- Email: [email protected]
Space debris and the need for space traffic control
Space Policy xxx (2013) 1e3
Contents lists available at ScienceDirect
Space Policy journal homepage: www.elsevier.com/locate/spacepol
Report
Space debris and the need for space traffic control Phillip A. Slann* Keele University, Newcastle-under-Lyme, ST5 5BG, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Article history: Received 4 September 2013 Accepted 29 October 2013 Available online xxx
This report summarises the presentations which took place at the ‘Space Traffic Control e Is the Space Debris Problem Solvable?’ conference hosted by the Royal Aeronautical Society on the 2nd July 2013. The conference sought to promote discussion over methods to deal with the issue of space debris in particular and speakers included representatives from the European Space Agency, the United Kingdom Space Agency, practitioners and academia. Themes which emerged during the conference included the urgency of the problem of space debris, the need for short-term and long-term solutions, the necessity for the development and implementation of space debris remediation technologies to complement existing mitigation efforts and, last but not least, the wider applications of space traffic control. Regarding the sub-title of the conference, ‘is the space debris problem solvable?’, it would appear from the presentations that while there is the potential for future management of the issue through debris remediation and harmonised mitigation efforts, no comprehensive solutions exist at the time of writing. Ó 2013 Elsevier Ltd. All rights reserved.
Keywords: Space debris Space traffic control
1. Introduction Terrestrial societies are becoming increasingly dependent upon satellites for the provision of services used every day in both civilian and military walks of life, such as communications, meteorological data and remote sensing. This dependence requires careful attention to risks and dangers which threaten to disrupt the operation of activities in outer space. The ‘Space Traffic Control e Is the Space Debris Problem Solvable?’ conference, hosted by the Royal Aeronautical Society on the 2nd July 2013, sought to promote discussion over methods to deal with the issue of space debris in particular. Speakers included representatives from ESA,1 the UKSA, practitioners and academia. 2. The issue at hand: space debris The conference began with an introduction to the problem at hand by Professor Heiner Klinkrad of ESA. He estimated that the existing space debris population is around 7000 tonnes of man* Tel.: þ44 (0)7795466881. E-mail address: [email protected]. 1 This report uses the following abbreviations: European Space Agency (ESA), Inter-Agency Space Debris Coordination Committee (IADC), Lower Earth Orbit (LEO), Geosynchronous Orbit (GEO), Geostationary Orbit (GSO), Outer Space Treaty (OST), Space Situational Awareness (SSA), Surrey Satellite Technology (SSTL), United Kingdom Space Agency (UKSA) and United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS).
made objects orbiting the Earth, the vast majority of which is made up of objects larger than 10 cm. Objects of this size can be tracked and catalogued by existing SSA capabilities and it is estimated that there are around 23,000 objects within the catalogue maintained by the United States Space Surveillance Network. Of these 23,000 objects, a figure which includes active satellites and debris, information concerning 17,000 is publicly available. The remaining 6000 objects are ones about which the origin is unknown or the data remains confidential. As debris smaller than 10 cm cannot be tracked and catalogued, there is less certainty about the extent of the debris population, however it is estimated that there is around 740,000 pieces of debris in orbit between 1 and 10 cm in size. Professor Klinkrad pointed out however that it is believed that debris in this size range only constitute 50 tonnes of mass together. Nonetheless, as Professor Richard Crowther of the UKSA highlighted later on in the day, debris between 1 and 10 cm is a great concern for satellite operators, as it is too big to be shielded against but too small to be catalogued and tracked. It is estimated that there is around 170,000,000 pieces of debris in orbit smaller than 1 cm, and an object 1 mm in size has the potential to damage satellite sub-systems or pierce an astronaut’s protective suit. Numerous examples were brought up throughout the day of Collision Avoidance Manoeuvres and damage caused by conjunction events, highlighting the fact that space debris is already a threat to satellite operations, particularly in LEO at around 800 km in altitude, where the majority of remote sensing satellites operate from.
