Since the beginning of the space age, the outer space has been extensively used for communications, navigation, earth observation and climate monitoring. Communication satellites power telephony and the internet. Navigation satellites have provided us with the GPS, and other such systems, that make traversing the earth much easier. Reconnaissance or surveillance satellites observe the earth to detect changes alerting us about environmental deterioration, illegal activities or polluting emissions. Satellites, as evidenced by the war in Ukraine, can even warn us about the movements of enemy nations by detecting, for example, the accumulation of armies and weapons right on our borders ready for invasion. Satellites in the service of the World Meteorological Association have led to much more precise estimates about the anticipated magnitude of climate change. Satellites and the rockets that propel them to space have made possible the beginning of conquest of space, the much-touted final frontier of humanity.
Satellites can be placed on one of three orbital areas: low Earth orbit (LEO), medium Earth orbit (MEO), and geosynchronous orbit (GEO). In the beginning of the space age, it was only states that dominated space activities and missions. After 2015, a number of private actors have also been involved in space exploitation. This has led to the proliferation of space infrastructure as demonstrated by the development of mega-constellations of satellites, small satellites working together as a system that enable communications. Such satellite constellations, usually located at around 550 km above the earth’s surface at the LEO, are much more versatile than the big communication satellites set at 36 000 km at the GEO. Constellation satellites have been pioneered by commercial companies for the provision of internet in rural and less connected areas. Starlink, a private company, had launched 2 500 satellites by 2022 aiming to launch eventually 30 000 satellites in space. States are also becoming increasingly interested in mega-constellations of satellites. China is planning to place in orbit a constellation of 12 992 satellites.
In addition to functioning and operational satellites, all Earth’s orbits — the LEO, MEO and GEO—are populated by many non-operational satellites that have been abandoned at the end of their lives and used rocket bodies that have been used to launch satellites and other spacecraft. These abandoned space objects that linger on these orbits often collide, explode or break up due to natural decay generating dangerous space debris that have polluted the outer space environment.
There are two ways to get rid of non-functioning space objects: De-orbiting that involves the re-entry of a space object into the earth’s atmosphere; and re-orbiting — discarding a space object in an orbit above its current orbit. De-orbiting is made possible by the dynamics between earth and space, the so-called ‘atmospheric drag.’ The drag, that can be accelerated by the operator of a space object, pulls space objects from space into the earth’s atmosphere where they burn. What is not burnt reaches the earth’s surface, usually the ocean, as debris.
- Space Debris
Space debris or space junk consist of space objects that are no longer useful, such as decommissioned satellites or disused rockets. Most debris orbits the earth for many years until it decays, deorbits, explodes or collides with another object, generating more debris. As of 2023, the amount of space debris exceeded 8 000 metric tons— 8 000 000 kg. About 26 000 pieces of debris are the size of a softball. Such debris can destroy a satellite if they collide with it. Another 500 000 debris are the size of a marble. Upon impact with a satellite, they could cause significant damage. Approximately 100 million debris are as small as a grain of salt. Even these tiny debris, however, such as paint chips, can perforate a spacecraft because of their speed. Debris circles the earth at an average speed 10 km per second. This is 10 times faster than a bullet creating in effect thousands of missiles speeding randomly in space. At this speed, even millimeter-sized debris can cause damage. Given that most space objects are launched in LEO, most of debris— 71%— congregates there.
Most of the debris generated in GEO will remain in the GEO forever because they are located at a very high altitude and, therefore, cannot benefit from the self-cleaning effect performed by the atmospheric drug in LEO. At this point, disused space objects that operate in the GEO have to be removed from it by maneuvering them to a graveyard orbit. But this is not considered a permanent solution. Accumulating space objects in graveyard orbits is expected to eventually lead to accidental collisions among them and the resulting debris could potentially spill over to the GEO protected orbit.
Scientists are concerned that collisions among space debris can generate a collisional snowball cascading effect that could increase exponentially the quantity of debris in space. This effect, the so-called Kessler syndrome, has the capability of transforming the earth’s orbit into an unusable area filled with discarded material. It has been estimated that this can be mitigated, to some degree, if five large objects are removed from the earth’s orbit each year. But to actually reduce the quantity of debris in space, 10 large objects must be removed from the outer space every year. The space debris issue is compounded by the fact that the space agencies set up by governments do not have a complete picture of the whereabouts of debris populating the space environment.
Various debris mitigation methods and debris removal methods have been proposed to address space junk. The United States, the country that owns and operates most space infrastructure, has promulgated a number of guidelines geared to mitigate the creation of space debris. The US Orbital Debris Mitigation Standard Practices (ODMSP) were adopted in 2001. Their aim is to restrict the generation of new debris through collision avoidance, passive protection (shielding of spacecrafts) and end-of-mission disposal.
