<div><div>Anti-satellite is often used as a synonym of <a href="https://spacesecuritylexicon.org/terminology/counterspace-capabilities">counterspace capabilities</a>, but it is more commonly understood to refer to a subset of counterspace technology, as it focuses on targeting one component of <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a> (the <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellite</a>). While most consider ASATs to refer to any form of counterspace capability that targets the <a href="https://spacesecuritylexicon.org/common-definition/space-segment">space segment</a> of a system, there are some that use this term to refer only to kinetic or destructive (hardkill) counterspace capabilities.</div></div>

Anti-Satellite (ASAT) 

<div><div>Counterspace capabilities refers to capabilities, techniques, or assets that can be used against another <a href="https://spacesecuritylexicon.org/common-definition/space-object">space object</a> or a component of a <a href="https://spacesecuritylexicon.org/common-definition/space-system">space system</a> in order to deliberately deny, disrupt, degrade, damage or destroy it reversibly or irreversibly, so as to gain advantage over an adversary. Counterspace technologies or capabilities can be offensive and defensive, and can be further classified into different groups including <a href="https://spacesecuritylexicon.org/terminology/kinetic-physical-hard-kill">kinetic physical</a>, <a href="https://spacesecuritylexicon.org/terminology/non-kinetic-physical">non-kinetic physical</a>, <a href="https://spacesecuritylexicon.org/terminology/electronic-electromagnetic-counterspace-capabilities">electronic</a>, and <a href="https://spacesecuritylexicon.org/terminology/cyber-counterspace-capabilities">cyber</a>. This is not a closed list, nor are these terms universally used by all States, and there are some lists that include other categories.* Another common classification is the division into <a href="https://spacesecuritylexicon.org/terminology/kinetic-physical-hard-kill">hard-kill</a> (which generally refers to physical hostile operations —especially those that use kinetic force— that result in the destruction of space objects), and <a href="https://spacesecuritylexicon.org/terminology/non-kinetic-soft-kill">soft-kill</a> counterspace technologies (which refers to non-physical interference that renders space assets impaired, ineffective, or inactive). Neither of these terms, nor their definitions, are universally accepted or used. </div></div>

Counterspace Capabilities

<div><div>These technologies can target data and the systems that use, transmit, and control the flow of data. Information and communication technologies can be used to target <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellites</a> as well as ground stations or even end-user components, such as modems, with the objective of interfering with services (such as Internet coverage), intercepting information, or inserting false or corrupt data into a system. Hostile operations that use cyber means or methods are generally reversible; however, a malicious or hostile operation that targets the command and control system of a satellite could render it inoperable in an irreversible way, as the hostile party could cause a stoppage of the satellite’s functions permanently, and cause it to waste its fuel or damage its sensors. Such a step could have a large impact radius and potentially affect <a href="https://spacesecuritylexicon.org/terminology/critical-infrastructure">critical infrastructure</a>. The use of information and communication technologies against <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a> can be conducted in a relatively cheap manner, compared to other counterspace capabilities. Cyber <a href="https://spacesecuritylexicon.org/terminology/counterspace-capabilities">counterspace capabilities</a> can be difficult to predict, detect, and attribute.</div></div>

Cyber Counterspace Capabilities

<div><div>Electronic counterspace technologies, sometimes also known as electromagnetic technologies, can target the electromagnetic spectrum used by <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a> to transmit and receive data, causing <a href="https://spacesecuritylexicon.org/terminology/harmful-interference">harmful interference</a>. </div><div><li><b>Jammers</b> generate noise on the same radio frequency band as a space system in order to block or interfere with the signal travelling from Earth to a <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellite</a> (uplink) or from a satellite to Earth (downlink). </li><li><b>Spoofing </b>is used to trick the system into believing a fake signal produced by a hostile party, thus enabling the hostile party to insert false information into the system including, but not limited to, false data or false commands which can disrupt operations or cause any of the components of a space system to act in a way other than how it was intended. </li></div><div>Hostile operations using these technologies are generally reversible, and are difficult to attribute to a perpetrator.</div></div>

