First results from the Giotto magnetometer experiment at comet Halley
Neubauer, F. M.; Glassmeier, K. H.; Pohl, M.; Ungstrup, E.; Raeder, J.; Burlaga, L. F.; Wallis, M. K.; Ness, N. F.; Musmann, G.; Mariani, F.; Acuna, M. H.; Schmidt, H. U.
Germany, United States
Abstract
The Giotto magnetometer experiment at comet Halley has for the first time provided magnetic field measurements in all the important spatial regions characterizing the front-side interaction between the solar-wind magnetoplasma and a cometary atmosphere. Upstream waves of cometary origin have been observed at distances of >2×106 km from the comet, both inbound and outbound. A cometary bow shock has been identified at 1.15×106 km inbound on the dawn side and a thick quasi-parallel cometary bow shock outbound. A turbulent magnetosheath has been observed further inside. A magnetic pile-up region has been identified inside 1.35×105 km, inbound, and 2.63×105 km, outbound, with fields up to 57 and 65 nT, respectively. A cavity region with essentially zero magnetic field has been discovered, with a width of 8,500 km along the trajectory around closest approach.