The pollution of the outer space by space debris has incentivized commercial operators to develop methods of active debris removal (ADR). The ADR requires three steps: a space rendezvous; the grappling of debris by various instruments; and the placing of debris on a lower altitude in order to reduce its remaining time in outer space. Various methods have been proposed to be used to grapple debris, including hooks, harpoons, nets, glue and tentacles. At this point, ADR is too expensive of a technology and has yet to be tested on a large scale. Furthermore, the firms that aspire to remove debris do not exactly know where the debris may be located. Information on debris, including its position, shape and mass, is not always accurate.
Furthermore, most states are ambivalent about the use of ADR because it is a dual use technology. A device equipped with hooks to remove space debris, for example, could also be used to remove or attack an operating satellite. Therefore, the international guidelines on space debris provide that space rendezvous, such as those involving the servicing of satellites or the removal of debris, must not happen without notification and consent. This is because a large percentage of space debris come from military spacecraft. It is very unlikely that launching states of military spacecraft will permit the ADR of a non-functioning such spacecraft. Furthermore, the information that must be provided to an ADR operator in order to perform a successful ADR mission could be protected by intellectual property rights owing to its economic or strategic value. Overall, given that the use of space is integral to the national security of states, states are reluctant to be transparent about their space activities and the objects they launch into space.
- International Treaties and Guidelines for Space Debris
The Inter-Agency Space Debris Coordination Committee (IADC) is an international governmental forum that provides coordination among national authorities with regard to the management of space debris. Members of the IADC include the CNSA (China National Space Administration), the ESA (European Space Agency), the ISRO (Indian Space Research Organization), the JAXA (Japan Aerospace Exploration Agency), the NASA (US National Aeronautics and Space Administration) and ROSCOSMOS (Russian State Space Corporation). The IADC has adopted space debris mitigation guidelines that have influenced the mitigation guidelines issued by the UN Committee on the Peaceful Use of Outer Space.
The UN Committee on the Peaceful Uses of Outer Space (COPUOS) is another international body that deals with space debris. The Debris Mitigation Guidelines adopted by COPUOS and endorsed by the UN General Assembly  define debris, as all human-made objects, including fragments and elements, found in earth’s orbit or re-entering the atmosphere, that are non-functional. According to the guidelines, the intentional destruction of any on-orbit spacecraft or rockets or other harmful activities that generate long-lived debris should be avoided. When intentional breakups are necessary, they should be conducted at sufficiently low altitudes to limit the orbital lifetime of resulting debris.  The guidelines further provide that space systems should be designed in ways that minimize the release of debris during normal operations. Both spacecraft and launch vehicles should be designed to avoid failure modes that lead to accidental breakups. In case a condition leading to such failure may be detected disposal and passivation measures must be planned to avoid breakups. Additionally, a regional instrument the draft Code of Conduct for Outer Space Activities proposed by the European Union, calls on states to undertake collision avoidance measures and to notify other states both before launching space objects and in the case of high-risk re-entries of such objects.
Guidance on space debris has been provided also by the UN General Assembly (GA). The GA adopted in 2021 a resolution on the establishment of an open-ended working group on reducing space threats through norms, rules and principles of responsible behavior.  The resolution stresses, inter alia, that the creation of long-lived orbital debris arising from the deliberate destruction of space systems increases the risk of in-orbit collisions and the potential for misunderstandings and miscalculations that could lead to conflict. In 2022, the GA approved a US-proposed resolution calling on states to commit to a moratorium on testing destructive anti-satellite weapons, with 155 countries voting yes, nine voting no including Russia, China and Iran, and nine nations abstaining including India. The UN resolution is not binding. It signals, however, that there is widespread support for such a moratorium. Canada, New Zealand, Germany, Japan, the United Kingdom, South Korea, Switzerland, Australia and France have pledged to abstain from Anti-Satellite (ASAT) testing.
The plethora of guidelines with regard to space debris has to do with the fact that none of the international treaties that define the regime that governs the outer space explicitly addresses such debris.
Article VII of the Outer Space Treaty (OST) provides that each state that launches or procures the launching of an object into outer space and each state from whose territory or facility an object is launched is internationally liable for the damage to another state and to the persons of another state by such object or its components. The question that emerges, thus, is: Could debris be characterized as components of a space object? Logically they should; but many of the dangerous debris are tiny and it is unclear whether such debris could still be called ‘components’ of a space object. And even if they could, it would be hard, in many cases, to identify the space object from which they originated and, thus, the launching state of that object.
