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Comet P/Halley's nucleus and its activity
Keller, H. U.; Reitsema, H. J.; Delamere, W. A. +2 more
The Halley Multicolour Camera on board ESA's Giotto spacecraft observed the nucleus of comet P/Halley and its environment and returned more than 2000 images. The observations are summarized, their calibration is described, the status of the analysis and the results are discussed. Topographic features on the nuclear surface and areas of activity ar…
To CO and N2 Abundance in Comet p/ Halley
Berthelier, J. J.; Eberhardt, P.; Krankowsky, D. +8 more
A preliminary evaluation of the mass 28 amu/e signal observed in the neutral mode of the Giotto neutral gas mass spectrometer (NMS) is presented. At 1000 km from the nucleus the authors obtain for the CO number density n(CO)/n(H2O) ≤ 0.07. The production rate of CO as parent molecule directly from the nucleus is thus less than 7% of the…
The dust distribution within the inner coma of comet P/Halley 1982i - Encounter by Giotto's impact detectors
Zarnecki, J. C.; Wallis, M. K.; Sekanina, Z. +12 more
Analysis of the data from Giotto's Dust Impact Detection System experiment (DIDSY) is presented. These data represent measurement of the size of dust grains incident on the Giotto dust shield along its trajectory through the coma of comet P/Halley on 1986 March 13/14. First detection occurred at some 287,000 km distance from the nucleus on the inb…
Evidence for methane and ammonia in the coma of comet P/Halley
Ip, W. -H.; Allen, M.; Yung, Y. +2 more
Methane and ammonia abundances in the coma of Halley are derived from Giotto IMS data using an Eulerian model of chemical and physical processes inside the contact surface to simulate Giotto HIS ion mass spectral data for mass-to-charge ratios (m/q) from 15 to 19. The ratio (m/q) = 19/18 as a function of distance from the nucleus is not reproduced…
Expansion Velocity and Temperatures of Gas and Ions Measured in the Coma of Comet p/ Halley
Berthelier, J. J.; Eberhardt, P.; Krankowsky, D. +9 more
In situ measurements of flow velocity and temperature in the inner coma were obtained from ram energy spectra of molecules and ions observed by the NMS experiment onboard the Giotto probe to comet Halley. Radial flow speed was (800 ± 50) m s-1 at distances from the nucleus between 1000km and 4000 km. Whereas ions became stagnant just ou…
Giotto magnetic-field results on the boundaries of the pile-up region and the magnetic cavity
Neubauer, F. M.
Data from Giotto's magnetometer collected during the encounter at Comet Halley on March 13/14, 1986, were used to investigate the most conspicuous boundaries in the inner plasma region surronding Comet Halley, i.e., the pile-up boundary and the ionopause. The normal vectors at the boundary crossings were determined using the minimum variance techn…
Systematics of the CHON and Other Light Element Particle Populations in Comet p/ Halley
Kissel, J.; Clark, B. C.; Mason, L. W.
Based on chemical signatures measured by the PIA experiment during the Giotto flyby of comet P/Halley, a number of particle classifications have been designated. In addition to silicate-like grains and particles of mixed (cosmic) composition, there appear to be several light-element rich populations including the CHON, (H,C), (H, C, O), and (H,C,N…
First statistical analysis of 5000 mass spectra of cometary grains obtained by PUMA 1 (Vega 1) and PIA (Giotto) impact ionization mass spectrometers in the compressed modes
Langevin, Y.; Bertaux, J. -L.; Kissel, J. +1 more
Impact ionization mass spectrometers have been flown on board the space vehicles Giotto (instrument PIA), Vega 1 and Vega 2 (instruments PUMA 1 and 2). All three instruments obtained a large collection of mass spectra of individual cometary dust particles in the mass range 3×10-16 - 3×10-10g. Spectra from PUMA 2 are still bei…
The D/h Ratio in Water from Comet p/ Halley
Berthelier, J. J.; Eberhardt, P.; Krankowsky, D. +6 more
The neutral gas mass spectrometer on the Giotto spacecraft made neutral and ion composition measurements with a high mass resolution. From a preliminary evaluation of the ion data within the contact surface the authors obtain for the water in Halley an 18O abundance of 18O/16O = 0.0023±0.0006 and for the D/H ratio …
General Features of Comet p/ Halley - Solar Wind Interaction from Plasma Measurements
Anderson, K. A.; Reme, H.; Korth, A. +8 more
The Giotto RPA-COPERNIC plasma experiment identified several regions in which the solar wind interaction with the cometary plasma displayed characteristic features: (1) Beginning ∼4.6×106km from the comet there is an upstream region with sporadic connection to the comet, (2) An electron foreshock is present up to 2.5×105km aw…