Towards a Recognised System for Space Traffic Management. A Political-Legal Assessment of the European Contribution to Securing Sustainable Space Activities

Table of Contents

List of abbreviations

Table of authorities

Abstract

1. Introduction
1.1. A picture of outer space – the threat of a system's collapse
1.2. Research questions, purpose, and approach
1.3. Relevance and impact
1.4. State of the art and references

2. Space Traffic Management – an overview
2.1. Findings from the International Academy of Astronautics Cosmic Studies on Spac e Traffic Management
2.2.Contents of Space Traffic Management
2.2.1. Space Situational Awareness as an important element of Space Traffic Management
2.2.2. Sharing of information/data collection on Space Situational Awareness, notification system, and real-time collision avoidance
2.2.3. Traffic rules
2.2.4 . Mechanism for implementation and control
2.2.5 . Space Debris Mitigation
2.3. United States and the JSpOC already providing a de-facto form of Space Traffic Management

3. International, national, and European governance over space activities
3.1 . The question of sovereignty
3.2 . Space as a multilevel governance system
3.3 . First governance triangle – EU, ESA and Member States
3.4 . The EU-ESA relationship
3.4.1 . Cooperation between EU and ESA
3.4.2 . European Space Operations Centre
3.5 . Second governance triangle – EU, ESA and UN

4. EU competences and objectives in the field of Space Traffic Management
4.1 . EU objectives from international law
4.2. EU competences from EU law
4.2.1 . Arts. 4 III, 189 TFEU (Space)
4.2.2 . Arts. 4 II (g), 90 ff. TFEU (Transport)
4.3. EU and Space Traffic Management

5. European activities and capabilities in the field of Space Traffic Management
5.1. European Space Policy
5.2. Code of Conduct for Outer Space Activities
5.3. European Code of Conduct for Space Debris Mitigation
5.4. Space Situational Awareness programme
5.5. Space Surveillance and Tracking Support Framework
5.6. European Union Satellite Centre
5.7. Clean Space Initiative
5.8 . The national States

6. Europe's particular significance in the field of Space Traffic Management

7. Conclusion and Outlook

List of References

Annex
i . Figures and charts
ii. Reply of the European Commission regarding STM-enquiry

Erklärung § 8 Abs. 6 RPO Bachelor

List of abbreviations

Abbildung in dieser Leseprobe nicht enthalten

Table of authorities

- Ch i cag o Convention on International Civil Aviation, entered into force 05 Apr 1947, [hereinafter Chicago Convention].
- Conven ti o n for the establishment of a European Space Agency, entered into force 30 Oct 1980, [hereinafter ESA Convention].
- C onventio n on International Liability for Damage Caused by Space Objects, entered into force 09 Oct 1973, [hereinafter LIAB].
- Conven ti o n on Registration of Objects Launched into Outer Space, entered into force 15 Sept 1976, [hereinafter REG].
- Fra m ewor k Agreement between the European Community and the European Space Agency, entered into force 28 May 2004, [hereinafter EU-ESA Framework Agreement].
- Treat y on European Union, entered into force 01 Dec 2009, [hereinafter TEU].
- Treat y on Principles Governing the Activities of States in the Exploration and Use of Oute r Space, Including the Moon and Other Celestial Bodies, entered into force 10 Oct 1967, [hereinafter OST].
- Trea t y on the Functioning of the European Union, entered into force 01 Dec 2009, [hereinafter TFEU].

"I n order for us to have a future that's exciting and inspiring, it has to be one where we're a space-bearing civilization."

- Elon Musk

Abstract

In today’s climate of increased, even uncoordinated activities in outer space, the need for a Space Traffic Management (STM) system should appear without question, yet remains unresolved. Outer space is increasingly becoming more and more congested and contested. The competing situation in outer space increases collision risks in space operations. Due to space debris, safe access into outer space, operations in outer space and return from outer space to earth free from physical or radio-frequency interference will become difficult in the future and endanger the use of outer space as we know it. STM offers a solution to sustainably deal with these challenges. In particular for Europe, which has become highly dependent on space technology and its applications, this matter is of great importance. If the space system collapses, the consequences for Europe's advancement and prosperity would be severe.

