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The extended formaldehyde source in comet P/Halley
Eberhardt, P.; Meier, R.; Krankowsky, D. +1 more
The Neutral Mass Spectrometer on the Giotto spacecraft measured the neutral and ion composition in the coma of comet P/Halley. In the ion mass spectra, the 31 amu/e peak is dominated by the protonated formaldehyde ion H3CO+ and can be used to calculate the H2CO density. The radial profile of the amplitude of the 31…
First results from the Giotto magnetometer experiment during the P/Grigg-Skjellerup encounter
Glassmeier, K. -H.; Neubauer, F. M.; Pohl, M. +9 more
The Giotto magnetic field experiment has provided the first magnetic field data on the interaction between the solar wind and a low gas production comet, P/Grigg-Skjellerup. Waves produced by ion pick-up instabilities have been observed throughout the interaction region with particularly simple waveforms at large distances and a rich phenomenology…
Observations of the Solar Wind and Cometary Ions during the Encounter Between Giotto and Comet Grigg-Skjellerup
Coates, A. J.; Winningham, J. D.; Borg, H. +6 more
The solar wind interaction with the outfiowing gas from a second comet has been recorded by the same in-situ instrumentation that was used for the comet Halley encounter m 1986. The new comet, Grigg-Skjellerup, is the smallest so far observed since the size of the interaction region is comparable with a cometary ion gyroradius Preliminary results …
The ion population between 1300 KM and 230000 KM in the coma of comet P/Halley
Altwegg, K.; Balsiger, H.; Geiss, J. +6 more
During the encounter of the spacecraft Giotto with Comet Halley the two sensors of the ion mass spectrometer (IMS), high energy range spectrometer (HERS) and high intensity spectrometer (HIS), measured the mass and the three-dimensional velocity distributions of cometary ions. HIS looked mainly at the cold, slow part of the distribution close to t…
Dust particle impacts during the Giotto encounter with comet Grigg-Skjellerup
Colangeli, L.; Green, S. F.; Greenberg, J. M. +7 more
IN the European Space Agency's 1992 Giotto Extended Mission, the Dust Impact Detection System operated successfully during a fly-by that took the spacecraft within about 200 km of the nucleus of comet Grigg-Skjellerup. During the encounter, three meteoroid impacts were detected on Giotto's front shield. The particle masses were found to be lOO
Low-frequency electromagnetic plasma waves at comet P/Grigg-Skjellerup: Overview and spectral characteristics
Neubauer, Fritz M.; Glassmeier, Karl-Heinz
Large-amplitude electromagnetic plasma waves are one of the dominant features of the solar wind-comet interaction. Wave characteristics strongly depend on parameters such as the solar wind flow and Alfvén velocities and the angle between flow and interplanetary magnetic field as well as the production rate. With respect to the latter the flyby of …
Mirror modes and fast magnetoacoustic waves near the magnetic pileup boundary of comet P/Halley
Motschmann, Uwe; Neubauer, Fritz M.; Fuselier, S. A. +4 more
Large-amplitude ultralow-frequency wave structures observed on both sides of the magnetic pileup boundary of comet P/Halley during the flyby of the Giotto spacecraft have been analyzed using suprathermal electron density and magnetic field observations. Upstream of the boundary, electron density and magnetic field magnitude variations are anticorr…
Velocity space diffusion and nongyrotropy of pickup water group ions at comet Grigg-Skjellerup
Coates, A. J.; Neubauer, Fritz M.; Wilken, B. +1 more
The diffusion of water group cometary ions in velocity space at comet Grigg-Skjellerup was measured during the Giotto spacecraft encounter. The evolution of the collapsed pitch angle and energy distributions during the inbound and outbound passes shows that the timescale for energy diffusion may be similar to that for pitch angle diffusion. Fully …
Discrete wave packets at the proton cyclotron frequency at comet P/Halley
Neubauer, F. M.; Mazelle, C.
We present in this letter the first experimental evidence for wave packets near the local proton cyclotron frequency in the plasma environment of a comet. The observations have been made by the GIOTTO magnetometer experiment (MAG) around comet P/Halley on both sides of closest approach. The waves are always left-handed in the spacecraft frame, ell…
Low-frequency electromagnetic plasma waves at comet P/Grigg-Skjellerup analysis and interpretation
Coates, A. J.; Neubauer, Fritz M.; Glassmeier, Karl-Heinz +1 more
The propagation and polarization characteristics of low-frequency electromagnetic wave fields near comet P/Grigg-Skjellerup (P/GS) are analyzed using magnetic field and plasma observations obtained by the Giotto magnetometer experiment and the Johnstone plasma analyzer during the encounter at the comet on July 10, 1992. The results have been physi…