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.

  • Letter
  • Published:

The loss of ions from Venus through the plasma wake

An Author Correction to this article was published on 09 May 2022

This article has been updated


Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth’s also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System1. Present-day thermal escape is low for all atmospheric species. However, hydrogen can escape by means of collisions with hot atoms from ionospheric photochemistry2, and although the bulk of O and O2 are gravitationally bound, heavy ions have been observed to escape3 through interaction with the solar wind. Nevertheless, their relative rates of escape, spatial distribution, and composition could not be determined from these previous measurements. Here we report Venus Express measurements showing that the dominant escaping ions are O+, He+ and H+. The escaping ions leave Venus through the plasma sheet (a central portion of the plasma wake) and in a boundary layer of the induced magnetosphere. The escape rate ratios are Q(H+)/Q(O+) = 1.9; Q(He+)/Q(O+) = 0.07. The first of these implies that the escape of H+ and O+, together with the estimated escape of neutral hydrogen and oxygen, currently takes place near the stoichometric ratio corresponding to water.

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

Access options

Buy this article

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

Figure 1: Venus Express orbit, and plasma and magnetic field measurements on 2006 December 12.
Figure 2: Composition and energy distribution of the escaping plasma in three spatial regions.
Figure 3: Spatial distribution of the escaping plasma.

Similar content being viewed by others

Change history


  1. Donahue, T. M., Grinspoon, D. H., Hartle, R. R. & Hodges, R. R. in Venus II: Geology, Geophysics, Atmosphere, and Solar Wind Environment (eds Bougher, W. W., Hunten, D. M. & Phillips, R. J.) 385–414 (Univ. of Arizona Press, Tucson, AZ, 1997)

    Google Scholar 

  2. Nagy, A. F., Cravens, T. E., Lee, J. H. & Stewart, A. I. P. Hot oxygen atoms in the upper atmosphere of Venus. Geophys. Res. Lett.8, 629–632 (1981)

    Article  ADS  CAS  Google Scholar 

  3. Mihalov, J. D. & Brace, A. The distant interplanetary wake of Venus: Plasma observations from Pioneer Venus. J. Geophys. Res.87, 9045–9053 (1982)

    Article  ADS  Google Scholar 

  4. Intrilligator, D. S., Wolf, J. H. & Michalov, J. D. The Pioneer Venus orbiter plasma analyzer experiment. IEEE Trans. Geosci. Remote Sens.GE-18, 39–43 (1980)

    Article  ADS  Google Scholar 

  5. Kasprzak, W. T., Niemann, H. B., Hedin, A. E., Bougher, S. W. & Hunten, D. M. Neutral composition measurements by the Pioneer Venus neutral mass spectrometer during re-entry. Geophys. Res. Lett.20, 2747–2750 (1993)

    Article  ADS  CAS  Google Scholar 

  6. Intriligator, D. S. Results of the first statistical studies of Pioneer Venus plasma observations in the distant Venus tail: Evidence for a hemispheric asymmetry in the pickup of ionospheric ions. Geophys. Res. Lett.16, 167–170 (1989)

    Article  ADS  CAS  Google Scholar 

  7. Barabash, S. et al. The Analyser of Space Plasmas and Energetic Atoms (ASPERA-4) for the Venus Express mission. Planet. Space Sci.55, 1772–1792 (2007)

    Article  ADS  CAS  Google Scholar 

  8. Zhang, T. L. et al. Magnetic field investigation of the Venus plasma environment: expected new results. Planet. Space Sci.54, 1336–1343 (2006)

    Article  ADS  Google Scholar 

  9. Zhang, T. L. et al. Little or no solar wind enters Venus’ atmosphere at solar minimum. Nature 10.1038/nature06026 (this issue).

