Mega-constellations are composed of several hundreds of highly networked satellites in low Earth orbit, and they are fundamental in providing uninterrupted communication through networks across the globe, enabling internet access even in remote areas.
The space industry has shown great interest in mega-constellations due to their expected high return on capital invested. SpaceX, via its Starlink satellite internet constellations, has already launched 60 satellites into low-earth orbit (LEO) in May 2021. It plans to launch thousands more in the coming years as part of its mega-constellation project. OneWeb, Amazon, and several other private space companies have similar ambitions.
Unregulated launches of mega-constellations, however, make low Earth orbit too crowded to function safely and securely. Such congestion increases the risk of collision, such as with other active satellites, untracked debris, and meteoroids. Even a single collision in outer space can cause significant cascade effects, creating future collisions, as collisions ‘give rise to more debris and lead to more collisions’.
Near misses provide learnings
Space-faring nations and the space industry should learn from the several near miss incidents that have already taken place with single satellites and mega-constellations in outer space.
In 2018, the mission controllers of the CryoSat-2, a satellite that monitors precise changes in the thickness of polar ice sheets, had to manoeuvre their satellite into a higher orbit to prevent collision with a piece of debris. In 2019, the European Space Agency (ESA) moved its earth observation satellite to avoid it colliding with a Starlink satellite.
The collision risk, in this incident, was estimated to be ‘ten times higher than the threshold that required a collision avoidance manoeuvre’. While manoeuvring away from a piece of debris is common practice, the space industry is still learning how to manoeuvre to prevent collision with an active satellite.
The latter requires direct communication hotlines between the operators involved, at all times. Current communication between operators, however, is conducted on an ad-hoc basis and over email exchanges. This is neither sustainable nor efficient as outer space becomes even more congested, exponentially increasing the risk of collision.
Academic assessments also reveal a grim picture for the future of the on-orbit environment. By using the European Space Agency (ESA)’s debris evolutionary model, researchers tested the probability of multiple collisions of mega-satellite constellations and identified ‘significant risk from non-trackable debris objects’.
These are objects smaller than ten centimetres in size. Although non-trackable debris generally poses non-catastrophic collision risks as a result of the existing shielding in the design of the satellites, these collisions may still be able to disable key satellite functions such as communications. The loss of critical functions may have cascading impacts not only on the overall health of the mega-satellite system in question but also on the functioning of critical national infrastructure on Earth.
Another risk relates to the proliferation of emerging technologies and their impact on outer space security. Research indicates malicious actors are already capable of manoeuvring a single unprotected satellite to have it collide it with another satellite or with a space object through cyber means.
And, although all satellites are vulnerable to cyber threats, mega-constellations require additional cybersecurity considerations because of their increased connectivity and the webbed nature of networks across units, for instance, through the Internet of Things (IoT) applications for communication purposes.
Recommendations for rules of the road
Due to the changing nature of the use of outer space and potential risks that mega-constellations pose to the safety and security of outer space, it is important to set out the rules of the road before it is too late to act.
- Set up specific regulations and policies around mega-constellations to ensure sustainable operations and to minimize the risk of collision. This should include considering new approaches for space traffic management as the capacity of ground-based platforms ‘may not be sufficient to monitor and control’ the increased number of satellites in the near future.
- Create codes of conduct outlining the norms, rules and responsible behaviours in outer space, not only for states but also for the private sector. This is particularly important to prevent the monopoly of control over certain orbital regions by a handful of actors (both companies and countries) and to ensure rightful and equal access to these areas for all.
- Establish clear hotlines for communication between operators and for the operators to test these hotlines through joint exercises.
- It is impossible to prevent cyberattacks in the space and ground domains. Instead, the mega-constellation operators should conduct risk assessments, have a clear risk mitigation policy (i.e., for cyber threats, collision risks etc.), and should apply redundancy measures to prevent catastrophic failure.
- The ESA is developing an automated collision avoidance system that relies on machine learning techniques. This automated collision avoidance system will drastically decrease the likelihood of an in-space collision, once the machine learns from near-misses and can better predict future scenarios. Regardless, the operators should train their staff in interpreting machine-made decisions. Keeping humans involved in the decision-making process at all times would aid this process. Overall, the operator needs to be able to trust the system’s capabilities, and without adequate testing and evaluation mechanisms, this cannot be achieved.