[PPS01-P10] Magnetic field experiment at Jupiter icy moons (JUICE J-MAG) and in-flight alignment calibration
Keywords:Jupiter, Jovian moons, magnetometer
J-MAG science requirements result in a requirement on the spacecraft to determine accurate knowledge of the orientation of the fluxgate sensors (MAGIBS and MAGOB). Due to the long MAG boom it is not possible to meet J-MAG’s alignment requirement by mechanical stability alone, therefore the spacecraft includes two orthogonal coils mounted around its body. The coils can be driven with a current which produces a measurable magnetic field vector at the fluxgate sensors. This signal can then be used by the fluxgates to track the variation in the sensor alignment. This technical note describes the results of an analysis using an alignment recovery technique that was developed for the Kaguya mission, applied to the specific case of JUICE, considering the relative positions of the fluxgate sensors with respect to the JACS coils.
We derived equations to calculate the directions of the measurement axes in the frame fixed to the spacecraft, namely alignment angles, from the measurement results of reference magnetic fields generated by JACS. The errors of the alignment angle estimation and their dependence on measurement noise as well as inaccuracy of the coil current intensity are examined. Based on the quantitative results, the requirements to the JACS design and operation to satisfy the requests to the alignment accuracy are determined.