ESA - GALILEO Programme logo.
8 June 2017
Two further satellites have formally become part of Europe’s Galileo satnav system, broadcasting timing and navigation signals worldwide while also picking up distress calls across the planet.
Galileo satellite in orbit
These are the 15th and 16th satellites to join the network, two of the four Galileos that were launched together by Ariane 5 on 17 November, and the first additions to the working constellation since the start of Galileo Initial Services on 15 December.
The growing number of Galileo users around the world will draw immediate benefit from the enhanced service availability and accuracy brought by these extra satellites.
The launch into space and the manoeuvres to reach their final orbits still left a lot of rigorous testing before the satellites could join the operational constellation.
Liftoff of Galileo quartet
Their navigation and search and rescue payloads had to be switched on, checked and the performance of the different Galileo signals assessed methodically in relation to the rest of the worldwide system.
This lengthy testing saw the satellites being run from the second Galileo Control Centre in Oberpfaffenhofen, Germany, while their signals were assessed from ESA’s Redu centre in Belgium, with its specialised antennas.
The tests 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.
Surveying with satnav
Oberpfaffenhofen and Redu were linked for the entire campaign, allowing the team to compare Galileo signals with satellite telemetry in near-real time.
Making the tests even more complicated, the satellites were visible for only three to nine hours a day from each site.
Galileo's Redu antenna
The satellites are now broadcasting working navigation signals and are ready to relay any Cospas–Sarsat distress calls to regional emergency services.
Now that these two satellites are part of the constellation, the remaining pair from the Ariane 5 launch is similarly being checked to prepare them for service.
Related links:
Cospas–Sarsat distress calls: http://www.esa.int/Our_Activities/Navigation/Galileo_s_search_and_rescue_service_in_the_spotlight
Launching Galileo website: http://www.esa.int/Our_Activities/Navigation/The_future_-_Galileo/Launching_Galileo
Galileo Tour: http://esamultimedia.esa.int/multimedia/Galileo_tour/galileo.swf?lang=gb&mylang=gb
EC Galileo website: http://ec.europa.eu/growth/sectors/space/galileo/index_en.htm
European GNSS Agency: http://www.gsa.europa.eu/
Galileo begins serving the globe: http://www.esa.int/Our_Activities/Navigation/Galileo_begins_serving_the_globe
Galileo Initial Services: first quarter service performance for users: http://www.esa.int/Our_Activities/Navigation/Galileo_Initial_Services_first_quarter_service_performance_for_users
Images, Text, Credits: ESA/P. Carril/S. Corvaja/CC BY-SA 3.0 IGO.
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