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UK GNSS Solution after Brexit

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In 2018, when the UK's post-Brexit involvement in Galileo was still a point of contention between London and Brussels, UK ministers set aside £92m to study the feasibility of building a sovereign satellite-navigation system. Almost immediately, the UK Space-Based Positioning Navigation and Timing Program (SBPP) became something of a political football, or soccer ball if you prefer. Critics and supporters chimed in vehemently at any piece of news. Why an independent UK PNT system might be necessary remains a reasonable first question for some observers. 1)

The Royal Institute of Navigation has long advocated a balanced and cooperative approach to global PNT, and specifically for not becoming overly reliant on GNSS. The Institute's Director, John Pottle, told Inside GNSS, "For most applications, the open services are all that is needed, and there are already plenty of ranging sources available from the existing GNSSs."

Of course, GPS, Galileo, GLONASS and BeiDou open signals remain freely accessible to all UK-based users, as does EGNOS, the EU's regional augmentation system.

"My understanding," Pottle continued, " is that the UK's current use of encrypted GPS for military purposes is not impacted by Brexit. So in many ways there is not a ‘problem to solve' in the immediate future in relation to provision of services. The question of whether the UK needs control over its own space-based positioning, navigation or timing assets is very much a strategic and political one that I am happy to leave to the politicians to decide!"

The UK Space Agency (UKSA) has its mandate, political or not, and is working to fulfill it. We spoke to UKSA Deputy CEO Ian Annett, who laid out the whys and wherefores. "In line with other nations with significant GDP (GNSS Data Preprocessor)," he said, "we recognize the dependence that we place on space-based PNT. The loss of PNT alone could have up to a billion pounds a day impact on the economy, so we recognize its value in economic terms, but also of course the support that it provides to critical national infrastructure (CNI), whether it's energy, whether it's maritime, whether it's aviation, and therefore it's really a case of how much risk one wishes to take in relying on open signals from other nations."

Annett said that there is no reason to believe the US would ever deny the UK access to the GPS signal. However, he said, "If third party actors would try and jam GPS or remove that signal by whichever means, then having our own assured access to a PNT signal will mean that we could protect that critical national infrastructure, protect our society and protect our economy within the UK."

One is reminded of the initial debate surrounding the nascent Galileo program, when proponents argued that Europe needed an autonomous PNT capability, so as never again to be wholly dependent on the American GPS system, which, after all, could be switched off at a moment's notice by the Pentagon. The UK would seem now to be seeking its own measure of independence and autonomy. The Pentagon has yet to switch off GPS, but the EU has its Galileo nonetheless, and no one blames her. Who then can blame the UK? So the argument might go.

System of Systems

When it comes to technologies, Annett said, it's not a binary choice. It's not a space-based PNT system or a terrestrial system or an RF system. "A first step for us is to understand the complex operating environment within which this system would have to exist. We've got to determine a balance across all of those different technologies that will help preserve that infrastructure, help preserve the economy."

Ninety-five percent of all goods delivered to the UK come by sea. "The maritime sector is entirely dependent on the space-based PNT," Annett said, "because you can't pick up a terrestrial signal in the middle of the Pacific. Clearly there are other systems and technologies that are starting to emerge, whether it be quantum based, that will help things like inertial navigation, but are not quite there yet. So we need to understand where space can protect our economy now."

Here the Agency's approach would seem to align with that of the Royal Institute of Navigation, which is always a good thing. John Pottle said, "I see the way forward as adopting more of a systems engineering approach to PNT design, layering system elements and technologies to deliver the required performance and resilience. Good examples used widely today are GPS plus inertial; or GNSS plus Wi-Fi positioning plus cellular positioning. There is a lot of innovation in non-space-based positioning, navigation and timing systems at present, which show great promise. While space-based PNT will continue to be a very important element, I believe that in future we will see much more in the way of combining complimentary technology elements intelligently."

