Search Publications
Giotto's second encounter: The mission to comet P/Grigg-Skjellerup
Schwehm, G.; Grensemann, M. G.
The second highlight in the life of the Giotto spacecraft, which was originally designed for a short 8-month lifetime, occurred on 10 July 1992. The main mission was to explore and photograph Halley's Comet; however, not only did Giotto survive the harsh environment around the comet Halley but is was also able, after more than 7 years in orbit aro…
Ulysses measurements of energetic H3 molecules in Jupiter's magnetosphere
Lanzerotti, L. J.; Maclennan, C. G.; Feldman, D. M.
The Voyager 2 measurements of energetic (~1 MeV/nucleon) H3 molecules in Jupiter's magnetosphere provided strong evidence that the planet's ionosphere is an important plasma source in the Jovian environment (Hamilton et al., 1980). During the Ulysses spacecraft encounter with Jupiter in February 1992 the Heliosphere Instrument for Spect…
Measurement of direct current electric fields and plasma flow speeds in Jupiter's magnetosphere
Balogh, A.; Goetz, K.; Forsyth, R. J. +3 more
During the encounter of Ulysses with Jupiter, we have measured two components of the dc electric field and deduced from them the flow speed in the Io torus, as well as the presence of a polar cap region and what we interpret as a cleft region. Within the torus the flow speed is approximately equal to the speed of a plasma corotating with Jupiter b…
On the momentum balance along the comet Halley-Sun line during the Giotto flyby
Neubauer, F. M.; Israelevich, P. L.; Ershkovich, A. I.
The plasma velocity along the Sun-comet Halley line is derived by using in situ measurements of the magnetic field along the Giotto trajectory. Including this velocity profile in the momentum balance turns out to be insufficient in order to support the magnetic barrier with conventional parameters of ion-neutral interaction. The observed magnetic …
Upper limits to Jovian hard X radiation from the Ulysses gamma ray burst experiment
Hurley, K.; Sommer, M.; Waite, J. H.
We describe the first in situ search for Jovian X radiation with a dedicated X ray instrument. Upper limits to Jupiter's X ray power in the 27-48 keV range are presented using data taken by the gamma ray burst experiment on the inbound Ulysses trajectory, at distances between 163 and 110 RJ. The data were analyzed using three methods fo…
Possible in situ detection of K2+ in the Jovian magnetosphere
McNutt, Ralph L., Jr.
During the Voyager 1 and 2 encounters with Jupiter in 1979 the positive ion composition of the cold thermal plasma in the Jovian plasma sheet and cold Io torus could be obtained when the plasma Mach number in the spacecraft rest frame was sufficiently large. Clear indication of an ionic species with a mass-to-charge ratio between 16 (O+…
Relationship between wave energy and free energy from pickup ions in the Comet Halley Environment
Johnstone, A. D.; Huddleston, D. E.
The free energy available from the implanted heavy ion population at comet Halley is calculated by assuming that the initial unstable velocity space ring distribution of the ions evolves toward a bispherical shell. Ultimately this free energy adds to the turbulence in the solar wind. We obtain upstream and downstream free energies separately for t…
Quasi-linear velocity space diffusion of heavy cometary pickup ions on bispherical diffusion characteristics
Coates, A. J.; Johnstone, A. D.; Huddleston, D. E.
We consider an ion transport equation describing the source, convection, adiabatic acceleration, and quasi-linear velocity diffusion of cometary pickup ions. The equation is solved numerically along solar wind plasma flow lines for the environment of comet Halley, to obtain distributions at positions on the Giotto spacecraft trajectory which may b…
Observations of Plasma Dynamics in the Coma of P/Halley by the Giotto Ion Mass Spectrometer
Schwenn, R.; Balsiger, H.; Ip, W. -H. +7 more
Observations in the coma of P/Halley by the Giotto ion mass spectrometer (IMS) are reported. The high-energy range spectrometer (HERS) of the IMS obtained measurements of protons and alpha particles from the far upstream region to the near ionopause region and of ions of mass 12-32 at distances of about 250,000 to 40,000 km from the nucleus. Plasm…
Properties of mass-loading shocks 2. Magnetohydrodynamics
Neubauer, F. M.; Zank, G. P.; Oughton, S. +1 more
The one-dimensional magnetohydrodynamics of shocked flows subjected to significant mass loading are considered. Recent observations at comets Giacobini-Zinner and Halley suggest that simple nonreacting MHD is an inappropriate description for active cometary bow shocks. The thickness of the observed cometary shock implies that mass loading represen…