ASPOC, active spacecraft potential control experiment

The spacecraft potential of Double Star TC-1 is positive in large parts of the orbits due to the photo-effect from solar EUV irradiation. These positive potentials typically disturb low energy plasma measurements on board. The potential can be reduced, and thereby the particle measurements improved, by emitting a positive ion beam. This method has successfully been applied on several other spacecraft and it has also been chosen for TC-1. The instrument TC-1/ASPOC is a derivative of the Cluster/ASPOC instruments, from which it has inherited many features. The instrument performs very well and can support higher beam currents than on Cluster. The expected significant improvement of the low energy particle measurements on board was indeed observed. All ASPOC datasets are available on the ESA Cluster Science Archive at https://csa.esac.esa.int/ ASPOC key scientific datasets for TC-1 Dataset ID Dataset content D1_PP_ASP Emitted current, spin resolution D1_SP_ASP Emitted current, 1 minute average