0265-9646/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.spacepol.2013.10.007
Please cite this article in press as: Slann PA, Space debris and the need for space traffic control, Space Policy (2013), http://dx.doi.org/10.1016/ j.spacepol.2013.10.007
2
P.A. Slann / Space Policy xxx (2013) 1e3
3. Perspectives on space debris
5. Space debris remediation
Following Professor Klinkrad’s introduction, Philip Crystal provided an overview of insurer’s perceptions of space debris. Satellite insurance often covers three stages; launch, post-separation/inorbit testing and in-orbit operations and the vast majority of insured satellites, worth a total value of about $18.3 billion, are operating in GEO/GSO. As the debris situation in this region is not yet as serious as in LEO, Mr. Crystal noted that many insurers perceive space debris to be a manageable risk rather than an urgent problem, although they do appreciate the danger to satellites in both LEO and GEO/GSO. He also speculated that space weather and technical malfunctions may well be considered more significant risks by insurers. Nonetheless, there appears to be widespread agreement amongst insurers that the current legal regime concerning outer space activities is insufficient, a topic which was discussed in more detail by the following speaker, Joanne Wheeler LLM. Ms. Wheeler outlined the legal perspective on space debris and began by introducing existing space law, including what she termed the ‘Magna Carta’ of space law: the 1967 OST. In terms of space debris, although the OST does not specifically mention the issue, some of its provisions can be applied. These include the responsibility of parties to conduct activities ‘with due regard to the corresponding interests of all other States Parties to the Treaty’ and the responsibility to ensure that any exploration ‘of outer space, including the Moon and other celestial bodies’ is undertaken in a manner ‘so as to avoid their harmful contamination’ [1]. Ms. Wheeler then outlined how existing space law is applied in practice. As per the provisions of Article III of the 1972 Liability Convention, in order to prove that a party can be deemed liable for a collision between two space objects in outer space, the other would have to conclusively establish that one of the launching states, or persons for whom it is responsible, is at fault. The complexities involved with establishing liability are due in no small part to a number of legal difficulties with regards to space debris; namely that there are no definitions of what constitutes space objects and space debris, while demonstrating the causality of any damage is not a simple affair, particularly when particulate space debris is involved. Moreover, the need to identify the party responsible for any offending space debris and then proving fault complicates the matter further, even more so in the absence of any mandatory international standards for assessing fault.
There was a consensus amongst those presenting that space debris remediation is urgently required; Professor Klinkrad estimated that cascading debris generation, otherwise referred to as the Kessler Syndrome, will begin within the next twenty years unless action is taken to reduce the existing population. He noted that in order to avoid the onset of the Kessler Syndrome, large space objects e such as satellites or rocket bodies e need to be de-orbited or re-orbited at a rate of ten to fifteen per year. However, such actions are both unprecedented and technically difficult, not least because of the variety of shapes and sizes of debris in orbit. Moreover, Ms. Wheeler pointed out some of the legal issues surrounding space debris remediation; in particular she elaborated on the need to establish ownership over any space objects which are the focus of remediation efforts, as under international law permission would be required before any interference could take place with those objects. Other legal issues included concerns regarding intellectual property, liability over the remediated debris and the surveillance capabilities of debris remediation programmes. Luisa Innocenti outlined the debris remediation segment of the Clean Space Initiative, which has the objective of developing technologies to enable the capturing and de-orbiting or re-orbiting of space debris. She explained that ESA is looking to undertake a mission by 2022 to de-orbit one of their inactive satellites. Given the legal complexities associated with space debris remediation, ESA has decided to de-orbit one of its satellites rather than seek permission from another actor. Dr. Jaime Reed then introduced two methods of space debris remediation being developed and studied by Astrium; a net and a harpoon system designed to enable the de-orbiting or reorbiting of space objects. The net system was first developed as a concept in 2003, and demonstrations have indicated its potential as a space debris remediation technology. The harpoon system meanwhile is intended to be compatible with a multitude of targets with varying shapes and sizes and is designed to avoid the generation of debris during usage. Although both the net and harpoon systems are still in the relatively early stages of development, the underlying objective behind them is the introduction of low-cost re-useable space debris remediation technologies. With respect to drag-augmentation systems, Charlotte Bewick from OHB System AG presented research on the collision risks associated with deployment of such systems. She argued that whilst such methods have the capability to dramatically increase the speed with which small objects can be de-orbited, their use with regards to objects at altitudes of 800 km and above would introduce such significant risks of collision with other objects to negate the advantages of the accelerated de-orbiting. Turning to on-going research and development within the field of drag-augmentation systems, Vaios Lappas of the University of Surrey introduced a number of projects being developed for the purposes of debris remediation, including the CubeSail and DeorbitSail projects. These projects are designed demonstrate the capability of drag-augmentation systems to de-orbit space debris quickly and efficiently. The projects are undergoing testing on Earth at the moment, with a view to in-orbit testing commencing in the near future.
