Galileo IOV - Launch and Early Orbit Phase report

The second launch of Galileo IOV spacecraft (FM3 and FM4) took place at 20:15 CET on Friday, 12 October with spacecraft separation from the launcher and first acquisition of telemetry taking place as planned just after midnight.

The Launch and Early Orbit Phase (LEOP) operations continued until the handover of the spacecraft to the routine operations team at the Galileo Control Centre in Oberpfaffenhofen, Germany. The handovers took place at 08:00 CET on Friday, 19 October (for FM4) and at 20:10 CET on Saturday 20 October (for FM3).

The LEOP operations proceeded according to plan despite the unexpected triggering of Intermediate Safe Mode on both spacecraft after the first transitions to Normal Mode. After recovery and assessments of the possible causes for these unexpected transitions it was decided to modify the spacecraft configurations to avoid further events and to continue with the planned operational sequence. In the meantime the cause of the trigger (a torque due to outgassing is suspected) has diminished to the point where the spacecraft could be returned to their planned configuration.

Three orbit manoeuvres were conducted for each spacecraft to start them on drift orbits towards their operational positions, where they are expected to arrive on 10 (FM3) and 12 November (FM4) after a series of drift stop and fine positioning manoeuvres. The two spacecraft will be configured into the secure mode shortly after hand-over and whilst they are underway to their final position they will undergo a series of tests to confirm the performance of the platform subsystems before switching on the payload after fine positioning is complete.