3D mapping of the Earth’s trapped radiation particles using μASC: from the inner zone to the magnetosphere

As a pioneer of the fully autonomous star trackers, the micro Advanced Stellar Compass (DTU Space) has been operating successfully on numerous satellite missions ranging from Low Earth Orbiters (e.g. ESA’s Swarm) to Deep Space missions (e.g. NASA’s Juno), accurately providing absolute attitude reference.

Besides its primary function of attitude determination, the μASC is also capable of detecting and monitoring the population of the Earth’s high energy particles. The particles with energies high enough (>20MeV) to pass the heavy shielded optics, will leave a temporary trace on the CCD sensor. The signature of these high energy particles is eliminated in flight by the instrument software ensuring full performance even during the most intense CMEs.

Mapping the rate of the penetrating particles on the CCD sensor enables the monitoring of the high energy particle flux. We present compilation of detected particle flux, its global maps and radial variation from 400 to 10000 km altitude. We further present a view of the dynamic part of the flux, from injection sources such as CMEs, which gives a detailed profiling of the direction, injection time scales and relaxation times.