  10. Brace, L. H., Theis, R. F. & Hoegy, W. R. Plasma clouds above the ionopause of Venus and their implications. Planet. Space Sci.30, 29–37 (1982)

    Article  ADS  Google Scholar 

  11. Hartle, R. E. & Grebowsky, J. M. Planetary loss from light ion escape on Venus. Adv. Space Res.15, 117–122 (1995)

    Article  ADS  CAS  Google Scholar 

  12. Luhmann, J. G., Ledvina, S. A., Lyon, J. G. & Russell, C. T. Venus O+ pickup ions: Collected PVO results and expectations for Venus Express. Planet. Space Sci.54, 1457–1471 (2006)

    Article  ADS  CAS  Google Scholar 

  13. Fox, J. L. Advances in the aeronomy of Venus and Mars. Adv. Space Res.33, 132–139 (2004)

    Article  ADS  CAS  Google Scholar 

  14. Lammer, H. et al. Loss of hydrogen and oxygen from the upper atmosphere of Venus. Planet. Space Sci.54, 1445–1456 (2006)

    Article  ADS  CAS  Google Scholar 

  15. McElroy, M. B., Prather, M. J. & Rodriguez, J. M. Loss of oxygen from Venus. Geophys. Res. Lett.9, 649–651 (1982)

    Article  ADS  CAS  Google Scholar 

  16. von Zahn, U., Kumar, S., Niemann, H. & Prinn, R. in Venus (eds Hunten, D. M., Colin, L., Donahue, T. M. & Moroz, V. I.) 299–430 (Univ. of Arizona Press, Tucson, AZ, 1983)

    Google Scholar 

  17. Lammer, H. et al. Loss of water from Mars: Implications for the oxidation of the soil. Icarus165, 9–25 (2003)

    Article  ADS  CAS  Google Scholar 

  18. Luhmann, J. G., Kasprzak, W. T. & Russell, C. T. Space weather at Venus and its potential consequences for atmosphere evolution. J. Geophys Res.112 E04s10 10.1029/2006JE002820 (2007)

    Google Scholar 

  19. McComas, D. J., Spence, H. E., Russell, C. T. & Saunders, M. A. The average magnetic field draping and consistent plasma properties of the Venus magnetotail. J. Geophys. Res.91, 7939–7953 (1986)

    Article  ADS  Google Scholar 

  20. Barabash, S., Fedorov, A., Lundin, R. & Sauvaud, J.-A. Martian atmospheric erosion rates. Science315, 501–503 (2007)

    Article  ADS  CAS  Google Scholar 

  21. Krasnopolsky, V. A. & Gladstone, G. R. Helium on Mars and Venus: EUVE observations and modeling. Icarus176, 395–407 (2005)

    Article  ADS  Google Scholar 

  22. Zhang, T. L., Luhmann, J. G. & Russell, C. T. The solar cycle dependence of the location and shape of the Venus bow shock. J. Geophys. Res.95, 14961–14967 (1990)

    Article  ADS  Google Scholar 

  23. Zhang, T. L., Luhmann, J. G. & Russell, C. T. The magnetic barrier at Venus. J. Geophys. Res.96, 11145–11153 (1991)

    Article  ADS  Google Scholar 

Download references


We thank the European Space Agency for providing the Venus Express opportunity, and national space agencies and organizations for supporting the investigators who contributed to the success of the Venus Express plasma package.

Author Contributions S.B. is the principal investigator of the Venus Express plasma package, Analyser of Space Plasmas and Energetic Atoms (ASPERA)-4. J.A.S. is the co-principal investigator. A.F. is the leading co-investigator of the ion mass analyser of ASPERA-4. A.C. is the leading co-investigator of the electron spectrometer of ASPERA-4. T.L.Z. is the principal investigator of the magnetometer. The remaining authors are co-investigators on either of the plasma analyser or the magnetometer investigations.

Author information

Authors and Affiliations


Corresponding author

Correspondence to S. Barabash.

Supplementary information

Supplementary Information

The file contains additional information for figure legends. (PDF 27 kb)

Rights and permissions

Reprints and permissions

About this article

Cite this article

Barabash, S., Fedorov, A., Sauvaud, J. et al. The loss of ions from Venus through the plasma wake. Nature 450, 650–653 (2007).

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