Electronic / Electromagnetic Counterspace Capabilities

<div><div>Also known as simply ‘kinetic’, or ‘kinetic impactors’, these technologies can be used to strike a <a href="https://spacesecuritylexicon.org/common-definition/space-system">space system</a> component directly or to detonate a warhead near it. Although most deem kinetic and hard-kill to be synonyms, there are some that consider the former to refer solely to those capabilities dependent on the destructive power generated by their motion and interception trajectory, instead of an explosive. Hardkill, on the other hand, is a broader term that comprises kinetic physical capabilities, but also includes the aforementioned explosive <a href="https://spacesecuritylexicon.org/common-definition/payload-2">payloads</a>. Kinetic physical capabilities are sometimes referred to as hit-to-kill. It should be noted that official United Nations nomenclature does not use the terms ‘kinetic physical’ or ‘hardkill’.*</div><div>A kinetic physical or hard-kill hostile act can be carried out in different manners:</div><div><li><b>Direct-ascent ASATs</b> are launched from the Earth (ground, sea, or air) to place a kinetic kill vehicle on a ballistic trajectory through space. Once the kinetic kill vehicle has separated from the launch vehicle, it tracks the targeted <a href="https://spacesecuritylexicon.org/common-definition/space-object">space object</a> to strike it in a hypervelocity collision.</li><li><b>Co-orbital ASATs</b> place an interceptor into orbit, which is then manoeuvred using a <a href="https://spacesecuritylexicon.org/common-definition/rendezvous-and-proximity-operations-rpo">rendezvous and proximity operation</a> (RPO) to situate it close to its target. This manoeuvre does not necessarily take place immediately after the object is put in orbit and the co-orbital ASAT can remain dormant for some time. Satellites used as weapons by causing them to collide with another satellite, or the employment of projectiles by satellites, are also considered co-orbital ASATs, even if they are repurposed for this function despite having been designed for a benign and non-weapons-related application that is in line with the peaceful purposes principle. A kinetic co-orbital ASAT can damage or destroy its target through a direct collision, detonation in close proximity to the target to create shrapnel, the release of fragments that would collide with the target, or the use of a robotic arm to damage or disable the target. Certain concepts for co-orbital ASATs may employ various means or methods including, but not limited to, explosive fragmentation, harpoons, nets, chemical sprayers or adhesives.</li><li><b>Ground station</b> hostile actions consist of the targeting of sites located on Earth which are responsible for the command and control of a <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellite</a>, or the relay of satellite data.</li></div><div>The use of kinetic counterspace technologies is likely to cause irreversible damage to the target in a manner that is relatively easy to attribute. If the target is located in orbit, the use of these technologies produces <a href="https://spacesecuritylexicon.org/common-definition/space-debris">space debris</a>, which can be dangerous to other space objects as well, and can remain in orbit for weeks, months, or even years, depending on the altitude of the strike and the mass of the target.</div></div>

Kinetic Physical/Hard-Kill

<div><div>These technologies can be used to disable or destroy a <a href="https://spacesecuritylexicon.org/common-definition/space-system">space system</a> or one of its components without necessitating a direct strike. They can be further classified into <a href="https://spacesecuritylexicon.org/terminology/non-kinetic-physical">non-kinetic physical</a>, <a href="https://spacesecuritylexicon.org/terminology/electronic-electromagnetic-counterspace-capabilities">electronic</a>, and <a href="https://spacesecuritylexicon.org/terminology/cyber-counterspace-capabilities">cyber</a>. Soft-kill capabilities are usually hard to detect and attribute, and can be both reversible and irreversible.</div></div>

Non-Kinetic / Soft-Kill

<div><div>These technologies have physical effects on <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellites</a> or <a href="https://spacesecuritylexicon.org/common-definition/ground-segment">ground segments</a> without making physical contact. They include lasers, high-powered microwaves (HPM), and electromagnetic pulses (EMP). These technologies can blind or dazzle sensors or cause damage to electrical circuits and processors in a satellite. Non-kinetic physical hostile acts operate at the speed of light and, in some cases, can be less visible to third-party observers and more difficult to attribute. These acts can be reversible or irreversible.</div></div>

Non-Kinetic Physical

<div><div>Due diligence is generally understood as a duty of States to not “allow knowingly their territory to be used for acts contrary to the rights of other States”. This principle was articulated in the International Court of Justice’s Corfu Channel decision, and was a predecessor to the more general and all-encompassing idea of ‘<a href="https://spacesecuritylexicon.org/terminology/due-regard">due regard</a>’. In the context of <a href="https://spacesecuritylexicon.org/common-definition/space-activities">space activities</a>, the principle of due diligence obliges States to observe certain conduct with respect to a particular activity, in line with the obligation enshrined in article VI of the Outer Space Treaty (OST) which mandates States to carry out “continuing supervision” of the space activities of their nationals. The concept of due diligence is used in conjunction with fault standards applicable to space activities when analysing <a href="https://spacesecuritylexicon.org/terminology/liability">fault-based liability</a> for damages being caused elsewhere than on the surface of the Earth under article III of the Liability Convention. </div></div>

