Search Publications
A new look at the nature of comet Halley's LF electromagnetic waves: Giotto observations
Neubauer, Fritz M.; Tsurutani, Bruce T.; Glassmeier, Karl-Heinz +1 more
All of the comet Halley high-time resolution magnetic field data have been examined to determine the nature of the “turbulence” and its difference from that of comets Giacobini-Zinner and Grigg-Skjellerup. Although much of the wave appears unpolarized, occasionally there are intervals of clear order. We find several interesting new wave polarizati…
Pick-up ions and associated wave energy transport at comet P/Halley: A case study
Neubauer, Fritz M.; Glassmeier, Karl-Heinz; Söding, Anne +1 more
During the flyby of the spacecraft Giotto at comet p/Halley Poynting vectors and Elsässer variables have been determined to study wave propagation directions. The observed wave properties are compared with the theoretically predicted RH-, LH+ and LH- wave modes. Between 10:36 and 19:11 SCET on March 13, 1986 the pr…
An intercomparison of plasma turbulence at three comets: Grigg-Skjellerup, Giacobini-Zinner, and Halley
Glassmeier, K. -H.; Neubauer, F. M.; Tsurutani, Bruce T.
We examine and intercompare the LF plasma wave turbulence at three comets: Grigg-Skjellerup (GS), Giacobini-Zinner (GZ), and Halley (H). All three have power spectral peaks at the local ion cyclotron frequency (the pump wave) at ∼10-2 Hz, and a power-law fall-off at higher frequencies that suggest the development of turbulent cascades […
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…
Pickup water group ions at comet Grigg-Skjellerup
Coates, A. J.; Winningham, J. D.; Borg, H. +9 more
The density and velocity distribution of cometary water group ions was measured by the Giotto spacecraft in the regions upstream and downstream of the ‘bow shock’ at comet Grigg-Skjellerup. The results show that the distributions of ions are ring-like until quite close to the shock, the timescales for pitch angle and energy diffusion appear simila…
Predictions of the solar wind interaction with Comet Grigg-Skjellerup
Coates, A. J.; Johnstone, A. D.; Huddleston, D. E.
The planned encounter of the Giotto spacecraft with comet Grigg-Skjellerup on 10th July 1992 promises to extend our knowledge of the solar wind interaction with comets substantially. While there have been spacecraft missions to comets before now, this mission is exploratory in the sense that the target comet is much older and therefore it has a mu…
Gas release from ice/dust mixtures
Krankowsky, D.; Mauersberger, K.; Hesselbarth, P. +4 more
Gas fluxes from insolated ice/dust mixtures were measured by pressure gauges and a mass spectrometer placed one meter in front of the sample. As soon as the insolation of about one solar constant was started a fast rise in H2O and CO2 emissions from the fresh surface was observed. Thereafter gas fluxes slowly decreased. When …
Giotto's Mission to planet Earth
Glassmeier, K. -H.; Neubauer, F. M.; Ungstrup, E. +9 more
After its successful encounter with comet P/Halley and a four-years hibernation period ESA's Giotto spacecraft has been reactivated in February 1990 and performed the first-ever Earth gravity-assisted maneuver on July 2, 1990 to be retargeted for comet P/Grigg-Skjellerup. This swing-by is of unique scientific interest due to Giotto's hyperbolic, h…
Hypervelocity dust particle impacts observed by the Giotto Magnetometer and Plasma Experiments
Coates, A. J.; Glassmeier, K. -H.; Neubauer, F. M. +3 more
We report thirteen very short events in the magnetic field of the inner magnetic pile-up region of comet Halley observed by the Giotto magnetometer experiment together with simultaneous plasma data obtained by the Johnstone plasma analyzer and the ion mass spectrometer experiments. The events are due to dust impacts in the milligram range on the s…
Analysis of suprathermal electron properties at the magnetic pile-up boundary of comet P/Halley
Anderson, K. A.; Neubauer, F. M.; Rème, H. +10 more
Among the plasma discontinuities detected by the GIOTTO spacecraft around comet P/Halley, the Magnetic Pile-up Boundary, located at about 135,000 km from the nucleus, has a sharpness which was not foreseen by theoretical models. At this boundary, which marks the beginning of the region where the field lines draped around the nucleus have been pile…