THE ELECTROMAGNETIC EFFECTS OF THE SOLAR-WIND INTERACTION WITH PHOBOS

The electromagnetic effects of the solar wind interaction with the neutral gas halo and dust ring around Phobos are examined. The analysis is used to account for the strong correlation which arises during the Phobos mission between the local enhancement of the electron density and magnetic fluctuations and the spacecraft crossings with the Phobos orbit. The neutral gas interaction cannot account for the correlation since the outgassing rate of Phobos is too low. For the dust ring interaction however, a local enhancement of the electron density is expected in regions which are dominated by positively charged dust grains and magnetic disturbances will arise. The electrons are decoupled from the solar wind protons and evidence of this is seen from the high level of wave activity at frequencies below 100 Hz.