4. Space debris mitigation Space debris mitigation was discussed in a number of presentations though there were none dedicated specifically to it. Ms. Wheeler provided an overview a few of the existing national and international space debris mitigation guidelines, including the IADC Draft Space Debris Mitigation Guidelines, the Space Debris Mitigation Guidelines of the Scientific and Technical Subcommittee of UNCOPUOS, the European Code of Conduct for Space Debris Mitigation and the ESA Space Debris Mitigation Handbook. Although these guidelines are all non-binding recommendations, they are indicative of agreed-upon best practices for space debris mitigation. Nonetheless, Ms. Wheeler argued that international mitigation measures must be harmonised to avoid unfair competition. Luisa Innocenti of ESA also discussed the space debris mitigation measures associated with ESA’s Clean Space Initiative, which she described as a roadmap of technologies directed at environmental sustainability both on Earth and in orbit. These include technologies to ensure that ESA missions meet debris mitigation requirements, with an emphasis on post-operation passivation and disposal through de-orbiting and re-orbiting.
6. Space traffic control While the main conference title was Space Traffic Control, the event prioritised space debris over other possible associated themes. Professor Crowther contended during his presentation on best practice initiatives that space is becoming more ‘congested,
Please cite this article in press as: Slann PA, Space debris and the need for space traffic control, Space Policy (2013), http://dx.doi.org/10.1016/ j.spacepol.2013.10.007
P.A. Slann / Space Policy xxx (2013) 1e3
contested and competed’ and thus there needs to be an increased focus upon ‘safety, security and sustainability’. He outlined current and possible future forms of governance with regards to outer space affairs, including the International Telecommunications Union’s regulation of the radio-frequency spectrum and orbital resources, as well as the work of UNCOPUOS and, finally, Transparency and Confidence-Building Measures. Taking the UK as an example, Professor Crowther detailed the regulation process for space missions falling under the responsibility of the UK government, explaining that the Secretary of State requires licensees to operate in a manner that will prevent contamination of outer space, avoid adverse changes to the terrestrial environment and not interfere with the extra-terrestrial operations of other actors. Professor Crowther also discussed the need for governance of space debris remediation efforts, noting that although some systems show promise, their potential for misuse must be taken into account and mitigated. Concluding the conference, Dr. Stuart Eves of SSTL expanded on the other areas to which space traffic control may be applied, including improved space weather and solar monitoring, enhanced tracking of both debris and active satellites, notification of fragmentation events, prediction of re-entry events, conjunction predictions and warnings and notification of manoeuvres. Dr. Eves also commented on the need for improved frequency coordination, noting that this will be crucial given the expected future growth in the number of manned space missions, combined with the likelihood that some vehicles will be transitioning between air traffic and outer space traffic control standards.
3
7. Conclusions Four themes emerged during the conference; firstly that space debris is an urgent problem requiring both short-term and long-term solutions. Secondly, that space debris mitigation efforts can only go so far and thus the development and implementation of remediation technologies is necessary to prevent the onset of cascading debris generation. The third theme concerned the governance of space debris remediation efforts; there needs to be clearer legal guidance regarding liabilities and responsibilities, as well as transparency to ensure that remediation technologies are not misused or perceived as threats to other spacefaring actors. Finally, the fourth theme indicated that space traffic control extends beyond space debris to issues over frequency regulation, space weather and station-keeping manoeuvres. Whilst the conference was dedicated to space debris, a number of the presentations highlighted the need for further discussions of the wider applications of space traffic control. Regarding the sub-title of the conference, ‘is the space debris problem solvable?’, it would appear from the presentations that while there is the potential for future management of the issue through debris remediation and harmonised mitigation efforts, no comprehensive solutions exist at the time of writing. Reference [1] United Nations. United Nations Treaties and Principles on Outer Space Text of treaties and principles governing the activities of States in the exploration and use of outer space, adopted by the United Nations General Assembly, ST/SPACE/ 11, New York: United Nations, available from: http://www.unoosa.org/pdf/ publications/STSPACE11E.pdf. p. 6, [last accessed 03.09.13].
