8 Dic 2016 Galileo satellites 13 and 14 have begun transmitting navigation signals as fully operational members of Europe’s satnav constellation. The two were launched together from Europe’s Spaceport in French Guiana on 24 May. Their flight into space, and subsequent manoeuvres to reach their final orbital altitude, was only the start of their quest to join the operational constellation. Next, their navigation and search and rescue payloads were methodically switched on, checked out and their performance assessed in relation to the rest of the worldwide Galileo system.
This lengthy test phase saw the satellites being run from the second Galileo Control Centre in Oberpfaffenhofen, Germany, while their payloads’ output was assessed from ESA’s Redu centre in Belgium, equipped for the tests with specialised antennas for receiving and uplinking signals. The test campaign measured the accuracy and stability of the satellites’ atomic clocks – essential for the timing precision to within a billionth of a second as the basis of satellite navigation – as well as assessing the quality of the navigation signals. Oberpfaffenhofen and Redu were linked for the entire campaign, allowing the team to compare Galileo signals with satellite telemetry in near-real time.
These two satellites were visible in the sky above Redu for a limited time each day, ranging from three to nine hours, so tests were scheduled accordingly. Now that in-orbit testing is completed, the satellites are transmitting working navigation signals and are ready to relay any Cospas-Sarsat distress calls to emergency services. The next four satellites, launched together on 17 November, are beginning the same in-orbit testing activity, with the aim of joining the network next spring.