Letter | Published:

Photocatalytic oxidation of organic compounds on Mars

Nature volume 274, pages 875876 (31 August 1978) | Download Citation

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Abstract

THE non-detection of organic compounds on Mars1 is interesting because there are at least two mechanisms that can produce a contemporary accumulation of these compounds on Mars—photochemical synthesis and meteoritic infall. The synthesis of organic compounds from carbon monoxide and water absorbed in inorganic matrices under UV irradiation and simulated martian conditions has been demonstrated1. By comparison, our Moon has a surface composition that is 1.1% carbonaceous chondrite, due to a meteoritic infall rate about three times less than that on Mars2. As much as 5% of carbonaceous chondrite material is organic3. Assuming a meteoritic influx rate three times that of the Moon, and a reasonable mixing rate with the martian regolith, organic constituents of carbonaceous chondrites should be diluted in the martian soil to concentrations detectable by the Viking gas chromatograph–mass spectrometer (GCMS)1. The results of the Viking GCMS experiments were, therefore, rather surprising. No organic molecules were present in the Viking GCMS samples above concentrations of parts per 109 (ref. 1). Mechanisms have been proposed in which peroxides, superoxides and ozonides formed under UV irradiation oxidise organic compounds4,5. Glow discharge was suggested as the ‘scavenger’ of martian organic matter6. Here, we propose an alternative mechanism for the destruction of organics on Mars—UV-stimulated catalytic oxidation. Our proposal differs from previous ones in that all conditions required for photocatalytic oxidation of organics—gaseous oxygen7, UV irradiation8, and titanium dioxide9,10—have been found to be present in the martian environment.

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References

  1. 1.

    et al. J. geophys. Res. 82, 4641–4658 (1977).

  2. 2.

    Icarus 31, 260–276 (1977).

  3. 3.

    Geochim. cosmochim. Acta 31, 1395–1440 (1967).

  4. 4.

    , & Nature 265, 110–114 (1977).

  5. 5.

    , , , & Science 197, 455–457 (1977).

  6. 6.

    Nature 268, 614 (1977).

  7. 7.

    et al. J. geophys. Res. 82, 4635–4639 (1977).

  8. 8.

    & Icarus 18, 481–488 (1973).

  9. 9.

    & Icarus 30, 63–74 (1977).

  10. 10.

    et al. J. geophys. Res. 82, 4625–4634 (1977).

  11. 11.

    Dokl. Akad. Nauk SSSR 154, 151–154 (1964).

  12. 12.

    & Trans. Faraday Soc. 60, 1007–1016 (1964).

  13. 13.

    , , , & J. Colloid Interface Sci. 39, 79–89 (1972).

  14. 14.

    , & J. Catal. 31, 398–407 (1973).

  15. 15.

    , , Bull Soc. Chim. France 9–10, 1315–1319 (1976).

  16. 16.

    et al. Vacuum Sci. Technol. 9, 947–952 (1971).

  17. 17.

    et al. J. geophys. Res. 82, 4479–4496 (1977).

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Author information

Affiliations

  1. Planetary Science Institute, 283 S. Lake Ave, Suite 218, Pasadena, California 91101

    • SANDY F. S. CHUN
    • , KEVIN D. PANG
    •  & JAMES A. CUTTS
  2. Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91103

    • JOSEPH M. AJELLO

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https://doi.org/10.1038/274875a0

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