Satellite to satellite communication, or inter-satellite links (ISL), are becoming both an increasingly important and ever more complex challenge in today’s industry.
With data collection and processing volumes growing in orbit, and new satellite constellations requiring higher levels of coordination, it’s easy to understand why.
Here are a few engineering and design considerations for ISL use:
Satellite data exchange facilitates multiple applications – when satellites act as consistent nodes on a network, it can open up new operating concepts and even business models.
Inter-satellite ranging is crucial for high-frequency remote sensing – ISL is needed for applications that require precise satellite to satellite communication to measure the distance between each, so that data from the different passes can be coordinated.
Data security and cybersecurity – ISL must be secured to at least the same level as the space-ground data connection to ensure cyber threats are minimized. And, if data is passing through satellites or processing chains involving more than one operator (or is data from/for multiple end-users) effective encryption is needed to sure confidential information remains secure.
Traceability – following from the previous point, to ensure that problems or inefficiencies in the satellite to satellite comms chain can be identified and fixed, the system needs to be auditable, with accurate telemetry metadata accessible by the operations team.
MissionOps impact – while ISL communication can bring benefits, it can also add complexity to operations. Unless the satcomms chain is largely automated, increasing operator decisions could be a factorial problem, slowing down the system.
Enabling engineering – the two forms of satellite to satellite communication are RF comms and Free Space Optical (FSO) or lasercomms. RF links between satellites vary slightly to RF ground-space links, and will require limited engineering changes. Lasercomms on the other hand requires precise pointing to ensure line of sight, and so may need more extensive redesigns.
These are just a few of the engineering challenges, and opportunities, that satellite to satellite crosslinking communication brings.
Ultimately, ISL quality and efficiency relies on high quality communications hardware in orbit. And the best place to find it is on the satsearch multi-vendor supply chain hub, right here.
And, in designing a satellite to satellite system, it will be important to consider how it would be used in the future, as well as how it meets today’s operational requirements.
Building for future communication needs
From a communications perspective, for satellites to operate as effective relay stations in orbit – i.e. receiving, modifying, and transmitting data consistently and without errors – the entire system needs to be optimized for the communication requirements.
This involves ensuring that individual satellite communications subsystems and components are high-quality, robust, and work well together. And it also involves ensuring interoperability with the rest of the system.
As the use of artificial intelligence (AI), edge computing, and on-board data processing (OBDP) proliferates, and with the growth in more versatile, multi-objective, even multi-orbit missions, this is an increasingly complex challenge.
Today’s satellite constellations are built in iterations, with one or a handful of first-generation systems launching and, if profitability (or at least operational stability) is achieved, the next generation is then engineered.
And while no operator can yet match Starlink’s velocity for this, small companies dedicated to developing a genuinely sustainable commercial service will look to use every opportunity to improve on previous designs, cost-effectively and while balancing consistency.
So, when it comes to satellite to satellite communications, ISL systems must be developed with these future scenarios in mind. Optimizing channels, communications frequency, transponder use, amplification and modification, and other aspects of the satcom chain is about engineering for tomorrow’s service expectations as well as today’s mission requirements.
Ensuring orbital safety
By far some of the most compelling potential applications of high-speed satellite crosslinks is in space situational awareness (SSA) and space traffic management (STM).
Here are some prospective use cases for ISL technology in these areas:
- Orbiting satellites autonomously communicating and maneuvering to avoid collisions,
- Satellites that identify space debris can broadcast the data on it to nearby birds that may need to adjust flight paths or operations accordingly,
- Systems communicating on congested bands may be able to re-route or manage their data exchange using satellite cross-links to contact the ground,
- Satellites can communicate on, and work to mitigate, system errors, failures, and even space weather effects, via cross-linked communication back-ups,
- Multiple satellites can make and utilize coordinated ranging measurements of debris or other operational satellites without ISL technology (or that are unable/unwilling to communicate with third-party systems) and communicate the results to the ground or other systems,
- Satellites that are in contact with the ground may receive data on debris or traffic and then pass this on to others that are not reachable at the time, or to systems in other orbits, cis-lunar, or deep space, and
- A constellation of satellites with ISLs can act as a backup network for all aspects of sustainability related data exchange, enhancing knowledge about the orbital environment in real-time for operators everywhere.
Ensuring that Earth’s orbits are safe and accessible is increasingly expected to be the responsibility of individual mission operators as well as agencies and governments via regulators.
And although supporting this objective using satellite to satellite communication will require something of a step-change in collaboration in space – the benefits should be felt by all stakeholders across the global community.
To get started designing your inter-satellite link solution, take a look at our supply chain hub for commercial satellite communications equipment here.