Please cite this article in press as: Slann PA, Space debris and the need for space traffic control, Space Policy (2013), http://dx.doi.org/10.1016/ j.spacepol.2013.10.007
Contents lists available at ScienceDirect
Space Policy journal homepage: www.elsevier.com/locate/spacepol
Report
Space debris and the need for space traffic control Phillip A. Slann* Keele University, Newcastle-under-Lyme, ST5 5BG, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Article history: Received 4 September 2013 Accepted 29 October 2013 Available online xxx
This report summarises the presentations which took place at the ‘Space Traffic Control e Is the Space Debris Problem Solvable?’ conference hosted by the Royal Aeronautical Society on the 2nd July 2013. The conference sought to promote discussion over methods to deal with the issue of space debris in particular and speakers included representatives from the European Space Agency, the United Kingdom Space Agency, practitioners and academia. Themes which emerged during the conference included the urgency of the problem of space debris, the need for short-term and long-term solutions, the necessity for the development and implementation of space debris remediation technologies to complement existing mitigation efforts and, last but not least, the wider applications of space traffic control. Regarding the sub-title of the conference, ‘is the space debris problem solvable?’, it would appear from the presentations that while there is the potential for future management of the issue through debris remediation and harmonised mitigation efforts, no comprehensive solutions exist at the time of writing. Ó 2013 Elsevier Ltd. All rights reserved.
Keywords: Space debris Space traffic control
1. Introduction Terrestrial societies are becoming increasingly dependent upon satellites for the provision of services used every day in both civilian and military walks of life, such as communications, meteorological data and remote sensing. This dependence requires careful attention to risks and dangers which threaten to disrupt the operation of activities in outer space. The ‘Space Traffic Control e Is the Space Debris Problem Solvable?’ conference, hosted by the Royal Aeronautical Society on the 2nd July 2013, sought to promote discussion over methods to deal with the issue of space debris in particular. Speakers included representatives from ESA,1 the UKSA, practitioners and academia. 2. The issue at hand: space debris The conference began with an introduction to the problem at hand by Professor Heiner Klinkrad of ESA. He estimated that the existing space debris population is around 7000 tonnes of man* Tel.: þ44 (0)7795466881. E-mail address: [email protected]. 1 This report uses the following abbreviations: European Space Agency (ESA), Inter-Agency Space Debris Coordination Committee (IADC), Lower Earth Orbit (LEO), Geosynchronous Orbit (GEO), Geostationary Orbit (GSO), Outer Space Treaty (OST), Space Situational Awareness (SSA), Surrey Satellite Technology (SSTL), United Kingdom Space Agency (UKSA) and United Nations Committee on the Peaceful Uses of Outer Space (UNCOPUOS).
made objects orbiting the Earth, the vast majority of which is made up of objects larger than 10 cm. Objects of this size can be tracked and catalogued by existing SSA capabilities and it is estimated that there are around 23,000 objects within the catalogue maintained by the United States Space Surveillance Network. Of these 23,000 objects, a figure which includes active satellites and debris, information concerning 17,000 is publicly available. The remaining 6000 objects are ones about which the origin is unknown or the data remains confidential. As debris smaller than 10 cm cannot be tracked and catalogued, there is less certainty about the extent of the debris population, however it is estimated that there is around 740,000 pieces of debris in orbit between 1 and 10 cm in size. Professor Klinkrad pointed out however that it is believed that debris in this size range only constitute 50 tonnes of mass together. Nonetheless, as Professor Richard Crowther of the UKSA highlighted later on in the day, debris between 1 and 10 cm is a great concern for satellite operators, as it is too big to be shielded against but too small to be catalogued and tracked. It is estimated that there is around 170,000,000 pieces of debris in orbit smaller than 1 cm, and an object 1 mm in size has the potential to damage satellite sub-systems or pierce an astronaut’s protective suit. Numerous examples were brought up throughout the day of Collision Avoidance Manoeuvres and damage caused by conjunction events, highlighting the fact that space debris is already a threat to satellite operations, particularly in LEO at around 800 km in altitude, where the majority of remote sensing satellites operate from.