This thesis focuses on the research questions whether Europe can legally and technically contribute to STM, how it can contribute and lastly if it should contribute. The first question primarily relates to legal aspects deriving from international and EU law. The second assess European capabilities in the field of STM, while the last question discusses Europe's significance to contribute to STM or if maybe the United Nations (UN) or the national states are more adequate and should contribute solely.

The thesis reaches the conclusion that Europe can legally, but especially technically contribute to upcoming STM in a meaningful way. The European space actors, (the EU, the European Space Agency (ESA), and the Member States) have greatly enhanced their STM- capabilities (particularly in the field of Space Situational Awareness (SSA)). Europe can also legally contribute to STM, although the complex multilevel governance system complicates any comprehensive contribution. The EU is restricted by EU law and international law, but can play a supporting role towards comprehensive STM. The ESA can contribute if it is tasked to do so. Reality shows that the EU is already active in the field of STM, but refrains from any actual managing of space traffic. The ESA and the Member States are actively working towards actual STM on a technical level. If STM is approached top-down, the European States can help shaping STM at UN level. If STM is approached bottom-up, this task will also be primarily up to the national States, but the EU might contribute supportingly as well. Since long-term sustainability in space is a key priority for Europe and its STM- capabilities are increasingly enhanced, Europe is also certainly adequate to contribute to the challenging task that is STM.

1. Introduction

Outer space has become a crucial part of modern human life and bears countless possibilities of mankind's future. While in the past, outer space has been mostly about research and discovery (issues being gravity, planets or the age of the universe), today the focus has shifted a lot towards commercial activities. Not only are we highly reliant on space and the world could not function without the Global Positioning System (GPS), internet and smartphones enabled by satellites, but the future holds a hardly imaginable use, travel and colonisation of outer space, that so far only science-fictionists dared to predict. The current trends of and needs for fast information exchange via satellite systems will increase exponentially in the upcoming information society, industry 4.0 and the big data revolution. At the moment, everything seems possible, however it is imperative that we keep space clean and accessible in order to guarantee the prosperity and advancement of states and humankind.

1.1. A picture of outer space – the threat of a system's collapse

In today’s climate of increased, even uncoordinated activities in outer space, the need for a Space Traffic Management (STM) system should appear without question, yet remains unresolved. Outer space is increasingly becoming more and more congested and contested. The competing situation in outer space increases collision risks in space operations. Due to space debris¹, safe access into outer space, operations in outer space and return from outer space to earth free from physical or radio-frequency interference will become difficult in the future and endanger the use of outer space as we know it. To date, there have been several confirmed, unintentional collisions between a functional satellite and another space object² that have either damaged the satellite or destroyed both objects and created thousands of new pieces of space debris posing a new threat to other space objects. Even though some objects are gradually removed from orbit due to the drag force³, the whole space system is bound to collapse in the near future due to space debris if countermeasures are not taken. STM offers a means to deal with the challenges of an ever-increasing use of outer space. The efforts of technology development to solve this problem have been well developed, but regulatory issues still remain a major challenge. As with other traditional risk‐related issues, the question is all too often focused on the dominant economic interests; the party carrying the residual risks has, until recently, not been part of the general enquiry. With outer space, the economics of ensuring long-term sustainability are finite, unless players are required to assume an economic share of the responsibility for the safety, security, and mobility of generations to come. This has been seen in other natural environments such as the high seas and Antarctica. When new resources are discovered, new technologies are developed and then there are unanticipated consequences, which ultimately lead to the implementation of management and control rules to assure continued safe use of these resources for future generations. The orbit is such a resource⁴ and the international community carries the long- term burden of (non-)sustainability; the state only carries the general top-up risk for supervising its national space activities; the commercial partner will be subject to various degrees of protection. Long-term sustainability and damage in outer space can only be resolved economically, by putting binding "rules of the road" into place. STM is about ensuring the reduction of damage, as well as allocating failure to adhere to acceptable standards. Currently, the outer space framework lacks effective leverage regarding sustainability (debris-control issues during licensing apart). Especially the OST does not prescribe fault for failure to maintain the sustainability of outer space. In the current era of increased in‐orbit transfers, major manoeuvres in outer space, an expanded variety of activities including space tourism, and not least, issues such as assembly in outer space, the question of binding space traffic rules becomes imperative.

