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Discovery of calcium in Mercury's atmosphere

Nature volume 404, pages 159–161 (2000)Cite this article

Abstract

The composition and evolutionary history of Mercury's crust are not well determined1,2. The planet as a whole has been predicted3 to have a refractory, anhydrous composition: rich in Ca, Al, Mg and Fe, but poor in Na, K, OH, and S. Its atmosphere is believed to be derived in large part from the surface materials. A combination of effects that include impact vaporization (from infalling material), volatile evaporation, photon-stimulated desorption and sputtering releases material from the surface to form the atmosphere. Sodium and potassium have already been observed in Mercury's atmosphere4,5,6, with abundances that require a volatile-rich crust7. The sodium probably results from photon-stimulated desorption8,9, and has a temperature of 1,500 K (ref. 10). Here we report the discovery of calcium in the atmosphere near Mercury's poles. The column density is very low and the temperature is apparently very high (12,000 K). The localized distribution and high temperature, if confirmed, suggest that the atmospheric calcium may arise from surface sputtering by ions, which enter Mercury's auroral zone. The low abundance of atmospheric Ca may indicate that the regolith is rarefied in calcium.

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Figure 1: The observing geometry, samples of the CaI emission spectra, and the HIRES instrumental line profile.
Figure 2: The spatial variation of the column emission intensity, emission line width, and residual Doppler-shift of Ca in Mercury's atmosphere.

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References

  1. Goettel, K. A. in Mercury 613–621 (Univ. Arizona Press, Tucson, 1988).

    Google Scholar 

  2. Lewis, J. S. in Mercury 651–666 (Univ. Arizona Press, Tucson, 1988).

    Google Scholar 

  3. Lewis, J. S. Metal/silicate fractionation in the solar system. Earth Planet Sci. 15, 286–290 ( 1992).

    Article  ADS  Google Scholar 

  4. Potter, A. E. & Morgan, T. H. Discovery of sodium in the atmosphere of Mercury. Science 229, 651– 653 (1985).

    Article  ADS  CAS  Google Scholar 

  5. Potter, A. E. & Morgan, T. H. Potassium in the atmosphere of Mercury. Icarus 67, 336– 340 (1986).

    Article  ADS  CAS  Google Scholar 

  6. Sprague, A. L. et al. Distribution and abundance of sodium in Mercury's atmosphere, 1985–1988. Icarus 129, 506– 527 (1997).

    Article  ADS  CAS  Google Scholar 

  7. Killen, R. M. & Morgan, T. H. Maintaining the Na atmosphere of Mercury. Icarus 101, 293– 312 (1993).

    Article  ADS  CAS  Google Scholar 

  8. McGrath, M. A., Johnson, R. E. & Lanzerotti, L. J. Sputtering of sodium on the planet Mercury. Nature 323, 694–696 ( 1986).

    Article  ADS  CAS  Google Scholar 

  9. Yakshinskiy, B. V. & Madey, T. E. Photon-stimulated desorption as a substantial source of sodium in the lunar atmosphere. Nature 400, 642–644 ( 1999).

    Article  ADS  CAS  Google Scholar 

  10. Killen, R. M., Potter, A. E., Fitzsimmons, A. & Morgan, T. H. Sodium D2 line profiles: clues to the temperature structure of Mercury's exosphere. Planet. Space Sci. 47, 1449– 1458 (1999).

    Article  ADS  CAS  Google Scholar 

  11. Vogt, S. S. et al. HIRES: the high-resolution echelle spectrometer on the Keck 10-m telescope. Proc. S.P.I.E. 2198, 362 (1994).

    CAS  Google Scholar 

  12. Chamberlain, J. W. & Hunten, D. M. Theory of Planetary Atmospheres (Academic Press, Orlando, 1987).

    Google Scholar 

  13. Kurucz, R. L., Furenlid, I., Brault, J. & Testerman, L. Solar Flux Atlas From 296 to 1300 nm, National Solar Observatory Atlas No. 1 (Harvard Univ. Press, Boston, 1984).

    Google Scholar 

  14. Cheng, A. F., Johnson, R. E., Krimigis, S. M. & Lanzerotti, L. J. Magnetosphere, exosphere and surface of Mercury. Icarus 71, 430–440 (1987).

    Article  ADS  CAS  Google Scholar 

  15. Madey, T. E., Yakshinsky, V. N., Ageev, V. N. & Johnson, R. E. Desorption of alkali atoms and ions from oxide surfaces: relevance to origins of Na and K atmospheres of Mercury and the Moon. J. Geophys. Res. 103, 5873–5887 ( 1998).

    Article  ADS  CAS  Google Scholar 

  16. Chamberlain, J. W. Spectral line profiles for a planetary corona. J. Geophys. Res. 81, 1774–1776 ( 1976).

    Article  ADS  Google Scholar 

  17. Elphic, R. C. et al. Lunar surface composition and solar wind-induced secondary ion mass spectrometry. Geophys. Res. Lett. 18, 2165–2168 (1991).

    Article  ADS  CAS  Google Scholar 

  18. Sugita, S., Schultz, P. H. & Adams, M. A. In situ temperature measurements of impact-induced vapor clouds with spectroscopic methods. Proc. Lunar Planet. Sci. Conf. 28, 1393–1394 ( 1997).

    ADS  Google Scholar 

  19. Morgan, T. H. & Killen, R. M. A non-stoichiometric model of the composition of the atmospheres of Mercury and the Moon. Planet. Space Sci. 45, 81–94 ( 1997).

    Article  ADS  CAS  Google Scholar 

  20. Sprague, A. L., Koslowski, R. W. H., Hunten, D. M. & Grosse, F. A. An upper limit on neutral calcium in Mercury's atmosphere. Icarus 104, 33–37 ( 1993).

    Article  ADS  CAS  Google Scholar 

  21. Sprague, A. L., Nash, D. B., Witteborn, F. C. & Cruikshank, D. P. Mercury's feldspar connection: mid-IR measurements suggest plagioclase. Adv. Space Res. 19, 1507–1510 (1997).

    Article  ADS  CAS  Google Scholar 

  22. Jeanloz, R., Mitchell, D. L., Sprague, A. L. & dePater, I. Evidence for a basalt free surface on Mercury and implications for internal heat. Science 268, 1455– 1457 (1995).

    Article  ADS  CAS  Google Scholar 

  23. Sprague, A. L., Schmitt, W. J. & Hill, R. E. Mercury: Sodium atmospheric enhancements, radar bright spots and surface features. Icarus 136, 60–68 (1998).

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

The data presented here were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W.M. Keck Foundation. We are grateful to the WMKO Observing Assistants for their help while conducting the observations. R.M.K. acknowledges the support of a NASA grant.

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Authors and Affiliations

  1. W. M. Keck Observatory, CARA, 65-1120 Mamalahoa Highway, Kamuela, 96743, Hawaii, USA

    Thomas A. Bida

  2. Southwest Research Institute, 6220 Culebra Road, San Antonio, 78228-0510 , Texas, USA

    Rosemary M. Killen

  3. NASA Headquarters, 300 E. Street NW, Washington, 20546-1113, District of Columbia , USA

    Thomas H. Morgan

Authors
  1. Thomas A. Bida
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  2. Rosemary M. Killen
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  3. Thomas H. Morgan
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Correspondence to Thomas A. Bida.

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Bida, T., Killen, R. & Morgan, T. Discovery of calcium in Mercury's atmosphere. Nature 404, 159–161 (2000). https://doi.org/10.1038/35004521

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