0265-9646/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.spacepol.2013.10.007
Please cite this article in press as: Slann PA, Space debris and the need for space traffic control, Space Policy (2013), http://dx.doi.org/10.1016/ j.spacepol.2013.10.007
2
P.A. Slann / Space Policy xxx (2013) 1e3
3. Perspectives on space debris
5. Space debris remediation
Following Professor Klinkrad’s introduction, Philip Crystal provided an overview of insurer’s perceptions of space debris. Satellite insurance often covers three stages; launch, post-separation/inorbit testing and in-orbit operations and the vast majority of insured satellites, worth a total value of about $18.3 billion, are operating in GEO/GSO. As the debris situation in this region is not yet as serious as in LEO, Mr. Crystal noted that many insurers perceive space debris to be a manageable risk rather than an urgent problem, although they do appreciate the danger to satellites in both LEO and GEO/GSO. He also speculated that space weather and technical malfunctions may well be considered more significant risks by insurers. Nonetheless, there appears to be widespread agreement amongst insurers that the current legal regime concerning outer space activities is insufficient, a topic which was discussed in more detail by the following speaker, Joanne Wheeler LLM. Ms. Wheeler outlined the legal perspective on space debris and began by introducing existing space law, including what she termed the ‘Magna Carta’ of space law: the 1967 OST. In terms of space debris, although the OST does not specifically mention the issue, some of its provisions can be applied. These include the responsibility of parties to conduct activities ‘with due regard to the corresponding interests of all other States Parties to the Treaty’ and the responsibility to ensure that any exploration ‘of outer space, including the Moon and other celestial bodies’ is undertaken in a manner ‘so as to avoid their harmful contamination’ [1]. Ms. Wheeler then outlined how existing space law is applied in practice. As per the provisions of Article III of the 1972 Liability Convention, in order to prove that a party can be deemed liable for a collision between two space objects in outer space, the other would have to conclusively establish that one of the launching states, or persons for whom it is responsible, is at fault. The complexities involved with establishing liability are due in no small part to a number of legal difficulties with regards to space debris; namely that there are no definitions of what constitutes space objects and space debris, while demonstrating the causality of any damage is not a simple affair, particularly when particulate space debris is involved. Moreover, the need to identify the party responsible for any offending space debris and then proving fault complicates the matter further, even more so in the absence of any mandatory international standards for assessing fault.
There was a consensus amongst those presenting that space debris remediation is urgently required; Professor Klinkrad estimated that cascading debris generation, otherwise referred to as the Kessler Syndrome, will begin within the next twenty years unless action is taken to reduce the existing population. He noted that in order to avoid the onset of the Kessler Syndrome, large space objects e such as satellites or rocket bodies e need to be de-orbited or re-orbited at a rate of ten to fifteen per year. However, such actions are both unprecedented and technically difficult, not least because of the variety of shapes and sizes of debris in orbit. Moreover, Ms. Wheeler pointed out some of the legal issues surrounding space debris remediation; in particular she elaborated on the need to establish ownership over any space objects which are the focus of remediation efforts, as under international law permission would be required before any interference could take place with those objects. Other legal issues included concerns regarding intellectual property, liability over the remediated debris and the surveillance capabilities of debris remediation programmes. Luisa Innocenti outlined the debris remediation segment of the Clean Space Initiative, which has the objective of developing technologies to enable the capturing and de-orbiting or re-orbiting of space debris. She explained that ESA is looking to undertake a mission by 2022 to de-orbit one of their inactive satellites. Given the legal complexities associated with space debris remediation, ESA has decided to de-orbit one of its satellites rather than seek permission from another actor. Dr. Jaime Reed then introduced two methods of space debris remediation being developed and studied by Astrium; a net and a harpoon system designed to enable the de-orbiting or reorbiting of space objects. The net system was first developed as a concept in 2003, and demonstrations have indicated its potential as a space debris remediation technology. The harpoon system meanwhile is intended to be compatible with a multitude of targets with varying shapes and sizes and is designed to avoid the generation of debris during usage. Although both the net and harpoon systems are still in the relatively early stages of development, the underlying objective behind them is the introduction of low-cost re-useable space debris remediation technologies. With respect to drag-augmentation systems, Charlotte Bewick from OHB System AG presented research on the collision risks associated with deployment of such systems. She argued that whilst such methods have the capability to dramatically increase the speed with which small objects can be de-orbited, their use with regards to objects at altitudes of 800 km and above would introduce such significant risks of collision with other objects to negate the advantages of the accelerated de-orbiting. Turning to on-going research and development within the field of drag-augmentation systems, Vaios Lappas of the University of Surrey introduced a number of projects being developed for the purposes of debris remediation, including the CubeSail and DeorbitSail projects. These projects are designed demonstrate the capability of drag-augmentation systems to de-orbit space debris quickly and efficiently. The projects are undergoing testing on Earth at the moment, with a view to in-orbit testing commencing in the near future.