The necessary contents of an STM regime have been developed extensively since the early Millennium, but the implementation ('who', 'how', 'when' and 'which model)' still remains an unsolved issue. Europe has come highly dependent on space technology and its applications⁵ and the European Union (EU) has ever-increasingly become a major space actor, enabled by the European Space Agency (ESA). However the EU lacks certain competences to be a fully recognized public space actor and it also lacks the competences and capabilities to track and detect satellites and space debris like the US are able to. Generally, the European competences and capabilities in the field of STM remain yet to be fully clarified. But long-term sustainability in outer space has to be achieved before the current space system collapses, which would endanger Europe's advancement and prosperity dramatically.

1.2. Research questions, purpose, and approach

This thesis focuses on the research questions whether Europe can legally and technically contribute to STM, how it can contribute and lastly if it should contribute. The first question primarily relates to legal aspects deriving from international and EU law. The second assess European capabilities in the field of STM, while the last question discusses Europe's significance to contribute to STM or if maybe the United Nations (UN) or the national states are more adequate and should contribute solely.

The thesis is meant to give a politico-legal assessment of the European contribution to securing sustainable space activities in the context of upcoming STM. This work is designed to contribute to a transition in the debate from the question of 'who' to 'how' to ensure sustainability for outer space activities and to provide some specific input to existing capabilities and mechanisms for harmonized control, enforcement and operative oversight over space traffic.

In order to answer its research questions, this thesis begins with an overview over STM, outlining recent findings and its contents. The next step is to look at the international, national and European governance over space activities. In this part, the difficult question of sovereignty in outer space is explored and space is depicted as a multilevel governance system where the UN, EU, ESA and their Member States all have (sometimes overlapping) competences and interests. Subsequently, the EU competences and objectives from international and EU law are analysed, and then the particularities of EU competences in the field of STM are reviewed. Afterwards, the thesis discusses the different European activities and capabilities in the field of STM. In the final part of the thesis, Europe's adequacy to contribute to STM will be discussed.

1.3. Relevance and impact

Outer space has become an immanent part of modern human life, in which scientific, economical and judicial progress is developing rapidly and dynamically. As space debris is becoming increasingly a challenging issue, threatening past achievements and the further use of outer space, mankind has to look for solutions. STM is accepted as one possible answer to the problem of a congested outer space, but it could not be implemented for different reasons so far.

If Europe truly wants to keep its leading role in space and modern society wishes to continue enjoying the benefits of outer space, countermeasures or a means to deal with an increasingly congested orbit have to be implemented quickly. For Europe, comprehensive STM offers a promising means to ensure long-term sustainability in outer space and to safeguard a prosperous future.

1.4. State of the art and references

There is barely any research on the subject of the European contribution to STM. Legal and technical contents of STM, space governance and Europe's space activities and capabilities have been extensively analysed and reviewed so far, but the academic link is lacking to date.

This thesis refers to various primary and secondary sources. Primary references comprehend reports, resolutions, communications, agreements, treaties, conventions, etc. from the different international, national and European space actors regarding a wide range of issues relating to STM and European space competences, activities and capabilities that relate to this field. Secondary references are academic papers and books relating to the same topics. As stated before, the issues of STM and European space activities have been researched in detail, but there is barely any research on Europe's contribution towards comprehensive STM. Therefore, the thesis can only refer to sources that underline its argument and assessment.

