The United Kingdom’s (UK) Skynet 6 satellites are obsolete before they have even been launched. So, what should the next generation of British Military Satellite Communications (MILSATCOM) satellites look like?
The four Skynet 5 satellites were launched into Geostationary Orbit (GEO) between 2007 and 2012. Assuming a typical design life of 15 years, the first would have exceeded its design life from 2022 and the remainder from 2027, to be replaced by the Skynet 6 satellites. Commercial satellites often remain in use beyond their design life, but that is not a desirable scenario for satellites used in potentially critical situations, such as MILSATCOM.
It follows then that with a lead time of 5-7 years, the replacement Skynet 6 satellites should have been ordered by 2017. However, this was not done until July 2020, when a sole-source £500 million contract for the build and launch of the Skynet 6A satellite, intended as a ‘gap filler’, was awarded to Airbus Space and Defence UK, with service entry in 2027. The remainder are yet to be ordered.
In-orbit threats
In recent years, satellites designed for military use have incorporated protection against electromagnetic events, such as Electromagnetic Pulses (EMPs) generated by nuclear explosions. In the future, it is more likely that threats will come from directed energy weapons, both electromagnetic and kinetic. As long ago as 1985, a defunct United States (US) satellite in a 600 kilometre Low Earth Orbit (LEO) was shot down by a missile launched from an American F-15 aircraft. Since then, several sovereign states have used terrestrially-launched interceptors to attack satellites in LEO.
Disabling satellites by kinetic means in higher orbits, such as Medium Earth Orbit (MEO) or GEO, is also possible, but would require the use of larger (and more expensive) ground-launched interceptors. In parallel, many of the capabilities which already exist – or are being developed – for commercial in-orbit servicing could equally be applied to an Anti-Satellite (ASAT) capability, using optical or radar sensors to locate and target a spacecraft with the objective of causing damage.
A satellite is fundamentally fragile. Physical contact with a foreign body of any nature would degrade its ability to fulfil its mission, and thus needs to be prevented. Therefore, the next generation of resilient MILSATCOM satellites will need to incorporate a means of disabling, or ‘blinding’, these sensors. Such a capability could also mitigate the threat from directed energy weapons by rendering optical or radar-based targeting systems unusable.
Orbits and coverage
GEO has always been the orbit of choice for MILSATCOM and commercial satellite operators alike. However, in order to meet the increasing demand for faster data rates and lower latency, many commercial operators are turning to lower orbits, such as MEO, LEO and Very Low Earth Orbit (VLEO). Should the military follow suit?
GEO is a stable, well-regulated orbit; cost-effective for providing global communications and high enough to be a challenge for ground-launched kinetic attacks. It is also backwards-compatible with legacy Skynet ground equipment. However, with a north/south coverage limit of around 70° latitude, coverage of polar regions is not possible. GEO coverage can be complemented in polar regions by a constellation of at least three satellites launched into a Highly Inclined Elliptical Orbit (HIEO) to provide either North or South polar coverage, but not both.
A satellite constellation in LEO provides true global coverage, and meets the increasing demand for faster data rates and lower latency. However, downsides such as substantial cost, shorter in-orbit lifetimes, vulnerability to ASAT strikes and the increasing risk of a catastrophic Kessler event makes LEO undesirable as the basis for a resilient sovereign SATCOM capability.
MEO offers a balance between the coverage of GEO and the low-latency of LEO, needing at least six satellites in a single orbit to provide contiguous coverage. Current commercial MEO services operate in an equatorial orbit, providing coverage between ~50°N and ~50°S. In order to provide global coverage, two further orbits at inclinations of 60°N and 60°S would be needed, operating with a minimum of six satellites per orbit for a total minimum of 18 satellites in three orbits.
Such an approach also lends itself to a phased rollout, where the first six satellites are launched into an equatorial MEO orbit to provide next-generation capabilities in the ±50° latitude regions. Higher latitude and polar coverage would be achieved with subsequent inclined-orbit launches.
