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The UK government's drive to develop its own space sector could help provide solutions to the maritime industry's reliance on GPS. David Appleton reports
Since the first satellite was launched in 1978, global navigation satellite systems (GNSS) have become indispensable to the shipping industry – not to mention a host of other industries which are reliant on GNSS for position, navigation, or timing applications.
The Global Positioning System (GPS) developed by the United States military is the best known GNSS and the one still used by most vessels. Despite the undoubted safety and economic benefits, one question has lingered ever since the first GPS receivers were installed on ships: what happens if they go wrong?
In a world where many deck officers have never experienced life without the ability to read their position off a screen, the use of traditional navigational techniques is falling into decline, and there are questions to be asked as to how practical it would be to fall back onto celestial navigation on a modern bridge with no paper charts.
Warning signs of a wider crisis
Incidents that demonstrate shipping's vulnerability to interference from either natural disturbances or deliberate 'spoofing' or 'jamming' are a regular occurrence, with the United States Coast Guard Nav Centre listing no fewer than eight maritime incidents so far this year. These have ranged from intermittent loss of signal to complete loss of position for periods of several hours.
While in some cases military involvement is suspected – such as the 2017 case where more than 20 vessels in the Black Sea reported problems with their position due to deliberate spoofing – the availability of cheap jamming equipment for purchase online means that issues can just as easily be caused by private individuals, either deliberately or inadvertently.
We must stop putting all our eggs in one basket
Recognising the potential for disastrous consequences from manipulation of a vessel's GPS signal, the International Maritime Organization (IMO) identified the need for resilient position, navigation and timing (PNT) as one of the core objectives for its strategy on e-navigation. This recommends integrating a range of different sources of PNT information in shipboard receivers which can both provide redundancy in the event of failure and also a cross-checking capacity to protect against spoofing.
Multi-system receivers are available that are capable of handling signals from alternative GNSS such as the Russian GLONASS, European Galileo or Chinese Beidou systems. These offer a simple way to achieve more resilient PNT; however, as they all operate on essentially the same frequency, they are all equally susceptible to jamming.
Terrestrial backup options
Prior to the development of satellite navigation systems, a multitude of ground-based systems existed, including Decca and Loran. E-Loran, the successor to Loran, is widely accepted as the best available terrestrial, wide-area PNT system, and was actually operational in the UK on a trial basis in 2014-2015.
These terrestrial-based systems have the advantage of being entirely independent of the space-based segment of GNSS, and would remain operational in the event of complete loss of satellite signals. In addition, because the signal is much more powerful than GNSS, it is much less susceptible to jamming.
Unfortunately, despite high levels of support from the maritime community, the UK General Lighthouse Authorities (GLA) were forced to close the service in late 2015 when other European countries took the decision not to maintain the transmitters required to keep the service operational. They cited high costs and the enhanced resilience of the Galileo signal to spoofing, although, as critics pointed out at the time, the Galileo signal is just as susceptible to jamming.
Government recognition of the threat
The potential for catastrophe if there were to be any significant outage of GNSS is well understood. A 2017 study by London Economics estimated the cost to the UK alone from a five-day loss of GNSS at £5.2 billion. However, the fate of the UK e-Loran trials is testimony to the difficulties involved in persuading governments to invest in projects to prevent events that would undoubtedly be high impact but 'might never happen'.
Fortunately, those calling for the UK government to take some concrete action have received a welcome boost in the unlikely form of the fallout from Brexit and the government's renewed desire to make the UK a global player in the space industry.
When it became apparent in 2018 that the UK would no longer be involved in the European Galileo system, the government announced a £92 million, 18-month feasibility study into the design and development of a home grown GNSS. However, these plans were scrapped in September 2020, with the programme being 'reset' as the Space Based Positioning Navigation and Timing Programme (SBPP).
The SBPP aims to 'explore new and alternative ways that could be used to deliver vital satellite navigation services to the United Kingdom' which are critical for both civilian applications and national security, while 'boosting the British space industry and developing the UK's own capabilities in these services.'
Time for UK satellites to shine?
The SBPP has been tasked with considering 'the widest set of options for space based PNT', with options thought to include providing supplementary signals from existing geostationary satellites or repurposing satellites from the bankrupt communications company OneWeb following the government's controversial $500 million acquisition of the company in 2020.
The company currently has 136 satellites in orbit of a planned 648 satellites. These are primarily aimed at providing a worldwide space based broadband service to rival the US-based Starlink Service currently being set up by California based SpaceX, but it is thought that the OneWeb satellites could be repurposed or that their primary signal could be used for augmentation. This speculation has increased since it was confirmed that the company has responded to the Request for Information (RFI) issued by the government to collect novel space-based PNT ideas.
While the headlines have focused on the space-based proposals for securing resilient PNT, it is recognised that investment into both future and existing PNT solutions should consider both terrestrial and space-based systems, and that an assured 'system of systems' approach is required without single points of failure. It is likely that final plans will form part of the UK's National Space Strategy due to be published this year.