PLASMON

The security of space assets are affected by the high-energy charged particle environment in the radiation belts. The controlling principal source and loss mechanisms in the radiation belts are not yet completely understood. During a geomagnetic storm the length of time during which space assets are in danger is determined by the loss mechanisms, particularly by relativistic electron precipitation. The primary mechanism for this precipitation is the interaction of several wave modes with resonant electrons which leads to scattering into the atmospheric loss cone.
The nature of the wave activity and the interactions between the waves and radiation belt particles are strongly governed by the properties of the plasmasphere.

At this point there are few existing and regular measurements of plasmaspheric properties, with existing plasmaspheric models lacking the structures known to exist in the real plasmasphere. There is evidence that enhanced wave activity and enhanced radiation belt losses occur due to such structures. In addition, there are large uncertainties concerning the fundamental nature of relativistic electron precipitation (REP), due to the difficulties of undertaking quality in-situ measurements.
To address these uncertainties in this proposed project we will provide regular longitudinally-resolved measurements plasmaspheric electron and mass densities and hence monitor the changing composition of the plasmasphere, one of the properties which determines wave growth. This will allow us to develop a data assimilative model of the plasmasphere.

At the same time, we will monitor the occurrence and properties of REP, tying the time-resolved loss of relativistic electrons to the dynamic plasmasphere observations.
Our approach will primarily use ground-based networks of observing stations, operating in the ULF and VLF ranges, deployed on a worldwide level. Our proposal is made up of 6 work packages to meet these science goals.