Comet Halley | Published:

In situ gas and ion measurements at comet Halley

Naturevolume 321pages326329 (1986) | Download Citation



The neutral mass spectrometer experiment (NMS) carried by the Giotto spacecraft was designed to determine the abundances and the chemical, elemental and isotopic composition of the gases and low-energy ions in the coma of comet Halley. Its first results show the predominance of water vapour (80% by volume). Preliminary evaluation of the data yields an H2O density of 4.7 × 107 molecules cm−3 at 1,000 km, a neutral gas expansion velocity of 0.9 km s−1 and a total gas production rate of 6.9 × 1029 molecules s−1. The photodestruction scale length for H2O was 3.9 × 104 km. Limits on the abundances of CO2, NH3 and CH4 relative to H2O are given. The contact surface was located at 4,700±200 km, as observed from a change in ion temperature. The water-group ions H3O+, H2O+ and OH+ have been unambiguously identified, along with the ions 12C+, 12CH+, 16O+, Na+, 12C2+, 32S+, 34S+ and 56Fe+. The 34S+/32S+ ratio is 0.045±0.010. General features of the low-energy ion flow at large distances from the nucleus are presented.


  1. 1

    Krankowsky, D. et al. Eur. Space Ag. spec. Publ. 1077, 109–128 (1986).

  2. 2

    Huebner, W. F. & Carpenter, C. W. Los Alamos natn. Lab. Rep. No. LA-8085-MS (1979).

  3. 3

    Marconi, L. M. & Mendis, D. A. Astrophys. J. 287, 445–454 (1984).

  4. 4

    Bossy, L. & Nicolet, M. Planet. Space Sci. 29, 907–914 (1981).

Download references

Author information

Author notes

    • U. Herrmann

    Present address: Generaldirektion PIT, CH-3000, Bern, 29, Switzerland


  1. Max-Planck-Institut für Kernphysik, Postfach 103980, Saupfercheckweg, D-6900, Heidelberg, 1, FRG

    • D. Krankowsky
    • , P. Lämmerzahl
    • , I. Herrwerth
    •  & J. Woweries
  2. Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012, Bern, Switzerland

    • P. Eberhardt
    • , U. Dolder
    • , U. Herrmann
    •  & W. Schulte
  3. Centre de Recherches en Physique de l'Environement Terrestre et Planétaire, CNET-CNRS, 4 avenue de Neptune, 94107, Saint-Maur des Fossés, Paris, France

    • J. J. Berthelier
    •  & J. M. Illiano
  4. University of Texas at Dallas, Richardson, Texas, 75083-0688, USA

    • R. R. Hodges
    •  & J. H. Hoffman


  1. Search for D. Krankowsky in:

  2. Search for P. Lämmerzahl in:

  3. Search for I. Herrwerth in:

  4. Search for J. Woweries in:

  5. Search for P. Eberhardt in:

  6. Search for U. Dolder in:

  7. Search for U. Herrmann in:

  8. Search for W. Schulte in:

  9. Search for J. J. Berthelier in:

  10. Search for J. M. Illiano in:

  11. Search for R. R. Hodges in:

  12. Search for J. H. Hoffman in:

About this article

Publication history



Issue Date


Further reading


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.