Article VIII of the OST builds upon the percept of holding launching states accountable. The article provides that the state of registry of an object launched into outer space must retain jurisdiction and control over such object. Ownership of objects launched into outer space and of their component parts is not affected by their presence in outer space. This means that states cannot disclaim ownership with regard to the debris generated by their space objects. If a state loses control over a space object because it has ceased to function, it still retains legal jurisdiction and control over that object based on the OST. As a result, space objects and their components or debris cannot be legally abandoned and remain under the ownership and responsibility of the launching state.
In fact, states have shown no interest in abandoning their space debris, often for national security reasons. As a result, the unauthorized targeting or removal of a non-functioning space object, meaning their removal without the launching state’s consent, could be interpreted as a hostile act that might generate conflict among states. An issue that must be addressed, at one point, is whether it is possible to introduce a workable legal presumption that certain debris, based on their size (e.g., debris less 1cm) or mass can be actively removed from space without the authorization of launching states. If such presumption is introduced a subsequent matter that must be addressed is which organization could be possibly trusted with the safe removal of such debris.
Based on the OST, states bear international responsibility for national activities in outer space whether such as activities are carried on by government agencies or by non-governmental entities. It makes sense to conclude from this provision that since states are internationally responsible for their activities in outer space, they should also be responsible for the debris generated from such activities no matter whether the debris was generated by state or non-state actors.
It is unclear whether the creation of space debris constitutes harmful contamination of outer space. With regard to this matter, article IX of the OST provides that states shall conduct exploration of outer space, including the moon and other celestial bodies, in a way that avoids their harmful contamination. One could potentially argue that the creation of hazardous, toxic or radioactive debris that have been abandoned in outer space, without contemplating measures for their proper disposal, does constitute harmful contamination of the outer space.
The Space Liability Convention could be used to seek compensation in case space debris causes damage to another state or its nationals. However, the liability convention does not include in any of its articles the term ‘space debris.’ It provides that the launching state is absolutely liable for damage caused by its space object and that object’s components on the surface of the earth or to an aircraft in flight. This strict liability rule does not require the state that has suffered damage to prove the fault of the launching state. The launching state is liable simply because it caused damage to another state by sending an object to space.
However, if damage is caused elsewhere than on the surface of the earth, the launching state will be only liable if the damage is due to its fault or the fault of persons for whom it is responsible. In the case of fault liability, it is the state that has suffered damage that must prove that the launching state acted with negligence in a way that violates the law or common safety practices governing behavior in space. While such safety practices are being currently established in the form guidelines, they hardly existed in the past. For example, with regard to the 2009 collision between the Kosmos 2251 and the Iridium 33 satellites one could have claimed that Russia was negligent because it should have de-orbited its Kosmos satellite when it became defunct in 1995. But while according to today’s standards it is considered good practice to de-orbit non-operational satellites, this was not the standard practice in 1995. In fact, at that time, states just abandoned their satellites when they were no longer operational.
The Space Liability Convention defines damage as loss of life, personal injury or loss or damage to property of states and persons. Damage to the environment is not covered, unless such damage has caused damage to property. Article XII provides that the compensation which the launching state has to pay must be determined in accordance with international law and the principles of justice and equity, the goal being to restore the person who suffered from damage ‘to the condition which would have existed if the damage had not occurred.’
The COPUOS adopted in 2018 by consensus Guidelines for the Long-Term Sustainability of Outer Space Activities. The purpose of the guidelines is to ensure that space remains an operational, stable and safe environment maintained for peaceful purposes and open for exploration, use and international cooperation by current and future generations in the interest of all, irrespective of their degree of economic or scientific development and with due regard to the principle of equity. The guidelines constitute a compendium of internationally recognized practices and measures geared to ensure the long-term sustainability of outer space activities with special emphasis on enhancing the safety of space operations.
The guidelines declare that the earth’s orbital space constitutes a finite source that is increasingly used by a number of states, INGOs and NGOs. They address additional matters, such as national regulation and supervision of space operations of non-governmental entities by states; improving the timely practice of registration of space objects; establishing a harmonized system for exchange of information on space objects and events, such as uncontrolled re-entries, based on common internationally recognized standards; and sharing space debris monitoring information. Other matters addressed in the guidelines include methodologies and consultative processes for assessing the probability of collisions and making avoidance-maneuver decisions, sharing space weather data in a free and unrestricted manner for mutual benefit, investigating the adoption of new measures for the long-term management of space debris and ensuring that such measures ‘do not pose an undue risk to people or property, including through environmental pollution caused by hazardous substances.’