Earlier this year, the UK government partnered with Indian firm Bharti Global to acquire out of bankruptcy the company OneWeb, with its low-Earth orbit (LEO) broadband megaconstellation. UK Business Secretary Alok Sharma has been cited in the media as saying, "Through our Space-Based Positioning Navigation and Timing Program, we will draw on the strengths of the UK's already thriving space industry to understand our requirements for a robust and secure satellite navigation system. This includes considering low-orbiting satellites that could deliver considerable benefits to people and businesses right across the UK, while potentially reducing our dependency on foreign satellite systems."

As soon as the government associated OneWeb with its plan for a satnav system, observers pointed out that using OneWeb satellites for PNT purposes would be anything but straightforward. For example, see "OneWeb LEO PNT: Progress or Risky Gamble?" in the Sept/Oct issue of this magazine.

John Pottle said, "There are very few, if any, examples where a satellite system designed and optimized for one purpose is perfect for another. In addition, very precise orbit and clock requirements make positioning and timing a challenge for any satellite system."

Alec James, UKSA Comms and Stakeholder Engagement, Space Based PNT Programme, told us, "We've always been clear that a PNT service wasn't the rationale for the investment in OneWeb, which represents a cutting-edge telecommunications capability. That said, it is possible that the system or its future iterations could provide some additional benefits as part of a ‘system of systems' approach to PNT delivery. In particular it could present additional resilience due to its very different broadcast frequency to that of GPS and Galileo."

Widening the Scope

Back in 2018, when the UK first announced its interest in a sovereign satellite-navigation system, many observers understood this to mean a very Galileo-like, medium earth orbit (MEO) GNSS, and subsequent arguments and objections seemed to take that kind of purely space-based system as a baseline. More recently, in a September 2020 statement, the British government's Department for Business, Energy and Industrial Strategy (BEIS), to which UKSA is attached, made explicit a broader approach. The statement said the Agency will look at "new and alternative ways" of providing PNT services. The SBPP would "consider newer, more innovative ideas of delivering global ‘sat nav' and secure satellite services to meet public, government and industry needs." Some observers suggested this new focus meant the UK was throwing in the towel, ready to give up on developing its own a Galileo-like system.

"Have we run out of ideas and are now asking everybody else?" said Annett. "I think the approach that we're taking is really refreshing. It defines a new way of working with industry. It's not about government strapping down a bunch of requirements and then pushing it out to industry and say go away and come back with potential contracts to meet those requirements. This is about engaging with industry.

"The opposite end of the spectrum to that is of course people would accuse us of being arrogant if we thought that we had the answers and all the solutions. There are some very good ideas out there, which can extend from provision of a service-based solution, which we would regulate, all the way into government-owned and government-built. I don't vouch to have all of the answers within the program, so we have gone out to industry and said, hey how would you guys address these problems."

Annett said the Agency will start with a broad list of options, then narrow down and move to the cost-benefits analyses. "Amongst all of those technologies, it's finding the sweet spot to provide sufficient duality, diversity and redundancy in order to support CNI," he said.

Inside GNSS contacted a number of UK space industry players who largely declined to comment on the current state of UK GNSS affairs, citing, among other things, "commercial sensitivities" around the topic. There can be little doubt that they will all be watching developments with keen interest and seeking to participate in the still-to-be-defined program.

As far as a timetable is concerned, Annett said, "It's really difficult to answer that question, because that would infer that we know what we're going to deliver. What I can say is that over the next few months our intention is to analyze what's out there and then present options. That's not going to happen overnight. When we've got those options, we'll need to examine them, to say, right, what gives us the best bang for our buck? And part of that is a timeliness element. There's a risk associated with that. What's the threat and how long can we carry that risk."

Still with Benefits

Like every other country in the world, the UK will continue to enjoy free access to the open Galileo signal. In addition, the European Commission is committed to delivering in the near future a free high-accuracy service (HAS), and the Galileo commercial authentication service (CAS), though its final configuration is yet to be determined, will also be available to UK users.

One European Commission officer within the Galileo program, who prefers not to be named, told us, "I don't see a reason why the services within my scope—OSNMA/HAS/CAS—will be different for the UK, as a user, than for any other user. Apart from the SIS, which is accessible worldwide, both OSNMA, HAS and possibly CAS will have a ground channel support, which should be part of the service. At the moment, but this is my personal opinion, there is no reason why any of these would not be available for the UK too. In terms of general benefits, one benefit of Galileo is not only being a user of its services but also participating in its development. I think in this part the UK may lose its benefits."

