Details

Autor(en) / Beteiligte

• Sanchez-Torres, A.
• Sanmartin, J. R.

Titel

Tether radiation in Juno-type and circular-equatorial Jovian orbits

Ist Teil von

• Journal of Geophysical Research: Space Physics, 2011-12, Vol.116 (A12), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2011

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Wave radiation by a conductor carrying a steady current in both a polar, highly eccentric, low perijove orbit, as in NASA's planned Juno mission, and an equatorial low Jovian orbit (LJO) mission below the intense radiation belts, is considered. Both missions will need electric power generation for scientific instruments and communication systems. Tethers generate power more efficiently than solar panels or radioisotope power systems (RPS). The radiation impedance is required to determine the current in the overall tether circuit. In a cold plasma model, radiation occurs mainly in the Alfvén and fast magnetosonic modes, exhibiting a large refraction index. The radiation impedance of insulated tethers is determined for both modes and either mission. Unlike the Earth ionospheric case, the low‐density, highly magnetized Jovian plasma makes the electron gyrofrequency much larger than the plasma frequency; this substantially modifies the power spectrum for either mode by increasing the Alfvén velocity. Finally, an estimation of the radiation impedance of bare tethers is considered. In LJO, a spacecraft orbiting in a slow downward spiral under the radiation belts would allow determining magnetic field structure and atmospheric composition for understanding the formation, evolution, and structure of Jupiter. Additionally, if the cathodic contactor is switched off, a tether floats electrically, allowing e‐beam emission that generate auroras. On/off switching produces bias/current pulses and signal emission, which might be used for Jovian plasma diagnostics. Key Points The voltage drop for FM emission in Jupiter is 30‐100 times greater than in LEO Alfvén impedance in Jupiter is several orders of magnitude greater than in LEO Impedance of Jovian tethers is reduced by about half if stripped of insulation