by Romain Buchs, Scientific Assistant at the International Risk Governance Center (IRGC)
The advent of large satellite constellations has drawn attention to the risks associated with increased activity in space. The growth in space traffic and the debris population, which results in more conjunctions, has highlighted the limits of our collision avoidance capabilities and processes. This observation has prompted governments and space actors to focus their attention on developing knowledge of the space situation and space traffic management. While these efforts are necessary to reduce the risk of collision, they are insufficient. Current strategies for dealing with the risk of collisions from space debris need to be strengthened, and there are new strategies that deserve greater consideration.
The risk profile of operational spacecraft is dominated by Lethal Untraceable Debris (LNT), objects too small to be tracked with current technologies, but which can still result in the deactivation of a spacecraft. These objects cannot be dodged by operational spacecraft and outnumber larger objects tracked by radar and optical sensors. The large population of abandoned objects dropped into orbit is clustered at different altitudes, posing a significant risk of generating more LNT debris in collisions. The extent to which these objects pose a greater risk to the space environment than large constellations is debated. It strongly depends on the size and altitude of the constellations finally deployed, as well as the level of mitigation measures implemented by the constellation operators.
Decision making in this area is very difficult. The risk of collision is technically complex, with many interconnections between risk elements, which are difficult to assess, in terms of likelihood of occurrence, severity, economic costs and broader impacts. The space ecosystem in which the risk thrives also presents a complex pattern of interconnections, with many links to other systems on Earth. There is pervasive uncertainty about the current level of risk and the effect of mitigation measures, as well as ambiguity about the current and future behavior of various space actors. Policy makers and space actors find it difficult to assess the severity of the risk and their tolerance to it. The prioritization of intervention strategies is complicated by the uncertainty associated with the cost of damage to satellites and the disruption of the services that depend on them. There is a lack of data needed to perform cost-benefit analyzes of mitigation and remediation approaches.
In this context, the International Center for Risk Governance (IRGC) of EPFL has just published a report entitled “Space Debris Collision Risks: Current State, Challenges and Response Strategies”. The report seeks to provide factual insight into the important technical, regulatory and economic aspects of collision risk, as a basis for much-needed deliberations on policy options in this area.
The current response strategy to ensure both the safety of short-term operations and the long-term stability of the space environment is based on mitigation: procedures and technical requirements for operational spacecraft aimed at reducing the probability of debris creation. Space debris mitigation includes shielding spacecraft, collision avoidance maneuvers, post-mission disposal, and disposal of end-of-life stored energy to limit the likelihood of an accidental explosion. Internationally agreed non-binding guidelines recommend the use of these technical measures and are supplemented by technical standards and industry-led best practices. International space debris mitigation guidelines are often incorporated into the requirements of national authorization procedures.
The current response strategy has a number of limitations. First, it mainly addresses the creation of new pieces of debris, without addressing the legacy of abandoned items. Second, overall compliance with internationally agreed guidelines is low. Third, national policies are not uniform and do not always implement these guidelines. Fourth, national requirements prioritize ex ante measures to minimize the potential creation of space debris from a mission; once in orbit, the policies in place provide little incentive for operators to reduce the risk of debris creation.
These limitations can be overcome by strengthening the current strategy and developing new ones. Strengthening the current strategy would involve:
- Strengthened surveillance and monitoring capabilities through new infrastructure, improved collaboration and new requirements for operators.
- Revise international guidelines with adaptive components to keep pace with scientific and technological developments.
- Design mechanisms to encourage countries to adopt national regulations aligned with internationally agreed standards.
- Adopt more stringent technical requirements than those in force at national level. Large space nations could strengthen their rules and foster change through reciprocity. Market entry conditions can be used to prevent forum shopping.
- Possibly introduce ex post sanctions in the event of non-application of debris reduction plans, which requires the development of effective monitoring systems.
- Develop mechanisms to finance space debris remediation, which aims to reduce risk once the debris has been created, and address cost allocation.
Remediation lacks funding and leadership from major space nations. Different methods have been proposed, such as actively removing abandoned objects from orbit (active debris removal), reducing the likelihood of a predicted collision by affecting the trajectory of one of the two pieces of debris ahead of time. planned collision (just to collision avoidance over time) and upgrading abandoned objects with collision avoidance capabilities (nanotugs). These methods have different risk-risk tradeoffs, are at a different stage of development, and are likely to result in different costs. Effective management of the risk of abandoned objects probably involves funding the development of these three methods.
To encourage space players to commit to their space debris reduction plan and to strengthen compliance with existing guidelines, a number of market-based solutions have been proposed. Some of them would not only incentivize risk reduction behaviors in space, but also provide a fund that could be earmarked for the development and implementation of corrective measures. Insurance is a key example, but given the uncertain legal framework and the remote nature of the space, it is unlikely to effectively reduce risk. Liability insurance premiums are priced according to the risk of loss and not the probability of a collision. As the probability of loss in the event of a collision is currently low, the mechanism for pricing third-party insurance premium rates cannot induce risk reduction behavior. Tradable permits (similar to a greenhouse gas emissions trading system) and regulatory fees (similar to a carbon tax) could be an effective way to reduce risk. Many forms of regulatory charges such as taxes levied at launch, for orbital use or for the generation of debris have been proposed. The mechanisms envisaged include deposit and reimbursement systems and performance guarantees. However, most of the proposals have only been developed at the abstract level and do not provide details on how they would be implemented. In particular, discussions on the unit of responsibility driving the risk, the trigger for the expense liability or its calculation period, and the mechanism for execution are lacking. More research and concrete proposals in this area are needed. While the research can help clarify the trade-offs between different implementations, the acceptable options will likely be determined by stakeholder preferences.
The intensification of space activities and the increased dependence of our economies on space infrastructures require technical and governance regimes more suited to the objectives. This article and the IRGC report have highlighted some of the limitations of the current approach to space debris and the challenges of managing the risk of collision. More concrete policy options that should be pursued will follow in a subsequent guidance note and article.
The EPFL International Risk Governance Center (IRGC) is an interdisciplinary unit dedicated to deepening knowledge about the increasingly complex, uncertain and ambiguous risks that affect society. We develop risk governance strategies that involve all key stakeholder groups, including citizens, governments, businesses and academia.