The Crown Jewel

No longer an EU member, the UK will not automatically be allowed access to the secured Galileo Public Regulated Service (PRS), the encrypted signal, robust to jamming, intended for military, security and strategic infrastructure—unless it requests such access, and then pending negotiations.

Under the applicable legal framework, third countries can use the PRS provided a defined set of agreements is concluded. Such agreements could cover the manufacturing, under specific conditions, of PRS receivers, with the exclusion of security modules. And in case anyone is interested, and the UK might well be, the EU is currently negotiating such agreements with the US and Norway. The US requested an opening of talks some years ago, and a number of rounds have taken place.

"We will continue to draw the open signal, as anybody will," said Annett, "but our ability to influence the PRS will no longer be there, so we wouldn't anticipate being able to use that for defense or for critical national infrastructure, hence the reason for making sure that we can look at our own capabilities for space-based PNT.

"The PRS piece is absolutely critical, both from a security and a CNI (Critical National Infrastructure) perspective, and that's the crown jewel of Galileo. So you have to come up with some form of assured signal in order to make sure that you can protect that critical national infrastructure, and also the security elements within defense."

The European Commission communicated that the EU has offered to cooperate with the UK on Galileo through a PRS access agreement. So far, however, the UK has not submitted a request to open PRS negotiations. As noted, the UK already has the use of the encrypted US GPS signal for military use.

For now the UK independent PNT program will likely continue to exist in "shadow" form, much like a shadow cabinet—a possible alternative without actual power. Whether the UKSA's options and analyses produce an actionable outcome remains very much to be seen.




Development status of an alternate approach to regain EGNOS Safety-of-Life (SoL) services for the UK

• June 8, 2022: 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. 2)

- 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.


Figure 1: Inmarsat's London headquarters (image credit: Inmarsat)

- 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.


• October 18, 2021: The UK has ruled out the possibility of rejoining the European Union's (EU) Galileo project. 3)

- Brexit Britain was kicked out of the EU's Global Navigation Satellite System (GNSS) after cutting ties with the bloc. Civil servants and industry insiders have pushed for the Government to revive talks on rejoining – and the EU appeared to open the door to talks. In June, Timo Pesonen, the European Commission's Director General for Defence Industry and Space, said: "The European Union is open to negotiating with the UK on its participation in the EU space programmes. The ball is in London, not here."

- But can confirm that the Government has no plans to play ball with Brussels.

- Instead, the UK will continue to depend on the US Global Positioning System (GPS) for position, navigation and timing (PNT) services until a suitable replacement is selected.

- A spokeswoman from the Department for Business, Energy and Industrial Strategy added: "The UK no longer participates in Galileo as it did not meet our security, defence and industrial requirements."

- The hunt for a UK replacement is now understood to have filtered down to around 10 options that will be presented to the Government in November.

- A number of options have already been touted, including the OneWeb low-Earth orbit (LEO) satellite constellation.

- The Government invested £364million ($500million) to acquire the satellite company OneWeb from bankruptcy, in conjunction with the Indian company Bharti Global.

- OneWeb was designed as a broadband constellation first and foremost – it will provide rural 4G, and one day 5G, Internet signals across the nation.

- But now, OneWeb's Gen2 satellite is being tipped as a potential Galileo replacement with groundbreaking technology to meet the needs of Government, military, maritime and first responder customers.

- It comes after US company Kymeta announced it successfully tested its u8 broadband terminal with OneWeb.

- Kymeta and OneWeb performed a series of LEO satellite acquisition, tracking and throughput measurements in Toulouse, France.

- It is understood that the technology could be integrated into OneWeb satellites to provide solutions that meet the needs of Government, military, maritime and first responder customers.

- OneWeb is working with a portfolio of companies, including Hanwha, which recently invested £200 million in the operator.

- Hanwha made the investment via Hanwha Systems, the defence systems division that last year acquired Phasor Solutions, a British satellite antenna start-up.

- Neil Masterson, OneWeb chief executive, said Hanwha would also bring "advanced defence and antenna technology" to the table.

