TAMPA, Fla. — Inmarsat said June 8 it has started beaming a test navigation signal from an aging satellite to help the United Kingdom replace space-based capabilities it lost following Brexit.

The British satellite operator is leading a group of local companies that are developing an alternative to the European Geostationary Navigation Overlay Service (EGNOS), which Europe uses to augment and improve GPS services in the region.

The U.K. lost access to EGNOS satellites and ground stations last summer as a result of the country’s 2016 vote to leave the European Union.

This includes access to the EGNOS Safety-of-Life (SoL) service that enables aircraft to make high-precision landing approaches with fewer costly ground-based navigation aids.

The U.K.’s departure from the EU also means the country is no longer involved in Galileo, Europe’s global satellite navigation system (GNSS) that is set to reach full operational capability this year.

The British government has said it is looking to develop a variety of independent space-based capabilities in the wake of Brexit, which also aligns with its strategy to expand the country’s domestic space industry.

According to Inmarsat, it has repurposed a transponder on its I-3 F5 satellite to broadcast a positioning, navigation and timing (PNT) signal that provides a test bed for replacing EGNOS SoL services.

The operator said the signal will help British companies and regulators validate plans for a sovereign UK Space-Based Augmentation System (UKSBAS) to supplement GPS.

The plan is for UKSBAS to use an overlay signal to improve services for satellite navigation users in U.K. airspace and waters, increasing positioning accuracy to a few centimeters compared with the few meters provided by standard GPS alone.

Although I-3 F5 was launched in 1998 to provide connectivity over the U.K. and the Atlantic Ocean, Inmarsat spokesperson Matthew Knowles said it is expected to have enough fuel to continue operating even after the first phase of the UKSBAS tests are due to wrap up in July.

Goonhilly Earth Station is providing the signal uplink for the tests from Cornwall in the southwest of England. GMV NSL, the U.K.-based satellite navigation specialist owned by Spanish technology provider GMV, is generating navigational data from the signal.

Knowles said the companies were awarded about $1.5 million last year from the UK Space Agency, via the European Space Agency’s Navigation Innovation and Support Programme (NAVISP), to conduct the first phase of the tests.

He said further testing phases are set to take place through mid-2024 before UKSBAS can become operational.

In 2017, Inmarsat started conducting tests for a similar augmentation network from another satellite in its fleet for Australia and New Zealand, which are in the middle of procuring an operational system through an open government tender.

Knowles said their program is “expected to begin perhaps later this year or early next year.”

Navigational independence

The British government had initially embarked on plans to develop its own GNSS following Brexit.

However, the government effectively decided not to pursue a full-fledged satellite navigation constellation in September 2020, when it replaced the GNSS project with its Space-Based Positioning Navigation and Timing Programme (SBPP).

Inmarsat was one of six companies in May that won UK Space Agency awards under SBPP — worth more than two million British pounds in total — to study technical and cost issues associated with satellite navigation systems.

UK Space Agency spokesperson Gareth Bethell said these companies have since reported their findings to the government, which is considering them and “is working on next steps.”

Knowles said the UKSBAS project “will help build up skills and capability in the industry” should the government decide to pursue independent satellite navigational capabilities. 

British megaconstellation startup OneWeb, which is partly owned by the British government, is also considering adding PNT to services to its current and next-generation satellites.

Startups including California-based Xona Space Systems, which recently deployed a test satellite, are also developing plans for constellations that could supplement or replace existing GNSS capabilities.

Jason Rainbow writes about satellite telecom, space finance and commercial markets for SpaceNews. He has spent more than a decade covering the global space industry as a business journalist. Previously, he was Group Editor-in-Chief for Finance Information...