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.

Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere



Almost a decade after methane was first reported in the atmosphere of Mars1,2 there is an intensive discussion about both the reliability of the observations3,4—particularly the suggested seasonal and latitudinal variations5,6—and the sources of methane on Mars. Given that the lifetime of methane in the Martian atmosphere is limited1,6, a process on or below the planet’s surface would need to be continuously producing methane. A biological source would provide support for the potential existence of life on Mars, whereas a chemical origin would imply that there are unexpected geological processes7. Methane release from carbonaceous meteorites associated with ablation during atmospheric entry is considered negligible8. Here we show that methane is produced in much larger quantities from the Murchison meteorite (a type CM2 carbonaceous chondrite) when exposed to ultraviolet radiation under conditions similar to those expected at the Martian surface. Meteorites containing several per cent of intact organic matter reach the Martian surface at high rates9, and our experiments suggest that a significant fraction of the organic matter accessible to ultraviolet radiation is converted to methane. Ultraviolet-radiation-induced methane formation from meteorites could explain a substantial fraction of the most recently estimated atmospheric methane mixing ratios3,4. Stable hydrogen isotope analysis unambiguously confirms that the methane released from Murchison is of extraterrestrial origin. The stable carbon isotope composition, in contrast, is similar to that of terrestrial microbial origin; hence, measurements of this signature in future Mars missions may not enable an unambiguous identification of biogenic methane.

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

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



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

Figure 1: Methane mixing ratios during ultraviolet irradiation of Murchison meteorite samples in a photochemical reactor.
Figure 2: Methane emission rates from ultraviolet irradiation of Murchison meteorite samples as a function of temperature and at different pressures.
Figure 3: Stable carbon and hydrogen isotope composition of CH 4 from terrestrial sources and from carbonaceous chondrites.


  1. Krasnopolsky, V. A., Maillard, J. P. & Owen, T. C. Detection of methane in the Martian atmosphere: evidence for life? Icarus 172, 537–547 (2004)

    Article  CAS  ADS  Google Scholar 

  2. Formisano, V., Atreya, S., Encrenaz, T., Ignatiev, N. & Giuranna, M. Detection of methane in the atmosphere of Mars. Science 306, 1758–1761 (2004)

    Article  CAS  ADS  Google Scholar 

  3. Zahnle, K., Freedman, R. S. & Catling, D. C. Is there methane on Mars? Icarus 212, 493–503 (2011)

    Article  CAS  ADS  Google Scholar 

  4. Krasnopolsky, V. A. Search for methane and upper limits to ethane and SO2 on Mars. Icarus 217, 144–152 (2012)

    Article  CAS  ADS  Google Scholar 

  5. Mumma, M. J. et al. Strong release of methane on Mars in northern summer 2003. Science 323, 1041–1045 (2009)

    Article  CAS  ADS  Google Scholar 

  6. Lefèvre, F. & Forget, F. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics. Nature 460, 720–723 (2009)

    Article  ADS  Google Scholar 

  7. Etiope, G., Oehler, D. Z. & Allen, C. C. Methane emissions from Earth's degassing: implications for Mars. Planet. Space Sci. 59, 182–195 (2011)

    Article  CAS  ADS  Google Scholar 

  8. Court, R. W. & Sephton, M. A. Investigating the contribution of methane produced by ablating micrometeorites to the atmosphere of Mars. Earth Planet. Sci. Lett. 288, 382–385 (2009)

    Article  CAS  ADS  Google Scholar 

  9. Flynn, G. J. & McKay, D. S. An assessment of the meteoritic contribution to the Martian soil. J. Geophys. Res. B 95, 14497–14509 (1990)

    Article  ADS  Google Scholar 

  10. Geminale, A., Formisano, V. & Sindoni, G. Mapping methane in Martian atmosphere with PFS-MEX data. Planet. Space Sci. 59, 137–148 (2011)

    Article  CAS  ADS  Google Scholar 

  11. Shkrob, I. A., Chemerisov, S. D. & Marin, T. W. Photocatalytic decomposition of carboxylated molecules on light-exposed Martian regolith and its relation to methane production on Mars. Astrobiology 10, 425–436 (2010)

    Article  CAS  ADS  Google Scholar 

  12. Schuerger, A. C., Clausen, C. & Britt, D. Methane evolution from UV-irradiated spacecraft materials under simulated Martian conditions: implications for the Mars Science Laboratory (MSL) mission. Icarus 213, 393–403 (2011)

    Article  CAS  ADS  Google Scholar 

  13. Atreya, S. K., Mahaffy, P. R. & Wong, A. S. Methane and related trace species on Mars: origin, loss, implications for life, and habitability. Planet. Space Sci. 55, 358–369 (2007)

    Article  CAS  ADS  Google Scholar 

  14. Vigano, I. et al. Effect of UV radiation and temperature on the emission of methane from plant biomass and structural components. Biogeosciences 5, 937–947 (2008)

    Article  CAS  ADS  Google Scholar 

  15. McLeod, A. R. et al. Ultraviolet radiation drives methane emissions from terrestrial plant pectins. New Phytol. 180, 124–132 (2008)

    Article  CAS  Google Scholar 

  16. Cockell, C. S. et al. The ultraviolet environment of Mars: biological implications past, present, and future. Icarus 146, 343–359 (2000)

