Analysis of the first data collected by the High Accuracy Accelerometer (HAA) onboard the JUICE spacecraft

The JUpiter ICy moons Explorer (JUICE) mission is a cornerstone of the European Space Agency (ESA). The mission was launched in April 2023 from Kourou with an Ariane V launcher and is expected to arrive at Jupiter in 2031. JUICE will investigate the gas giant planet Jupiter, its atmosphere, magnetosphere, and its icy moons, Ganymede, Europa and Callisto. The mission will focus on Ganymede, during the low altitude circular and polar orbital phase.

The spacecraft will carry a suite of scientific instruments, including a camera, a spectrometer, a radar system, a laser altimeter, and a suite of instrumentation dedicated to radio science experiments: the Ka-band Transponder (KaT), the Ultra Stable Oscillator (USO) and the High Accuracy Accelerometer (HAA).

The Gravity & Geophysics of Jupiter and Galilean Moons experiment (3GM) instrumentation will be used to study the gravity field up to degree and order 40 of Ganymede and the extent of internal oceans on the icy moons. Furthermore, during radio occultations, the 3GM experiment will investigate the structure of the neutral atmospheres and ionospheres of Jupiter and its moons.

The HAA accelerometer will play a fundamental role during the 3GM experiment even if it will not directly measure any of the physical quantities connected with the experiment scientific goals. It aims to measure the perturbations of non-gravitational forces that the JUICE spacecraft will undergo during 3GM measurements with an accuracy of  in the frequency band of  Hz. Such perturbations are mainly induced by the propellant sloshing within the tanks, especially during the moon flybys. These perturbing accelerations are included in the orbital determination algorithm. In this work we show the first inflight data collected by the HAA instrument during the cruise. We present the data collected after launch (April-June 2023) during the deployment of the spacecraft moving appendages such as the RIME antenna, the Langmuir probes and the magnetometer boom. The analysis of these data aims to preliminary characterize the instrument behaviour and the spacecraft dynamic environment. Additionally, we show the analysis of the HAA data collected during the first payload checkout (January 2024), with a focus on the preliminary assessment on the instrument in-flight scientific performances.