The guidelines provide that spacecraft and launching vehicles that have terminated their operational phases in orbits that pass through the LEO region should be removed from orbit in a controlled fashion. If this is not possible, they should be placed in orbits that avoid their long-term presence in the LEO region. Spacecraft and rockets that have terminated their operational phases in orbits that pass through the GEO region should be moved into orbits that avoid their long-term interference with the GEO region. For space objects in or near the GEO region, the potential for future collisions can be reduced by leaving objects at the end of their mission in an orbit above the GEO region such that they will not interfere with, or return to, the GEO region. The guidelines further call for the development of spacecraft design that will increase the trackability of space objects.
The pollution of space by debris needs to be addressed urgently by states by establishing compulsory norms with regard to the management, minimization and disposal of space waste. Unfortunately, this is not likely to happen in the near future as states continue to behave opportunistically with regard to the governance of space. Large spacefaring nations are continuing to treat the outer space as ‘another high seas’ promoting the freedom of navigation and adoption of non-binding rules that are unlikely to curb the unfettered exploitation of space. Developing states seem also to disfavor binding rules since they view that have yet to exploit the outer space and they have not, thus, contributed to generation of space junk, such junk being the responsibility of developed states.
This opportunistic attitude towards the governance of outer space is likely to produce a tragedy of commons, like the tragedy that has afflicted the high seas, the air and other elements of the earth’s environment.
 The Satellites that Saved Ukraine, Economist, Jan. 7, 2023.
 NASA Office of Inspector General, NASA’s Efforts to Mitigate the Risks Posed by Orbital Debris, at 1, Jan. 27, 2021.
 Id. at 2.
 Id. at 3.
 International Academy of Astronautics, IAA Situation Report on Space Debris, at 15 (2016).
 Id. at 118.
 Id. at 119.
 Id. at 120.
 Id. at 144.
 NASA Office of Inspector General, supra note 2, at 22.
 A space rendezvous involves orbital maneuvers so that two spacecraft can meet at the same orbit and can approach each other very closely.
 International Academy of Astronautics, supra note 5, at 128.
 Jon Sindreu, The Difficult Search for Dangerous Space Junk, WSJ, Nov. 14, 2022.
 Open-Ended Working Group on Reducing Space Threats through Norms, Rules and Principles of Responsible Behaviors, Chair’s Summary of Discussions under Agenda Item 6(b), UN Doc. A/AC.294/2002/4, Oct. 5, 2022, para. 7.
 International Academy of Astronautics, supra note 5, at 153.
 Id. at 16.
 The IADC Space Debris Mitigation Guidelines were adopted in 2002 and are being revised periodically. The latest revision was adopted in 2021.
 UN Office for Outer Space Affairs, Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space (2010) [Guidelines], https://www.unoosa.org/pdf/publications/st_space_49E.pdf.
 International cooperation in the peaceful uses of outer space, UN Doc. GA/RES/62/217, Feb. 1, 2008.
 Guideline 4, supra note 18.
 Guideline 1, id.
 Passivation means the elimination of all stored energy on a spacecraft, such as batteries and fuel.
 Guideline 2, supra not3 18.
 International Code of Conduct for Outer Space Activities, Mar. 31, 2014, https://www.eeas.europa.eu/sites/default/files/space_code_conduct_draft_vers_31-march-2014_en.pdf.
 Other standards adopted with regard to space debris include the ISO Standard 24113.
 Reducing space threats through norms, rules and principles of responsible behaviors, UN Doc. A/RES/76/231, Dec. 30, 2021.
 Destructive direct-ascent anti-satellite missile testing, UN Doc. A/C.1/77/L.62, Oct. 13, 2022.
 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, Jan. 27, 1967, 18 U.S.T. 2410, 610 U.N.T.S. 205.
 Art. VI, supra note ___.
 Convention on International Liability for Damage Caused by Space Objects, Mar. 29, 1972, 24 U.S.T. 2389, 961 U.N.T.S. 187.
 ‘Space object includes component parts of a space object as well as its launch vehicle and parts thereof. See art. I, id.
 Art. II.
 Art. III.
 Art. I(a).
 Committee on the Peaceful Uses of Outer Space, Guidelines for the Long-Term Sustainability of Outer Space Activities, UN Doc. A/AC.105/2018/CRP.20, June 27, 2018.
 Para. 4, id.
 Para. 3, id.
 Guidelines A. 2-A3, id
 Guideline A. 5, id.
 Guidelines B.1-B.2, id.
 Guideline B.3, id.
 Guidelines B.4-B.5, id.
 Guidelines B.6-B.7, id.
 Guideline D.2(4), id.
 Guideline A.4, id.
 Guideline B.8(1), id.
About the author
President, Law-in-Action, Princeton, New Jersey, USA