    Article  CAS  ADS  Google Scholar 

  17. ten Kate, I. L. et al. Amino acid photostability on the Martian surface. Meteorit. Planet. Sci. 40, 1185–1193 (2005)

    Article  CAS  ADS  Google Scholar 

  18. Stoker, C. R. & Bullock, M. A. Organic degradation under simulated Martian conditions. J. Geophys. Res. E 102, 10881–10888 (1997)

    Article  CAS  ADS  Google Scholar 

  19. Chun, S. F. S., Pang, K. D., Cutts, J. A. & Ajello, J. M. Photocatalytic oxidation of organic compounds on Mars. Nature 274, 875–876 (1978)

    Article  CAS  ADS  Google Scholar 

  20. Flynn, G. J. The delivery of organic matter from asteroids and comets to the early surface of Mars. Earth Moon Planets 72, 469–474 (1996)

    Article  CAS  ADS  Google Scholar 

  21. Wong, N. et al. in Proceedings of the Twelfth ASCE Aerospace Division International Conference on Engineering, Science, Construction, and Operations in Challenging Environments and the Fourth NASA/ARO/ASCE Workshop on Granular Materials in Lunar and Martian Exploration (eds Song, G. & Malla, R.B. ) 29–35 (ASCE, 2010)

  22. Butterworth, A. L., Aballain, O., Chappellaz, J. & Sephton, M. A. Combined element (H and C) stable isotope ratios of methane in carbonaceous chondrites. Mon. Not. R. Astron. Soc. 347, 807–812 (2004)

    Article  CAS  ADS  Google Scholar 

  23. Bartoszek, M., Wecks, M., Jakobs, G. & Mohlmann, D. Photochemically induced formation of Mars relevant oxygenates and methane from carbon dioxide and water. Planet. Space Sci. 59, 259–263 (2011)

    Article  CAS  ADS  Google Scholar 

  24. Allen, C. C., Gooding, J. L., Jercinovic, M. & Keil, K. Altered basaltic glass — a terrestrial analog to the soil of Mars. Icarus 45, 347–369 (1981)

    Article  CAS  ADS  Google Scholar 

  25. Kieffer, H. H. et al. Thermal and albedo mapping of Mars during the Viking Primary Mission. J. Geophys. Res. 82, 4249–4291 (1977)

    Article  CAS  ADS  Google Scholar 

  26. Robert, F. & Epstein, S. The concentration and isotopic composition of hydrogen, carbon and nitrogen in carbonaceous meteorites. Geochim. Cosmochim. Acta 46, 81–95 (1982)

    Article  CAS  ADS  Google Scholar 

  27. Sephton, M. A. et al. Investigating the variations in carbon and nitrogen isotopes in carbonaceous chondrites. Geochim. Cosmochim. Acta 67, 2093–2108 (2003)

    Article  CAS  ADS  Google Scholar 

  28. Sephton, M. A. Organic compounds in carbonaceous meteorites. Nat. Prod. Rep. 19, 292–311 (2002)

    Article  CAS  Google Scholar 

  29. Vigano, I. et al. The stable isotope signature of methane emitted from plant material under UV irradiation. Atmos. Environ. 43, 5637–5646 (2009)

    Article  CAS  ADS  Google Scholar 

  30. ten Kate, I. L. Organics on Mars? Astrobiology 10, 589–603 (2010)

    Article  CAS  ADS  Google Scholar 

  31. Navarro-González, R., Vargas, E., de la Rosa, J., Raga, A. C. & McKay, C. P. Reanalysis of the Viking results suggests perchlorate and organics at midlatitudes on Mars. J. Geophys. Res. E 115, 12010, (2010)

  32. 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  CAS  ADS  Google Scholar 

  33. Clark, B. C. & Baird, A. K. Is the Martian lithosphere sulfur rich? J. Geophys. Res. 84, 8395–8403 (1979)

    Article  CAS  ADS  Google Scholar 

Download references


F.K. was supported by the ESF (EURYI award to F.K.) and DFG (KE 884/2-1). Measurements at Utrecht University were funded by the Dutch NWO (grant number 865.07.001). A.M. was supported by the NERC (NE/F020422/1) and a Royal Society Leverhulme Trust senior research fellowship. We thank M. Greule, F. Althoff, A. Jugold, C. Tubbesing and H. F. Schöler for technical support; H. van Weelden from the Utrecht Medical Center for measuring the spectral distribution of the Xe lamp and calibrating the Waldmann ultraviolet meter; C. Brenninkmeijer, J. Lelieveld and C. Cockell for advice; and C. Jäger for providing data on ultraviolet absorption by minerals.

Author information

Authors and Affiliations



F.K., I.V., A.M. and T.R. planned the study. I.V., F.K. and M.F. carried out the experiments. F.K., I.V., A.M., U.O. and T.R. worked on the scientific interpretation and wrote the manuscript.

Corresponding author

Correspondence to Frank Keppler.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Text, Supplementary Figures 1-9, Supplementary Table 1 and Supplementary References. (PDF 709 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Keppler, F., Vigano, I., McLeod, A. et al. Ultraviolet-radiation-induced methane emissions from meteorites and the Martian atmosphere. Nature 486, 93–96 (2012).

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