Latest Galileo satellites join constellation with enhanced, faster fix

Galileo launch 11 from Europe’s spaceport in French Guyana sent satellites 27 and 28 into orbit. (Photo: ESA/CNES/Arianespace)

News from the European Space Agency (ESA)

Europe’s latest Galileo satellites in space have joined the operational constellation, transmitting navigation signals to three billion users across Earth as well as relaying distress calls to rescuers.

Their entry into service follows a summer test campaign and will result in a measurable increase in positioning accuracy and improved data delivery performance of the overall Galileo system.

Galileo satellites 27-28 were launched at the end of 2021 and underwent in-orbit test review at the end of April. The review was conducted by ESA, satellite manufacturer OHB, and navigation payload maker Surrey Satellite Technology Ltd (SSTL).

Key findings showed both satellites’ payloads are performing extremely well — among the best in the entire constellation — and the satellites entering into service increase the position accuracy and robustness of the overall Galileo system.

A successful system and in-orbit operations review followed, co-chaired by ESA and the EU Agency for the Space Programme (EUSPA), which is in overall charge of commissioning.

Improved navigation message

The two satellites are the first to broadcast an improved navigation message, resulting in three key improvements for Galileo’s public Open Service users:

• faster navigation data acquisition, allowing users to establish a first position fix more rapidly
• better robustness in challenging environments, such as urban centers
• easier access to timing information in the navigation message for users possessing only a rough estimate of timing of the order of 1-2 seconds.

For the testing and broadcasting of this new navigation message, new software for the Navigation Signal Generation Unit was developed by Thales Alenia Space in Italy, SSTL, OHB and ESA, and was uploaded to the two satellites.

During the summer, an extensive test campaign was conducted by ESA to ensure the compatibility of the entire Galileo system at unit, payload, satellite, ground and system levels with the enhanced message. As part of this effort, EUSPA oversaw receiver testing to ensure this compatibility extended to Galileo receivers and chipsets in the market.

These latest launched satellites made ideal test cases for the software and the improved navigation message. Transmission of the upgraded signals from Galileo satellites 27-28 allowed the team to confirm its correct implementation and characterize its long-term performance.

Following a successful Test Review Board, the satellites were brought back into service on Aug. 29