2. Space Traffic Management – an overview

STM is defined 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."⁶ This premises and requires policies, regulations, services and information exchange. As the number of space actors and objects is ever- increasing and international space law is inadequate to meet the challenges of overcrowded orbits thus far, the idea emerged to regulate space activities with a comprehensive traffic regime that comprises the launch phase, the in-orbit operation phase, and the re-entry phase. Regulating these phases requires space-related norms, object related norms, and traffic-related norms.⁷

STM is generally understood as measures taken to minimize or mitigate the negative impacts (through regulations and technical measures) of the current and increasing congested⁸, contested ⁹ and competing ¹⁰ situation of outer space. With currently more than 750,000 objects larger than 1 cm in orbit in outer space, of which the US military is only able to track approximately 23,000 larger than 10 cm at the moment¹¹, these objects pose a collision risk¹² to the about 1,200¹³ operating satellites and manned systems¹⁴ and dramatically increase the costs of space operations.¹⁵ The typical velocity of these objects is 30.000 km per hour¹⁶ or more. There have been already several confirmed, unintentional collisions between functional satellites and space debris which have either damaged or destroyed the involved space objects and thereby caused new space debris.¹⁷ The untimely termination of an active satellite's mission can cost the owner (or his insurance provider) potentially millions of dollars in losses.¹⁸ STM aims at eliminating future collisions and other incidents in outer space which could cause additional debris or cause potential safety risks for space activities or to persons and infrastructure in space or on earth, increasing the safety, efficiency and sustainably of these activities.

Currently, there is no widespread state practice or established international regime with regard to STM. No one is responsible under international law (cf. the question of sovereignty, 3.1.) for the creation of "rules of the road" in outer space. STM is not conceptually established in the space treaties.¹⁹ However, core elements of STM like liability, registration and information exchange are regulated in current international space law,²⁰ and national space legislation and soft law contain scattered elements of STM. The debate is ongoing over whether an international STM regime should begin with national practice or an international treaty. There are also comparisons between STM and Air Traffic Management (ATM) and proposals for a new treaty to establish an international body similar to the International Civil Aviation Organization (ICAO), which sets standards for STM. However, outer space is too different from air space for comparison, from a legal point of view especially with regard to sovereignty (cf. 3.1.).

STM is considered an essential and fundamental task to ensure safety and sustainability in space activities, which guarantees that societal demands today and in the future are met.²¹ It holds the potential to tie existing technologies, infrastructures and legal instruments together.²² STM could provide for a systematic and coordinated approach to ensure long- term sustainability in outer space and guarantee the continued use of space free from harmful or unwanted interference for the benefit of mankind.

2.1. Findings from the International Academy of Astronautics Cosmic Studies on Spac e Traffic Management

The two International Academy of Astronautics (I AA) Cosmic Studies are the central academic analyses of STM. The 2006 study provides the first comprehensive approach to STM, identifying the problems and perspectives for future STM and laying down the important groundwork for the following academic discourse and the 2016 IAA Cosmic Study. Contents and notions of the 2006 study and its academic reception are processed in this thesis when reviewing STM (cf. section 2.). The 2016 IAA Cosmic Study brings both many proposals and open questions on the issue of STM. The study distinguishes between technical and regulatory STM. The debate is ongoing over whether an international STM regime should be established via national practice and a gradual bottom-up approach or if an international treaty regulating STM through a comprehensive top-down approach is the right way to go. ²³ The first needs national regulation and development of Space Situational Awareness (SSA), private human spaceflight, debris mitigation and remediation, developments of standards for space safety, traffic rules, practices for the management of space resources, national space legislation, and organisational aspects. The second requires a fundament for a comprehensive STM regime with an overarching institutional frame relying on existing international law, domestic legislation, diplomatic initiatives and common technical standards for spaceflight. Elements of the incremental bottom-up approach are already in place today and establishing STM this way seems less challenging. However, the top-down approach presents the opportunity to achieve a coherent end-to-end framework, but the elements are not yet covered. Due to the complex, international institutional setting, the second approach appears more challenging. Ultimately, questions of governance and sovereignty remain to be answered. Both approaches have in common that common traffic management rules, a notification system for collision avoidance, information and data sharing and dispute settlement are imperative.²⁴ Considering the States' unwillingness to adopt legally binding rules in the current space setting, the bottom-up approach is considered unlikely to evolve to adequately tackle the challenges of STM.²⁵ It has also been proposed to establish a new treaty and an international body setting standards for STM similar to ATM.²⁶ In the end, establishing an international regulatory STM framework either way depends foremost on the political will. ²⁷ Only then will it be possible to guarantee long-term sustainability in outer space.

