The Dynamics of Resilience
Often it is convenient to discuss complicated topics in a simplified manner to aid in communication. The drawback is that over-simplification can lead to a lack of important details that provide the necessary context to understand the concepts. Resilience discussions are often ripe with this kind of simplification that can lead to misunderstandings. One of the aspects of designing resilient space systems that is often under-emphasized is the fact that resilience, as a measurable quantity, is not generally a static value. It is a value likely to change over time as the environment and technologies also change. A system may be highly resilient to credible threats when first activated, but less resilient as the threats proliferate and evolve.
A recent example of this is reports of the regional radio frequency (RF) jamming of the Starlink system within Iran (https://www.techpolicy.press/what-irans-internet-shutdown-reveals-about-starlink/). Though public disclosures of the details are limited at the present time, multiple reports indicate that the Iranian government is using ground-based uplink jammers combined with local GPS jammers to inhibit the Starlink broadband service over large areas. Some reports indicate data rate reductions of over 80%.
Starlink, with over 10,000 satellites on station, has been the exemplar for the use of an extremely proliferated space architecture to achieve high resilience. It is a trivial exercise to show the math behind such a claim. However, there are always caveats related to the assumptions around the threat environment and methods of interrupting service. While the basic math is correct, the implementation of any space system likely include certain vulnerabilities or edge cases that could be exploited. This extends to both software and hardware. And the longer an adversary has to probe these potential weaknesses, the more likely they are to find them.
If indeed Starlink’s service is being inhibited, this is evidence that the resilience to certain RF threats is not as high as originally believed. This could be due to an lack of understanding of the threat, an undetected vulnerability of the system design, or some combination of both. And without remediation the likelihood of future threats further decreasing resilience could increase. Certainly the continued increase in the number of satellites will continue to increase system resilience, but since there are already 10,000 satellites in orbit there is a possibility of diminishing returns.
These cases of successful disruption of space systems further emphasizes the fact that an analysis of resilience is not a one-time calculation, to be used to steer the design and then retired to the archives until the next system design iteration. Instead, the resilience assessment must be a living process, aligned with updates to the situational awareness while constantly evaluating new threats to the system to ensure that its future capabilities and performance are not compromised.