- Galileo, which will go live in 2026, features a Public Regulated Service (PRS) that can be used by government agencies, armed forces and emergency services.

- The bloc decided this "crucial feature" would only be accessible for EU members, despite the UK developing its "brains and heart".


• February 5, 2020: Hidden away in the document laying out the starting position for EU and UK negotiations lies an interesting nugget for those following the tortured tales of the European satellite navigation system, Galileo. 4)

- With Brexit "done" (we have a tea towel on order saying it so it must be true), the starting position for the future relationship has been published [PDF] and, as expected, it appears the UK will have access to the Public Regulated Service (PRS) of Galileo required by the military.

- It just won't be able to participate in developing the thing, and its use must also not "contravene the essential security interests of the Union and its Member States", which will doubtless set the "take back control" crowd a-frothing.

- For those lucky enough to have missed all the twists and turns in the previous season of Blighty's attempts to depart the European Union (so convoluted that even Netflix might say "steady on"), Galileo was one of those moments of awakening when UK lawmakers realised that if you leave a club, you also lose access to its toys.

- The UK was also blocked from working and bidding on sensitive parts of the system, much to the outrage of politicos taken by surprise at the prospect of not having access to a system into which Blighty had poured funds.

- Toys were subsequently flung from the pram and the UK stomped off, clutching its bat and ball and saying, in a wavery playground "Star Trek is better than Star Wars" voice that it would build its own version. So there.

- The UK military already has access to sensitive bits of GPS, and Galileo's PRS would, certainly initially, be a handy backup. Access to PRS could also render redundant the proposed multibillion-pound Brexit Satellite (BS) system to give the UK its very own sat-nav system.

- That access does, of course, depend on a deal being signed, and the EU's starting point is clear.

- And then there is the question of national ego. Dr Bleddyn Bowen, lecturer in International Relations and Space Policy at the University of Leicester, told The Register: "I don't know what prestige will be gained as the UK GNSS or Brexit System is widely seen as a waste of resources."

- He added that the BS was regarded by many in the space community as "a political vanity project".

- The final paragraph (136, b) of the section on Space also requires reciprocal access should the BS go ahead. Never let it be said that Eurocrats don't have a sense of humour.

- We asked the UK Space Agency, tasked in August 2018 with leading a £92m effort to look at Brexit Satellite options, for its thoughts on the EU's opening position.

- The agency was unable to comment, but did direct us to a statement from then-prime minister Theresa May, to the effect that if the UK was excluded in the development of Galileo it would not seek access to the PRS.

- The agency is still "assessing what a UK system could look like, and how it would meet our needs", according to a spokesperson.

Bye-bye Blighty

- ESA began shunting Brits from Galileo last year. A worker within the agency told The Register that pretty much all UK citizens were being shifted from EU-funded programmes such as Galileo and EGNOS (rather than just those working on classified elements) and another confirmed that Brits were indeed on the move.

- Paul Verhoef, ESA's director of navigation, told us: "The EU satellite navigation programmes (Galileo, EGNOS, and related R&D) that ESA implements are subject to EU rules, including on security. ESA is committed to respect and implement these rules based on the Need-To-Know principles for classified and PRS material, and established through the security framework established within the ESA-EU Security Agreement.

- "The measures taken by ESA are fully in line with these principles and rules and take account of the foreseen change of status of the UK within the EU. Therefore, unless certain security agreements are in place by the foreseen date of Brexit on 31 January 2020, the status of UK nationals, and their access rights to the information in the programmes, will change."

- The UK Space Agency would not be drawn on the fate of those shifted onto other work (if ESA employees) but did tell us: "The UK will continue to play a leading role in European Space Agency programmes, from missions to Mars to Earth observation and advanced telecommunications. The work to develop a UK Global Navigation Satellite System, as an alternative to the EU Galileo system, is progressing well."

Behold, the Brexit Satellite

- Should the UK find something better on which to spend the BS billions, and make use of the Galileo PRS instead, Dr Bowen observed that "the GNSS industry can fall into line with all the other industries that are finding it hard going thanks to Brexit".

- And lawmakers? "The UK Gov is playing up the bluster and drama for domestic news consumption," said Dr Bowen.

