The Search-Coil Magnetometer (SCM) of the Radio and Plasma Waves Investigation (RPWI) onboard the ESA JUICE mission: in-flight performance and first observations.

The JUpiter ICy moons Explorer (JUICE) mission is the first large-class (L1) mission of ESA Cosmic Vision. JUICE has been launched in April 2023 with an arrival at Jupiter in 2031 and at least four years making detailed plasma observations of Jupiter's magnetosphere and of three of its largest moons (Ganymede, Callisto and Europa). The Radio and Plasma Wave Investigation (RPWI) consortium will carry the most advanced set of electric and magnetic fields sensors ever flown in Jupiter's magnetosphere, which will allow to characterize the radio emission and plasma wave environment of Jupiter and its icy moons. The Search Coil Magnetometer (SCM) of RPWI, combined with the RPWI Low-Frequency receiver (LF), will provide for the first time three-dimensional measurements of magnetic field fluctuations within Jupiter's magnetosphere, with high sensitivity (~10 fT / √Hz at 1 kHz) in the frequency range 0.1 Hz - 20 kHz. Here we present SCM in-flight performance and first observations obtained during its cruise phase, including those from the Lunar-Earth Gravity Assist (LEGA) in 2024. These observations show a nominal functioning and performance of SCM, in agreement with ground calibrations, together with a rather good magnetic cleanliness of the JUICE spacecraft. Observations during LEGA have also allowed to properly identify a number of plasma boundaries in the Earth’s magnetosphere, such as the magnetopause and the magnetotail current sheet, successfully testing the SCM capability to study such boundaries at Jupiter’s and of Ganymede's magnetosphere.