2.2. Contents of Space Traffic Management

STM comprises primarily four elements (plus Space Debris Mitigation (SDM) is also considered in this context): Securing the information needs (SSA, information/data collection and sharing), a notification system for collision avoidance, concrete traffic rules, and mechanisms for implementation and control. These elements will be briefly reviewed subsequently (cf. 2.2.1.-2.2.5.) and later compared to the European contribution (cf. section 5.).

2.2.1. Space Situational Awareness as an important element of Space Traffic Management

SSA is an important element and considered a prerequisite for STM.²⁸ SSA refers to the capability to watch for objects and natural phenomena that could harm satellites in orbit or even infrastructure on the ground. SSA helps understanding and maintaining awareness of the Earth's orbital population, the space environment and possible threats and risks that could arise. ²⁹ The operational way of reaching SSA is via Space Surveillance. Space Surveillance is considered as the "rout ine operational service of timely detection, correlation, characterisation, and orbit determination of space objects."³⁰ By contrast, SSA then refers more to data processing and use.³¹ At the moment, SSA information is already provided by several space agencies (for example Russia, China, France, Germany, Norway, or the ESA),³² but the most complete catalogue of space objects is provided by the US Department of Defense via the Joint Space Operations Center (JSpOC) (cf. 2.3.). Despite its well- developed technical capabilities, even the JSpOC and all the other space agencies are only able to track and detect objects larger than 10 cm. This is a problematic limit for STM and has to be dealt with in the future, as the amount of objects (many of them smaller than 10 cm, cf. section 2.) in outer space increases. Spacecraft operators need data through tracking and detecting that is as accurate as possible, ³³ in order to have a better situational awareness in space and sufficient information to watch out for potential threats (for example during close approaches), which might affect their operations.³⁴ For any future STM, well- developed SSA capabilities are imperative.

2.2.2. Sharing of information/data collection on Space Situational Awareness, notification system, and real-time collision avoidance

Besides the SSA data collection, there needs to be rules established regarding data provision, the definition of necessary data that has to be shared and data management.³⁵ The ESA (cf. 5.4.) or the JSpOC (cf. 2.3.) are already sharing a lot of their data, but standards that capture rules for sharing SSA data in a timely manner³⁶ in order to avoid potential threats and risks, for evasion manoeuvres, or for impact minimisation have yet to be set.³⁷

For successful STM, a sound information system regarding SSA is required and it has to be accessible to all space actors.³⁸ Such a system or service would need to combine data from multiple sources, like tracking resources (optical telescopes or radar), computing power, and sophisticated software, to calculate the thousands of possible daily satellite-satellite or satellite-debris conjunctions.³⁹ Currently, only the REG requires notification and data sharing, and its registration system is insufficient for STM. Rather, for STM there need to be comprehensive notification rules and a system for safe launch, in-orbit operation and re- entry.⁴⁰ Collision avoidance is already taking place in space operations,⁴¹ but as the use and congestion of outer space increases, it will no longer be possible to simply forecast and react to impending collisions with adequate advance time,⁴² but necessary to be able to react and manage space operations in real-time.

At this early stage of working towards a recognised system of STM, it remains unclear who would or should provide such a comprehensive service. Since operating and maintaining such a service is expensive,⁴³ it is likely that this will remain a governmental function.

2.2.3. Traffic rules

As any traffic regime, STM needs concrete traffic rules (combined with rules for notification and information, cf. 2.2.2.) and standards for safe launches, space operations and re- entry/post-mission with particular regard to manoeuvres for avoiding interference and predicting approaches, fly zones, and debris mitigation or at least propagating operational and disposal orbits.⁴⁴ These "rules of the road" have yet to be set.⁴⁵

