ESA Science & Technology - Publication Archive
These outflowing beams were generally detected below 100 eV and typically between 40 and 70 eV, just above the photoelectron level. Their energy gain can be explained by the presence of a field-aligned potential drop below the spacecraft, as in the auroral zone. The careful analysis of the beams distribution function indicates that they were not only accelerated but also heated. The parallel heating is estimated to about 2 to 20 eV and it globally tends to increase with the acceleration energy. Moreover, WHISPER observed broadband electrostatic emissions around a few kHz correlated with the outflowing electron beams, which suggests beam-plasma interactions capable of triggering plasma instabilities.
In presence of simultaneous very weak ion fluxes, the outflowing electron beams are the main carriers of downward field-aligned currents estimated to about 10 nA/m². These electron beams are actually not isolated but surrounded by wider structures of ion outflows. All along its polar cap crossings, Cluster observed successive electron and ion outflows. This implies that the polar ionosphere represents a significant source of cold plasma for the magnetosphere during northward or weak IMF conditions. The successive ion and electron outflows finally result in a filamented current system of opposite polarities which connects the polar ionosphere to distant regions of the magnetosphere.
This document has been prepared to give a concise overview of the studies that have been performed in the framework of the Jovian related Technology Reference Studies. The goal of these studies is the identification of technologies that are required to enable possible low resource missions to the Jovian System. These activities are subdivided in three main topics:
- The Jovian Minisat Explorer (JME): The exploration of Europa and the Jovian System
- The Jupiter Entry Probe (JEP): In situ exploration of the Jovian atmosphere up to 100 bar
- The Jovian System Explorer (JSE): Study of the Jovian magnetosphere and the Jovian System