Search Publications
Aspects of the major element composition of Halley's dust
Kissel, J.; Jessberger, E. K.; Christoforidis, A.
The chemical composition of the solid grains from comet Halley can be inferred from impact-ionization time-of-flight mass spectrometry. Halley's dust in the vicinity of the VEGA-1 spacecraft is a mixture of a refractory organic component and unequilibrated silicates, but detailed chemical information on individual particles is difficult to extract…
Ion plasma waves in dusty plasmas: Halley's comet
Formisano, V.; Giordano, M.; de Angelis, U.
We investigate ion waves in a plasma in the presence of massive charged dust particles, a common space-plasma component now known to exist also in planetary rings and comets. We derive an equation describing low-frequency electrostatic perturbations on a non-homogeneous background, where the inhomogeneity is due to a distribution of charged grains…
The 2.5-12 µm spectrum of comet halley from the IKS-VEGA experiment
Bibring, J. -P.; Encrenaz, T.; Crovisier, J. +14 more
The infrared instrument IKS flown on board the VEGA space probes was designed for the detection of emission bands of parent molecules, and for a measurement of the size and temperature of the thermal emitting nuclear region. The instrument had three channels with cooled detectors: an "imaging channel" designed to modulate the signal of the nucleus…
Cometary gas and plasma flow with detailed chemistry.
Huebner, W. F.; Wegmann, R.; Schmidt, H. U. +1 more
This paper describes recent hydrodynamic and magnetohydrodynamic (MHD) simulations for the gas and plasma flow around a comet with detailed photo and chemical reaction network of 59 neutral and 76 ionized chemical species. The method allows for a separate energy balance of the electrons, separate flow of neutral gas, fast neutral atomic and molecu…
Optical polarimetry of P/Halley - Synthesis of the measurements in the continuum
Le Borgne, J. -F.; Bastien, P.; Levasseur-Regourd, A. C. +2 more
Ground-based observations of the linear polarization of P/Halley in the continuum by several independent groups of observers are analysed in common to produce synthetic polarization data. Curves of polarization as a function of phase angle are derived for the bright envelope around the nucleus, for the dust grains after they emerge from this envel…
The ionopause transition and boundary layers at comet Halley from Giotto magnetic field observations
Neubauer, F. M.
Giotto magnetic field observations at a time resolution of 28.24 vectors per second in the innermost part of the interaction region of comet Halley with the solar wind have yielded the following results: (1) The outer boundary of the cavity, the ionopause, has a thickness of 25 km only, both inbound and outbound, and magnetic field magnitude drops…
Cometary H2 + and solar wind He2+ dynamics across the Halley cometopause
Balsiger, H.; Geiss, J.; Ip, W. -H. +4 more
Two Mass/Charge (M/Q) ≈ 2 distributions were observed by the Giotto Ion Mass Spectrometer/High Energy Range Spectrometer (IMS/HERS) during the encounter with comet Halley. The first, present throughout the encounter, is identified as solar wind He2+. The second, detectable only within ∼6 × 105 km of the nucleus, is identified…
On the rotation axis of comet Halley
Keller, H. U.; Thomas, N.
The observations of comet Halley by the Halley Multicolour Camera (HMC) on board the European Space Agency's Giotto spacecraft were supported by an extensive ground-based observational programme using the same filter set1. The intention was to place the transitory but detailed observations of the encounter in the frame of ground-based o…
Collisions with cometary dust recorded by the Giotto HMC camera.
Keller, H. U.; Curdt, W.
The authors concentrate on the detailed directional information provided by the Halley Multicolour Camera (HMC) as a result of its excellent resolution and the high attitude stability of the Giotto spacecraft. This information was used to determine the trajectory and to identify attitude excursions caused by discrete dust impacts on the space prob…
Position of comet P/Halley at the Giotto encounter
Wilhelm, K.; Keller, H. U.; Curdt, W. +2 more
Images of the Halley Multicolor Camera (HMC) were analyzed to evaluate the fly-by geometry of the Giotto spacecraft past Comet Halley. The position of the comet at closest approach was determined with respect to the spacecraft. Based on the orbit information of Giotto the absolute position of the cometary nucleus could be obtained with very high p…