Yun ZHAO*
Keywords: Registration – Soft law – Space safety – Space traffic management – Sustainability
With the rapid development of space technologies, space tourism and transportation have become a reality and will continue to thrive in the process of space commercialization and privatization. It is obvious to all that the existing space law rules cannot meet the needs of future space transportation. It is time to seriously consider a possible legal regime to deal with space traffic management to ensure the safety of spacecraft in orbit and avoid potential collisions or accidents.
Space traffic management has a broad scope, covering the whole period from pre-launch, operation to re-entry of space objects. Space traffic management is defined by the International Academy of Astronautics (IAA) as “the set of technical and regulatory provisions for promoting safe access into outer space, operations in outer space and return from outer space to Earth free from physical or radio-frequency interference.” According to the Research Report on Space Traffic Management issued by the IAA in 2006, space traffic management, with the aim to maintain space order and protect space safety, includes at least three major areas: data collection and space situational awareness, space notification system, and specific traffic management rules.
Space traffic management is vital to the maintenance of space security and orderly development of space activities. Space safety, stability and sustainability are the cornerstones of all types of space activities. Creating a safe, stable and sustainable space environment is the common interest and responsible of all space-faring nations.
Avoiding collisions in outer space is a means to ensure space safety. Accordingly, space traffic management shall strive to avoid potential space collisions and ensure the safe passage of outer space and return to Earth. With a large number of moving space debris in outer space, there is a need to constantly update real-time data to avoid potential collisions. In addition to space debris, many satellites already in orbit have the potential to collide with other objects. There are normally two steps to prevent satellite collisions: collision risk assessment, and collision avoidance maneuver. Collision risk assessment is to predict the collision probability of an in-orbit space object with other objects. Collision avoidance manoeuvres are to take active actions by menoeuevering an in-orbit space object to avoid collisions. The effectiveness of these two steps relies heavily on the information sharing of the on-orbit positions of space objects in advance through space traffic management, so that all parties can reasonably predict and maneuver.
From the 1990s to the early 2000s, relevant discussions were still limited to the theoretical and conceptual stage. Starting from the 2010s, some concrete steps were taken to put academic discussions into practice. The Draft Code of Conduct for International Space Activities put forward by the European Union in 2014 reflects the initial steps in tackling the issue of space traffic management. During the annual session of the Legal Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS) in April 2015, the delegations of Germany and Luxembourg co-sponsored a new proposal to include a new agenda item on the exchange of views on the concept of space traffic management. The United States (U.S.) issued Space Policy Order No. 3 in 2018 with the aim to establish relevant responsibility and liability systems in the international governance regime for space transportation. Meanwhile, the U.S. Department of Defense issued a document entitled Space Defense Strategy in June 2020, which emphasized the importance of sustainability of U.S. space activities and its leading role in the negotiations for an international governance regime for space transportation. It is to be noted that the concept of space traffic management in the U.S. focuses on how to ensure national safety through the clarification of relevant criteria and requirements for traffic management; and the U.S.’ leading position in the space arena through the promotion of military-civilian integration.
The United Nations (UN) has played an important role in the enactment of space law rules and will continue its efforts in the field of space traffic management. The trend is clear that the UN aims to set up a pragmatic mechanism in coordinating and promoting cooperation among all States to facilitate the consensus-building process in order to reduce space collisions, enhance space sustainability and improve information sharing through space situational awareness mechanisms. In the meantime, the International Civil Aviation Organization (ICAO), as a specialized Agency of the UN, has also started concrete research work at the international level, it would be useful to examine possible measures to be taken in the interim before any legal framework is instituted. It is expected that the work on space traffic management will have a major impact on future development of space law.
The role of soft law rules for space traffic management
Space activities are closely related to national safety and security. However, with more and more states joining the space club, the consensus on a binding legal document becomes increasingly difficult. The whole process has been more complicated with the involvement of private entities. As such, there is a need to look to soft law rules for immediate solutions. In this regard, relevant soft law documents relating to space debris mitigation and space sustainability would help to clarify certain issues involved in space traffic management. Such documents include the UNCOPUOS Space Debris Mitigation Guidelines, the UNCOPUOS Guidelines for the Long-term Sustainability of Outer Space Activities, and the UN Group of Governments Expert (GGE) Report on Transparency and Confidence-building Measures (TCBMs) in Outer Space Activities.
An international regulatory body
It is essential to have an international regulatory body to deal with space traffic management for civil and commercial purposes. This entity would play a role in the coordination and enforcement of relevant traffic rules. Due account should also be given to issues such as space debris mitigation, space data sharing, and establishment of relevant safety standards. The principle of international cooperation has been emphasized on various occasions for space activities. No single country can effectively manage space traffic alone. Cooperation in space traffic management is of utmost importance to the success of future space tourism and transportation. A neutral cooperative platform through an international regulatory body shall be the ideal way out. The ICAO, in view of its rich experience in civil traffic management, shall be the ideal entity to take up this role. This body shall also work closely with the national entities in the field and coordinate their work at the international level.
Space situational awareness (SSA)
Space situational awareness, involving data exchange and information sharing, is essential for space traffic management. It refers to the recognition of the necessary and predictable space environment and the operational environment on which space activities depend, including the positions and movements of space objects in orbit. Accurate information on the location and surrounding environment of satellites and/or space debris is vital to the safety and security of space activities. SSA could be understood in a broad sense through three mission stages: 1) collecting various data of space objects; 2) analyzing the data to predict the probability of close encounter between two space objects and the risk of re-entry; 3) communicating with stakeholders about potential risks so that necessary actions can be taken.
At the moment, only a handful of States have space situational awareness systems and capabilities; no country can simply rely on its own efforts to achieve accurate cognition of all space objects in the world. Consequently, there is a need for the international community to share SSA data. Since the Outer Space Treaty or other existing binding space treaties do not provide for the duty to disclose and share SSA data, it is necessary to establish an international coordination mechanism for an integrated space situational awareness system, which can provide a reliable and accurate situational judgment source and foundation for space traffic management.
With the ongoing space commercialization and privatization, more and more private entities become the providers of relevant space data. The participation of private entities is undoubtedly conducive to the sharing of space data; however, no clear rules are in place regarding the rights and obligations these private entities enjoy in the process of data sharing. Accordingly, further rules should be clarified regarding the duty of data sharing in space traffic management, the scope, and standards for data sharing.
Very closely related to the SSA, registration of space objects is important in improving transparency in outer space and space activities. An important prerequisite for the successful development of shared space situational awareness is to ensure that the shared data is effectively regulated. The information provided in the registration can serve as the firsthand source for the SSA purpose. The Registration Convention and the UNGA resolution on improving the registration practice offer necessary rules on the registration of space objects. However, when space transportation becomes more frequent, there is a need to explore a separate/or different regime regarding the registration of spacecraft for the purpose of regular commercial transportations.
To conclude, peaceful exploration and use of outer space has always been the unremitting pursuit of mankind. With more and more States attaching importance to and actively participating in the development of space industry, space technologies are having a significant and far-reaching impact on the way of life of human society. At a new historical starting point, space traffic management has entered the public’s field of vision. While realizing that it may bring fundamental contributions to aerospace development, it is necessary to look into possible legal framework to regulate space traffic and improve the global sharing of space situational awareness, so that space technologies can serve and enhance human well-being in a wider, deeper and higher level. This will in turn bring peace and harmony to humankind and betterment of their life.
* Henry Cheng Professor in International Law and Head of the Department of Law, The University of Hong Kong.
Centre for Aviation and Space Laws 