The latest addition to Galileo’s worldwide ground infrastructure has been made in the mid-Atlantic, on Portugal’s Santa Maria island in the Azores. This new Galileo Sensor Station joins a far-flung network of stations monitoring signal quality, clock timings and positioning of the Galileo satellites orbiting Earth.
Its formal opening ceremony on March 26 was presided over by the Azores’ Regional Secretary of Tourism and Transport Vitor Fraga and ESA’s Galileo Ground Segment Procurement Manager Syvain Loddo.
The station’s omnidirectional antenna itself is just half a meter in length, but also requires a power plant and guard house as well as a pair of small VSAT satellite antennas to link the station to the worldwide Galileo Ground Segment.
About 1500 km from mainland Portugal, the small, mountainous island of Santa Maria is already home to an ESA Estrack station, used to follow launches from Europe’s Spaceport in Kourou, French Guiana. The new station is adjacent to this existing site, known locally as the Montes das Flores (Hill of Flowers). It is built on land owned by the Region of Azores, which is Portugal’s public regional authority overseeing the archipelago. The site meets Galileo’s characteristic needs, located away from built-up areas on flat land offering a clear view of the sky in all directions.
Both stations have been built by Portugal’s Edisoft company, part of the Thales Group, also responsible for maintaining and running the sites.
Later this year, the Azores station will also host a reference beacon used for assessing Galileo’s Search and Rescue system. As part of the international Cospas–Sarsat system, the medium-orbit Galileo constellation is equipped to pick up UHF signals from emergency beacons aboard ships, aircraft or carried by individuals for relay to the nearest emergency services.
The island has a notable footnote in the history of navigation: reputedly, Christopher Columbus’s flagship Niña landed there in February 1493, having just “discovered” the Americas.
Santa Maria’s climate is mild, although identical Galileo stations have been established everywhere from stormy Arctic islands to the icebound Antarctic mainland.
Multiple Galileo Sensor Station sites will work together to perform ranging measurements while holding a Galileo satellite in common view, seeking to identify any orbital drift that might reduce satnav accuracy. This is effectively a reversal of the way satellite navigation normally operates, with multiple satellites’ signals used to pinpoint the user’s receiver location.
Galileo’s ground segment also includes a number of larger Uplink Stations to transmit navigation messages, including any corrections for rebroadcast to users, as well as Telemetry, Tracking and Command Stations to oversee the satellite platform. A pair of control centres in Fucino, Italy, and Oberpfaffenhofen, Germany, oversees the satellites and their navigation services.
The first four Galileo satellites are already in orbit and operational. Over the course of 2014 more satellites will join them, with initial Galileo services scheduled to start by the end of this year.