- "The choice later in 2020 will be either what the EU is willing to give," of which we have a relatively good idea thanks to Monday's publication, "or 'no deal'.

- "Which now," he added, "has around a dozen different aliases."

- It wouldn't be the end of the world if 2021 rolls around and quivering fingers are pointing. "Britain could still try to negotiate on it separately again in future if it and the EU wishes," said Bowen.

- "It is in the EU's defence and security interests to have the UK able to use the PRS element of Galileo as a passive user."


• December 12, 2018: The row over the the United Kingdom's attempt to stay fully involved in the European Union's global satellite-navigation (satnav) system, Galileo, after it departs the bloc, is back in the headlines after science minister Sam Gyimah cited it in his resignation statement last month. 5)

- Gyimah's resignation came hours after UK Prime Minister Theresa May had said that the UK government would end talks with the EU on Galileo, and would instead consider building its own global satnav system for use after Brexit.

- That idea was first floated by the government in May, but many experts have dismissed it as too expensive, unnecessary and even unfeasible — the lack of available space on the radio spectrum to run such a system could be a show-stopper.

What did the science minister say about Galileo when he resigned?

- Gyimah resigned in protest at the Brexit divorce agreement reached last month by the United Kingdom and the EU, and over discussions about Galileo. He said that the EU's superior hand in negotiations over the programme convinced him that Britain would fare badly in future negotiations on many other issues, including research, should the divorce deal go ahead. (The deal prompted a spate of other ministerial resignations, and its fate is currently uncertain.)

What is Galileo, and why is it so important?

- Galileo is one of four global satnav systems, which provide myriad civilian, scientific and defence services. The others are the US Global Positioning System (GPS), Russia's Global Navigation Satellite System (GLONASS) and China's BeiDou, which will be fully operational in 2020. The EU started the Galileo programme in 1999 to break its dependence on GPS and GLONASS.

- The Galileo constellation — comprising 26 satellites — was completed this July; a near-complete constellation began beaming down signals free of charge to smartphones and other receivers in December 2016.

- Most modern satnav receivers combine signals from all four systems to increase accuracy and reliability. Researchers also combine signals and use them in an array of scientific applications, including the monitoring of movements in Earth's crust and studying the atmosphere.

- The Galileo programme is building another 12 satellites as in-orbit spares and to replace older craft. It is also starting to build a next-generation system that would come into service around the middle of the next decade. The EU opened the first of the tenders for building these craft in June.

Who paid for Galileo and how much did it cost?

- The project is funded through the EU's budget. Total costs are estimated at around €13 billion (US$15 billion) to €15 billion to the end of 2020.


Figure 2: The European Union's Galileo network (artist's impression) is a global satellite-navigation system (image credit: DPA Picture Alliance/Alamy)

How would Brexit change the United Kingdom's participation in Galileo, and why is the UK government unhappy?

- Brexit itself would have no effect on the availability of Galileo signals to scientists and other UK citizens — the service is freely available to anyone on the planet.

- But a UK-based company, Surrey Satellite Technology (SSTL) in Guildford, a subsidiary of the aerospace giant, Airbus, made all the satellites built so far — although many components, such as the satellites' atomic clocks, are sourced from suppliers in Europe.

- After Brexit day on 29 March next year, the UK would enjoy a transition period until the end of 2020 during which relations in many areas would stay much the same. But the EU has already effectively excluded UK companies — and therefore SSTL — from bidding for the lucrative tender for the next-generation satellites. It also ignored a plea by Gyimah to postpone the tender to allow more time to seek an arrangement.

- The UK government complains that this treatment is unfair given that it has so far contributed around 12% of Galileo's budget — about €1.4 bn.

- But economically, the UK has been a net beneficiary of the project, points out Bleddyn Bowen, an expert in international affairs at the University of Leicester who has studied the impact of Brexit on space policy. The country has won back some 17–19% of Galileo's total budget in industrial and research contracts. These returns have in turn strengthened the UK space industry's science and engineering capabilities, he adds.

- The UK government is also unhappy that after Brexit day, under EU rules, it automatically stops having access to or being involved in the defence-related and classified aspects of the Galileo programme — something it had hoped to remain a part of.

