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Interpretation of the measurements of secondary electron currents induced by impacts during the flyby of comet Halley |
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| Authors: | R Grard |
| Institution: | * Space Science Department of ESA, ESTEC, Keplerlaan, 2200 AG, Noordwijk, The Netherlands ** Central Research Institute for Physics, PO Box 49, H-1525, Budapest 114, Hungary *** Space Research Institute, Profsoyuznaya 84/32, 117810, Moscow GSP-7, USSR † Max-Planck-Institut für Kernphysik, Postfach, 103980, D-6900, Heidelberg, FRG ‡ Unit for Space Sciences, University of Kent at Canterbury, Canterbury CT2 7NR, UK § PTS, Leinerweberstr. 60, D-7800, Freiburg, FRG |
| Abstract: | The Giotto, Vega-1 and Vega-2 spacecraft flew through the environment of comet Halley at a relatively close range with velocities of the order of 70–80 km/s. The fore sections of their surface were bombarded by neutral molecules and dust grains which caused the emission of secondary electrons and sputtered ions. This paper makes use of the secondary electron current measurements performed on Vega-1 to infer some characteristic features of the cometary atmosphere. The total gas production rate is estimated to be of the order of 1030 molecules/s and is found to vary with time; the presence of a major jet is also detected at closest approach. |
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