4. Space debris mitigation Space debris mitigation was discussed in a number of presentations though there were none dedicated specifically to it. Ms. Wheeler provided an overview a few of the existing national and international space debris mitigation guidelines, including the IADC Draft Space Debris Mitigation Guidelines, the Space Debris Mitigation Guidelines of the Scientific and Technical Subcommittee of UNCOPUOS, the European Code of Conduct for Space Debris Mitigation and the ESA Space Debris Mitigation Handbook. Although these guidelines are all non-binding recommendations, they are indicative of agreed-upon best practices for space debris mitigation. Nonetheless, Ms. Wheeler argued that international mitigation measures must be harmonised to avoid unfair competition. Luisa Innocenti of ESA also discussed the space debris mitigation measures associated with ESA’s Clean Space Initiative, which she described as a roadmap of technologies directed at environmental sustainability both on Earth and in orbit. These include technologies to ensure that ESA missions meet debris mitigation requirements, with an emphasis on post-operation passivation and disposal through de-orbiting and re-orbiting.
6. Space traffic control While the main conference title was Space Traffic Control, the event prioritised space debris over other possible associated themes. Professor Crowther contended during his presentation on best practice initiatives that space is becoming more ‘congested,
Please cite this article in press as: Slann PA, Space debris and the need for space traffic control, Space Policy (2013), http://dx.doi.org/10.1016/ j.spacepol.2013.10.007
P.A. Slann / Space Policy xxx (2013) 1e3
contested and competed’ and thus there needs to be an increased focus upon ‘safety, security and sustainability’. He outlined current and possible future forms of governance with regards to outer space affairs, including the International Telecommunications Union’s regulation of the radio-frequency spectrum and orbital resources, as well as the work of UNCOPUOS and, finally, Transparency and Confidence-Building Measures. Taking the UK as an example, Professor Crowther detailed the regulation process for space missions falling under the responsibility of the UK government, explaining that the Secretary of State requires licensees to operate in a manner that will prevent contamination of outer space, avoid adverse changes to the terrestrial environment and not interfere with the extra-terrestrial operations of other actors. Professor Crowther also discussed the need for governance of space debris remediation efforts, noting that although some systems show promise, their potential for misuse must be taken into account and mitigated. Concluding the conference, Dr. Stuart Eves of SSTL expanded on the other areas to which space traffic control may be applied, including improved space weather and solar monitoring, enhanced tracking of both debris and active satellites, notification of fragmentation events, prediction of re-entry events, conjunction predictions and warnings and notification of manoeuvres. Dr. Eves also commented on the need for improved frequency coordination, noting that this will be crucial given the expected future growth in the number of manned space missions, combined with the likelihood that some vehicles will be transitioning between air traffic and outer space traffic control standards.
3
7. Conclusions Four themes emerged during the conference; firstly that space debris is an urgent problem requiring both short-term and long-term solutions. Secondly, that space debris mitigation efforts can only go so far and thus the development and implementation of remediation technologies is necessary to prevent the onset of cascading debris generation. The third theme concerned the governance of space debris remediation efforts; there needs to be clearer legal guidance regarding liabilities and responsibilities, as well as transparency to ensure that remediation technologies are not misused or perceived as threats to other spacefaring actors. Finally, the fourth theme indicated that space traffic control extends beyond space debris to issues over frequency regulation, space weather and station-keeping manoeuvres. Whilst the conference was dedicated to space debris, a number of the presentations highlighted the need for further discussions of the wider applications of space traffic control. Regarding the sub-title of the conference, ‘is the space debris problem solvable?’, it would appear from the presentations that while there is the potential for future management of the issue through debris remediation and harmonised mitigation efforts, no comprehensive solutions exist at the time of writing. Reference [1] United Nations. United Nations Treaties and Principles on Outer Space Text of treaties and principles governing the activities of States in the exploration and use of outer space, adopted by the United Nations General Assembly, ST/SPACE/ 11, New York: United Nations, available from: http://www.unoosa.org/pdf/ publications/STSPACE11E.pdf. p. 6, [last accessed 03.09.13].
Please cite this article in press as: Slann PA, Space debris and the need for space traffic control, Space Policy (2013), http://dx.doi.org/10.1016/ j.spacepol.2013.10.007