What are Galileo's defence applications?

- The system's secure service, scheduled to be fully operational by around 2026, would be restricted to government-authorized users, including the military and essential services such as energy companies and telecoms. The signals are encrypted to control access, and protected to stop interference or malicious jamming.

- The United Kingdom has been closely involved in the secure system's development, and built much of the related cryptographic equipment. It argues that this close participation, and the UK's significant role in EU defence matters, mean it should be given special treatment allowing it a full role in the inner workings of Galileo's defence aspects and its industrial pay-offs.

- The EU had said that the United Kingdom could apply to access the encrypted signals after Brexit, as is possible under a 2011 EU law for third-party access; the United States and Norway have already applied. But EU rules (which the United Kingdom helped to draft) do not allow a non-member state to be involved in continued research, development and procurement of the security aspects of Galileo.

- The United Kingdom said that this is unacceptable, leading May to say earlier this month that the government would abandon plans to use Galileo for defence and critical national infrastructure. She also confirmed that the United Kingdom was looking at options for building its own global system.

Is that proposal credible?

- It might be technically feasible, say experts — the United Kingdom has the science and engineering skills to build such a system — but it probably isn't affordable.

- Widely cited estimates put the cost of building a system at somewhere between £3 billion (US$4 billion) and £5 billion. That doesn't include the running costs, which amount to about €800 million a year for Galileo. For comparison, the UK space agency's budget this year is £402 million, and entire UK defence research budget will be about £1.9 billion next year.

- "Spending £3 billion to £5 billion on a UK system would be grotesquely wasteful," says Robert Massey, deputy executive director of the UK Royal Astronomical Society in London.

- The money would be better spent on more-pressing UK defence priorities and industries in space, rather than on duplicating what already exists, says Bowen.

- In August, the UK government said that it was setting aside £92 million to design the proposed system. That sum alone exceeds the UK budget for basic astronomy research, says Massey.

- But even if Britain were to build its own system, there could be a crucial technical limitation: the lack of suitable space on the radio spectrum.

What's the issue with the radio spectrum?

- The four existing global satnav systems already take up the part of the spectrum allocated for satellite navigation by the International Telecommunication Union (ITU), which regulates spectrum allocations, says Alexandre Vallet, head of the ITU's Space Services Department in Geneva, Switzerland.

- Squeezing a new global system into this spectrum would require novel radio-signal designs that don't interfere with other systems, says Vallet. And these would need to be endorsed by international agreements.

- Failing that, Britain could request an ITU World Radiocommunication Conference — a meeting held to review and revise the international treaty governing the use of the radio-frequency spectrum — to allocate more spectrum for satnav systems, says Vallet.

- But that part of the spectrum is already under heavy demand from many other applications, such as mobile phones and aeronautical and military radars, so it would still be a challenge to make room for another global satnav system, he says. Such a move would also need Britain to gather considerable support from other countries, he adds.

How is this likely to play out?

- After Brexit — whatever form it takes — the EU is likely to consider the UK as a third country in Galileo, says Federico Santopinto, a researcher at the Brussel-based Group for Research and Information on Peace and Security — so involvement in developing the secure programme would be off the table. The EU will probably eventually allow the United Kingdom to receive Galileo's secure signals but entirely on its terms, he says.


1) "The Rocky Road To A UK GNSS," Inside GNSS, 30 November 2020, URL:

2) Jason Rainbow, "Inmarsat satellite tests signal for replacing lost UK navigation capability," SpaceNews, 8 June 2022, URL:

3) Callum Hoare, "Galileo rejection: UK slams door in EU's face and RULES out return over security fears," Express.CO.UK, 18 October 2021, URL:

4) "EU tells UK: Cut the BS (Brexit Satellite), sign here, and you can have access to Galileo sat's secure service," The Register, 5 February 2020, URL:

5) Declan Butler, "Could the United Kingdom really build its own global satnav system?,Britain has abandoned plans to rejoin the EU's Galileo network for defence and critical infrastructure after Brexit — but the alternative faces major hurdles," Nature, 12 December 2018, URL:

The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (


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