In view of successful STM, it is necessary that operators and governments know who is potentially liable and responsible for space operations.⁴⁶ For this purpose, it is helpful to briefly revisit present liability and responsibility rules of space law. Art. VII OST first introduces the concept of liability in international space law. According to Art. VII OST, launching States⁴⁷ are liable for damages caused by their launched objects or components parts thereof, and thus are obligated to pay compensation to a harmed State Party to the OST or its natural or judicial persons. Art. II LIAB establishes the norm of absolute liability for launching States whose space objects caused damage on the surface of the Earth or to aircraft in flight. This is in contrast to fault-based liability in accordance with Art. III LIAB, which states that “[i] n the event of damage being caused elsewhere ⁴⁸ [.] the launching State [.] shall be liable only if the damage is due to its fault or the fault of persons for whom it is responsible.” Responsibility, according to Art. VIOST, is the duty of the State Parties to the OST to control their respective national activities (whether carried out by governmental agencies or non-governmental entities), but also International Organisations (IOs) in which they are participating. According to Art. VIII OST, a State Party to the OST, on whose registry an object launched into outer space is carried, retains jurisdiction and control over said object in outer space. Registration (especially through the REG) so far is established in the international space law system and a prerequisite for jurisdiction and control. However, traffic information (cf. 2.2.2.) is not yet generally provided, but needed for space safety, security and sustainability.⁴⁹ Liability and responsibility rules in international space law are insufficient for current space developments and need to be reworked for STM. For example it is often impossible to prove that a certain object or component part that has caused damage to another space object belongs or has belonged to a certain State, if the responsible object or part was previously not being tracked or detected. Enforcing liability then also becomes impossible. It would be necessary to have an international catalogue of space objects, owners, operators and mission-specific information in order to be able to enforce these rules.⁵⁰ Furthermore, current liability and responsibility rules in space law have a particular inter-State focus. As private actors become increasingly active in outer space, these rules appear out-dated. Another problem with current liability rules is that space objects⁵¹ remain under the launching State's control post-mission, with the result that the launching State would need to give permission (or transfer ownership) and transfer liability before its space object could be removed,⁵² hindering active debris removal efforts. Also, if damages occur not on Earth or to aircraft in flight, according to Art. III LIAB it must be due to fault (which – again – is difficult to prove). Yet without traffic rules, there is no fault liability.⁵³ This further underlines the need to rework liability rules in space law for which STM provides a good opportunity.

2.2.4. Mechanism for implementation and control

Like any other legal regime, STM would need mechanisms for implementation and control. Currently, this is still under discussion and not conclusively developed. To date, enforcement or inspection mechanisms (if at all) remain within the jurisdiction of the national States. For successful STM, this has to change. The 2016 IAA Cosmic Study on STM (cf. 2.1.) proposes a mechanism for the settlement of disputes to enforce space traffic rules by treaty provision.⁵⁴

2.2.5. Space Debris Mitigation

Another important aspect of STM are the space sustainability-related SDM-efforts. This refers to measures taken to create less or even remove space debris, to choose orbits with less risk of collision (preventing that more debris results from collisions, cf. section 2.), in general to prevent collisions that can cause (more) debris, to release less mission-related debris in space operations, and to sustainably handle end-of-life disposal and re-entry of space objects.⁵⁵ In a fragile environment like space, where space objects and debris are ever increasing, these measures are imperatively required. Space actors who are contributing to mitigating space debris play an important role in preserving (the use of) space for future generations.

2.3. United States and the JSpOC already providing a de-facto form of Space Traffic Management

In 2009, after the collision of Iridium 33 and Cosmos 2251 ⁵⁶ , the US initiated a program to monitor global space traffic and provide close-approach warnings for satellite operators around the globe. The US Space Surveillance Network (SSN) tracks, detects, identifies and catalogues all manmade objects orbiting the earth, ⁵⁷ which are bigger than 10 cm (approximately 23,000 at the moment⁵⁸ ).⁵⁹ This program executed by the US military through the JSpOC is sometimes seen as a de-facto form of STM.⁶⁰ Today, only the US fully possess the capability to watch for objects in space. While approaching global STM, other spacefaring nations need to improve their SSA capabilities.

3. International, national, and European governance over space activities

Space governance is as complex as it is not conclusively developed. Nevertheless, it is important to review what has been established so far and what might be relevant when it comes to STM in general, but especially in the context of the European contribution. For this reason, the issue of sovereignty in space will be picked up once again as it is one of the main obstacles for establishing a comprehensive STM regime. Furthermore, the multilevel governance system will be described as it affects all collective European space activities.