Payload capabilities
The UK’s Skynet satellites have always used the legacy X-band and Ultra-High Frequency (UHF) MILSATCOM bands, with the X-band as a tradeoff between resilience to atmospheric attenuation and reasonably high data throughput. The American Wideband Global SATCOM (WGS) satellites and British Skynet 5 satellites have, for many years, supported both X-band and Ka-band, providing a balance between the high data rates achievable with the Ka-band and the resilience of the X-band. Any future UK MILSATCOM payload will need to support these legacy bands alongside new capabilities, including ASAT defensive measures.
Inter-satellite optical links have become widely used, and it would be a missed opportunity not to incorporate such links in future to increase resilience in satellite-ground communications. If a ground station is lost, an inter-satellite link would enable traffic to be routed via another satellite to an alternate ground station.
Ground segment
The UK’s current ground segment is based on geostationary SATCOMs, employing ground systems with limited or no tracking capabilities. Thus, if orbits other than GEO are to be considered for next-generation MILSATCOM, a significant upgrade in ground technologies will be required to provide a satellite tracking capability.
In recent years, there have been significant advances in the performance of Electronically Steered Antennas (ESAs), which can provide satellite tracking with much more compact equipment than if using a classic parabolic antenna design. Such technology sees widespread use in the Starlink system, and ESA technology has now reached a level of maturity such that it should be applied to military use. ESAs employ phased array technology, which enables seamless handovers between satellites and the creation of ‘nulling’ zones to mitigate the effects of hostile jamming. Such capabilities are desirable, regardless of the satellite’s orbit.
Sovereign capability
What defines a British sovereign capability? Do participants in the Skynet programme have to be UK companies, or have just a corporate presence in the country? Participation in IRIS2, the European Union’s (EU) secure SATCOM programme, requires all participants to be EU-incorporated organisations, not subject to control or influence by a non-EU entity.
Could the British satellite industrial base support such a definition? Probably not, but overreliance on non-sovereign capabilities and technologies leads to significant, undesirable operational dependencies on overseas contractors – as seen with the F-35 Joint Combat Aircraft and Trident nuclear deterrent programmes.
From a cost perspective, where is the balance between capability and affordability? A three-satellite GEO-based network is the most affordable option, but it is unlikely that such a solution will provide the future MILSATCOM capabilities which the UK requires. Conversely, a LEO-based solution is probably unaffordable, and in any case may not be the most suitable option for a resilient sovereign MILSATCOM capability. As such, it would seem that a MEO-based solution is worth further investigation.
MEO would provide a truly global solution, but can Britain afford it? Should it consider a shared capability with other trusted sovereign states to fund such a system? Trusted European neighbours are already committed to IRIS2, but what about looking further afield – say, to the UK’s Five Eyes intelligence alliance partners? A MEO-based solution lends itself well to a ‘time-share’ arrangement, providing that the partners are geographically dispersed so resources can be shared effectively.
Conclusion
The Skynet 6A satellite currently on order is needed to provide resilience for the ageing Skynet 5 fleet. However, is it really worth continuing with a MILSATCOM programme which is looking outdated now, and by the time of launch in 5-7 years will certainly be obsolete?
To conclude, the Skynet 6A satellite should be launched as planned, but no further Skynet 6 GEO satellites should be ordered. A fresh approach is needed; one which can deliver services more capably and cost-effectively, using a MEO-based constellation as described, and potentially in collaboration with trusted allies and partners.
John Yates is an expert in satellite communications and technologies. He currently works as a freelance consultant, advising companies and organisations in commercialising new satellite technologies.
The views expressed in this article are personal to the author, and do not necessarily reflect those of the Council on Geostrategy.
To stay up to date with Britain’s World, please subscribe or pledge your support!
What do you think about this Memorandum? Why not leave a comment below?