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Radio Science Experiment (GRE)

NSSDC ID: 1985-056A-11
Mission Name: Giotto
Principal Investigator: Prof. Peter Edenhofer


The scientific objectives of this experiment were to determine both the columnar electron content of Comet Halley's ionosphere and the cometary mass fluence from atmospheric drag by using the radio signals from Giotto during the Halley encounter on 13--14 March 1986. The measurements of cometary electron content and mass fluence were inverted to derive the spatial distribution of the electron and mass (dust and gas) density within Halley's coma. This experiment was an occultation-type, remote-sensing experiment which relied on the propagation effects of electromagnetic waves. The experiment took measurements of the phase (Doppler) shifts of the downlink carrier signals both at S-band (2.3 GHz) and X-band (8.4 GHz) as a function of time during the Halley encounter.

Alternate Names

  • GRE

Funding Agency

  • European Space Agency (International)


  • Planetary Science: Small Bodies

Additional Information

Questions or comments about this experiment can be directed to: Dr. David R. Williams.



NameRoleOriginal AffiliationE-mail
Dr. Hans E. VollandCo-InvestigatorUniversitat
Dr. Herbert PorscheCo-InvestigatorDeutsche Forschungsenstalt fuer Luft-und Raumfahrt 
Dr. Michael K. BirdCo-InvestigatorUniversitat
Dr. Pasquale B. EspositoCo-InvestigatorNASA Jet Propulsion
Prof. Peter EdenhoferGeneral ContactRuhr-Universitat
Prof. H. BuschertCo-InvestigatorRuhr-Universitat Bochum 

Selected References

Edenhofer, P., et al., The Giotto radio-science experiment, In--The Giotto Mission--Its Scientific Investigations, ESA SP-1077, edited by R. Reinhard and B. Battrick, pp. 173-186, Mar. 1986.

Edenhofer, P., et al., First results from the Giotto radio-science experiment, Nature, 321, No. 6067, 355-361, May 1986.

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