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¹ Viikari, 2008: 31-45.

² Ailor, 2015: 234-235.

³ Ailor, 2015: 233.

⁴ Ailor, 2015: 244.

⁵ Rathgeber, 2008: 4.

⁶ Contant-Jorgenson, Lála and Schrogl, 2006: 10.

⁷ Soucek, 2016a: 12.

⁸ Constantly growing number of space operators and countries owing space assets, constantly growing space debris.

⁹ Dependence on space-based systems has increased enormously, but also their vulnerability due to development of new offensive capabilities.

¹⁰ Commercial space operators are increasingly driving competition for higher performance and lower cost space systems.

¹¹ Masson-Zwaan, 2017: 33.

¹² ESA: Space Debris: Assessing the Risk.

¹³ Numbers provided by the ESA's Space Debris Office at ESOC, correct as of January 2017, available via: http://www.esa.int/Our_Activities/Operations/Space_Debris/Space_debris_by_the_numbers.

¹⁴ Ailor and Krag, 2009: 261.

¹⁵ Ailor, Womack, Peterson and Murrell, 2010: 1.

¹⁶ In the event of collision, more crucial than mass (m) is in fact the object's velocity (v) for the force of the impact (Kinetic energy = ½ m v 2). This means that even a small object at a high velocity can cause high damage, which is exactly the case with debris in orbit. An object of 1 cm moving at 10 km per second has an impact energy comparable to the explosive force of a hand grenade.

¹⁷ Masson-Zwaan, 2017:40.

¹⁸ Ailor, 2010: 123.

¹⁹ Soucek, 2016a: 6.

²⁰ Soucek, 2016a: 6.

²¹ Schrogl, 2011: 609.

²² Schrogl, Jorgenson, Robinson and Soucek, 2016: 120.

²³ Schrogl, Jorgenson, Robinson and Soucek, 2016: 14.

²⁴ Schrogl, Jorgenson, Robinson and Soucek, 2016: 14-17.

²⁵ Schrogl, Jorgenson, Robinson and Soucek, 2016: 15.

²⁶ Schrogl, Jorgenson, Robinson and Soucek, 2016: 22.

²⁷ Schrogl, Jorgenson, Robinson and Soucek, 2016: 14.

²⁸ Schrogl, Jorgenson, Robinson and Soucek, 2016: 79.

²⁹ Schrogl, 2011: 607.

³⁰ Rathgeber, 2008: 7.

³¹ Del Monte, 2007: 2.

³² Williamson, 2010: 14.

³³ Ailor, 2010: 127.

³⁴ Williamson, 2010: 14.

³⁵ Schrogl, 2007: 3.

³⁶ Ailor, 2010: 126.

³⁷ Ailor, 2015: 246.

³⁸ Schrogl, 2007: 3.

³⁹ Williamson, 2010: 14.

⁴⁰ Schrogl, 2007: 3.

⁴¹ Ailor, 2015: 237.

⁴² Ailor, 2015: 245.

⁴³ Wyler, 2017: 109.

⁴⁴ Schrogl, 2007: 3.

⁴⁵ Ailor, 2015: 246.

⁴⁶ Ailor, 2015: 246.

⁴⁷ Launching States are states who launch, procure a launch or from whose territory or facility is launched. An equivalent definition is used in Art. I LIAB.

⁴⁸ Not on Earth or to aircraft in flight as in Art. II LIAB.

⁴⁹ Schmidt-Tedd, 2017: 69.

⁵⁰ Ailor, 2015: 246.

⁵¹ Which can be all manmade objects in space, from functioning satellites to debris.

⁵² Ailor, 2015: 252.

⁵³ Schmidt-Tedd, 2017: 67.

⁵⁴ Schrogl, Jorgenson, Robinson and Soucek: 2016: 115.

⁵⁵ Space Safety Magazine: 2014.

⁵⁶ After the collision, space debris drastically increased, cf. annex i. 2).

⁵⁷ Alby, 2013: 412.

⁵⁸ Masson-Zwaan, 2017: 33.

⁵⁹ Ailor, 2015: 245.

⁶⁰ Sgobba, 2016: 3.