ORBIT DETERMINATION PERFORMANCE OF THE GANYMEDE FLYBYS BY THE JUNO SPACECRAFT

On June 7, 2021 the Juno spacecraft zoomed past Ganymede at an altitude of ∼1,050 km, the first of four targeted “close” flybys of a Galilean moon along the newly accepted extended mission (EM) reference trajectory. While monitoring the real-time Doppler residuals during the flyby, the orbit determination (OD) team was surprised to see an anomalous signature in the data surrounding the time of closest approach. This paper will detail the OD team’s preparation for the flyby, a first-time event for the Juno mission, and the subsequent analyses to understand the anomaly. We will also investigate the flyby performance of the subsequent untargeted distant Ganymede flyby on July 20, 2021.