. E.Jr & Hord, C. W. Mariner 6 and 7 ultraviolet spectrometer experiment: analysis of hydrogen Lyman-alpha data. J. Geophys. Res. 76, 6666–6673 (1971).

    ADS  Article  Google Scholar 

  11. 11.

    Chaufray, J. Y., Bertaux, J. L., Leblanc, F. & Quémerais, E. Observation of the hydrogen corona with SPICAM on Mars Express. Icarus 195, 598–613 (2008).

    ADS  Article  Google Scholar 

  12. 12.

    Chaffin, M. S. et al. Three-dimensional structure in the Mars H corona revealed by IUVS on MAVEN. Geophys. Res. Lett. 42, 9001–9008 (2015).

    ADS  Article  Google Scholar 

  13. 13.

    Halekas, J. S. et al. The Solar Wind Ion Analyzer for MAVEN. Space Sci. Rev. 195, 125–151 (2015).

    ADS  Article  Google Scholar 

  14. 14.

    Halekas, J. S. et al. MAVEN observations of solar wind hydrogen deposition in the atmosphere of Mars. Geophys. Res. Lett. 42, 8901–8909 (2015).

    ADS  Article  Google Scholar 

  15. 15.

    Halekas, J. S. Seasonal variability of the hydrogen exosphere of Mars. J. Geophys. Res. 122, 901–911 (2017).

    Article  Google Scholar 

  16. 16.

    Barth, C. A. et al. Mariner 6 and 7 ultraviolet spectrometer experiment: upper atmosphere data. J. Geophys. Res. 76, 2213–2227 (1971).

    ADS  Article  Google Scholar 

  17. 17.

    Leblanc, F., Chaufray, J. Y., Lilensten, J., Witasse, O. & Bertaux, J.-L. Martian dayglow as seen by the SPICAM UV spectrograph on Mars Express. J. Geophys. Res. 111, E09S11 (2006).

  18. 18.

    Jain, S. K. et al. The structure and variability of Mars upper atmosphere as seen in MAVEN/IUVS dayglow observations. Geophys. Res. Lett. 42, 9023–9030 (2015).

    ADS  Article  Google Scholar 

  19. 19.

    Fang, X., Liemohn, M. W., Kozyra, J. U. & Solomon, S. C. Quantification of the spreading effect of auroral proton precipitation. J. Geophys. Res. 109, A04309 (2004).

    ADS  Google Scholar 

  20. 20.

    Fang, X., Lummerzheim, D. & Jackman, C. H. Proton impact ionization and a fast calculation method. J. Geophys. Res. 118, 5369–5378 (2013).

    Article  Google Scholar 

  21. 21.

    Basu, B., Jasperse, J. R., Robinson, R. M., Vondrak, R. R. & Evans, D. S. Linear transport theory of auroral proton precipitation—a comparison with observations. J. Geophys. Res. 92, 5920–5932 (1987).

    ADS  Article  Google Scholar 

  22. 22.

    Evans, J. S. et al. Retrieval of CO2 and N2 in the Martian thermosphere using dayglow observations by IUVS on MAVEN. Geophys. Res. Lett. 42, 9040–9049 (2015).

    ADS  Article  Google Scholar 

  23. 23.

    Bertaux, J.-L. et al. Discovery of an aurora on Mars. Nature 435, 790–794 (2005).

    ADS  Article  Google Scholar 

  24. 24.

    Schneider, N. M. et al. Discovery of diffuse aurora on Mars. Science 350, aad0313 (2015).

    Article  Google Scholar 

  25. 25.

    Kallio, E. S., Luhmann, J. G. & Barabash, S. Charge exchange near Mars: the solar wind absorption and energetic neutral atom production. J. Geophys. Res. 102, 22183–22197 (1997).

    ADS  Article  Google Scholar 

  26. 26.

    Diéval, C., Kallio, E., Stenberg, G., Barabash, S. & Jarvinen, R. Hybrid simulations of proton precipitation patterns onto the upper atmosphere of Mars. Earth Planets Space 64, 121–134 (2012).

    ADS  Article  Google Scholar 

  27. 27.

    Gunell, H. et al. First ENA observations at Mars: charge exchange ENAs produced in the magnetosheath. Icarus 182, 431–438 (2006).

    ADS  Article  Google Scholar 

  28. 28.

    Gombosi, T. I., Cravens, T. E., Nagy, A. F., Elphic, R. C. & Russell, C. T. Solar wind absorption by Venus. J. Geophys. Res. 85, 7747–7753 (1980).

    ADS  Article  Google Scholar 

  29. 29.

    Simon Wedlund, C. et al. The atmosphere of comet 67P/Churyumov-Gerasimenko diagnosed by charge-exchanged solar wind alpha particles. Astron. Astrophys. 587, A154 (2016).

    Article  Google Scholar 

  30. 30.

    Bertucci, C. et al. Titan’s interaction with the supersonic solar wind. Geophys. Res. Lett. 42, 193–200 (2015).

    ADS  Article  Google Scholar 

  31. 31.

    Vidal-Madjar, A. et al. An extended upper atmosphere around the extrasolar planet HD209458b. Nature 422, 143–146 (2003).

    ADS  Article  Google Scholar 

Download references

Acknowledgements

The MAVEN mission is supported by NASA through the Mars Exploration Program. J.-Y.C., F.M. and F.L. are funded by the programme ‘Systeme Solaire’ of Centre National d’Etudes Spatiales. A.S. is supported by the Belgian Fund for Scientific Research (FNRS).

Author information

Affiliations

Authors

Contributions

J.D., S.K.J. and M.S.C. performed the analysis. X.F. created and ran the precipitating particle transport model used here. J.S.H. provided SWIA measurements and guidance in using them. J.S.E. provided neutral atmosphere airglow retrievals. All authors contributed to the development of the instrument pipeline and/or data acquisition as well as interpretation and presentation of these results.

Corresponding author

Correspondence to J. Deighan.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

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

Supplementary information

Supplementary Information

Supplementary Figures 1–4

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Deighan, J., Jain, S.K., Chaffin, M.S. et al. Discovery of a proton aurora at Mars. Nat Astron 2, 802–807 (2018). https://doi.org/10.1038/s41550-018-0538-5

Download citation

Further reading

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