Due Diligence

<div><div>Article IX of the OST establishes the obligation for States to conduct space operations with “due regard to the corresponding interests of all other States Parties”. This due regard obligation is an explicit limitation on the freedom to use and explore outer space guaranteed by article I of the OST. The concept of ‘due regard’ is not defined in the OST, and as such there is no uniform consensus regarding its meaning. However, under other sources of international law, such as the law of the sea —which States have expressed can be adapted and applied to outer space* — ‘due regard‘ means that States are bound to refrain from any acts that might adversely affect the use of a domain by other stakeholders prior to and while conducting activities in that domain. Under the due regard principle, States are obligated to take the rights of other States into account when exercising their own rights. Related to the concept of ‘due regard’ is the duty of States to undertake international consultations before proceeding with any activity that might cause <a href="https://spacesecuritylexicon.org/terminology/harmful-interference">harmful interference</a> with activities of other State parties. Under article IX of the OST, other States may also request consultations if they have reason “to believe that an activity or experiment planned by another State Party in outer space [...] would cause potentially harmful interference with activities in the peaceful exploration and use of outer space” either prior to or during the performance of the space activity.</div></div>

Due Regard

<div><div>Article I of the Outer Space Treaty states that </div><div>“The exploration and use of outer space, including the Moon and other celestial bodies, shall be carried out for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development, and shall be the province of all mankind.<br /><br />Outer space, including the Moon and other celestial bodies, shall be free for exploration and use by all States without discrimination of any kind, on a basis of equality and in accordance with international law, and there shall be free access to all areas of celestial bodies.”</div><div>At the time of the drafting of the OST in 1967, there were very few spacefaring States, and thus the intention of this article was to ensure that non-spacefaring States would also be able to benefit from the discoveries and use of outer space.</div><div>The OST establishes outer space as a domain that is free for exploration and use by all States, but those freedoms are not unbridled. The benefits of space exploration are to be shared on the basis of equality and non-discrimination, irrespective of whether a State is spacefaring or not. Article I of the OST should be read in conjunction with article IX, which establishes the duty of <a href="https://spacesecuritylexicon.org/terminology/due-regard">due regard</a>, by which States are obligated to refrain from any acts that might adversely affect the use of outer space by other stakeholders in space prior to and while conducting <a href="https://spacesecuritylexicon.org/common-definition/space-activities">space activities</a> and take the rights of other States into account when exercising their own rights. </div><div>Due to this article, outer space is often referred to as “the province of all [hu]mankind”, particularly in policy circles; however, legal experts often note that what the OST establishes as “the province of all [hu]mankind” is not outer space itself, but rather its use and exploration. This distinction has gained particular relevance in the context of determining the legal status of resource extraction.</div><div></div></div>

Exploration and Use of Space as the Province of All [Hu]Mankind 

<div><div>Under article IX of the OST, States are obligated to avoid the harmful contamination of space. This concept is generally understood in a broad sense, covering all possible changes of the outer space environment —unintentional or deliberate— that would result in harm to the activities of other actors. In this sense, the creation of <a href="https://spacesecuritylexicon.org/common-definition/space-debris">space debris</a> would be an example of a form of harmful contamination. It should be noted, however, that article IX does not specify what measures would be appropriate to avoid harmful contamination and when such measures should be adopted, that is to say, what degree or level of care is required of States to avoid harmful contamination.</div><div>Harmful contamination can also refer more specifically to adversely changing outer space and celestial bodies with contaminants from Earth. Similarly, article IX of the OST establishes the obligation of avoiding “adverse changes” to Earth’s environment through the introduction of extraterrestrial matter. Some consider harmful contamination and adverse changes to be separate legal concepts —the former referring exclusively to space and celestial bodies, and the latter referring only to Earth— however there are others that consider both of these concepts to be contained under the umbrella of harmful contamination; having distinguished between two types of contamination stakeholders should be aware of and seek to avoid: </div><div><li><b>Forward contamination</b> refers to the introduction of Earth microbes to other planets.</li><li><b>Backward contamination</b> refers to bringing extraterrestrial matter back to planet Earth in manner that would create “adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter”. </li></div></div>

Harmful Contamination

<div><div>Harmful interference is generally understood to mean the external blocking or lessening of services provided by <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a>, which can be accidental or intentional, and includes interference with any space services ranging from commercial services to critical safety-of-life applications. Article IX of the OST establishes that if a State believes that its activity or an activity of its nationals would cause “potentially harmful interference” with the activities of other States Parties, then it shall undertake “appropriate international consultations” before proceeding with the activity. Moreover, the OST gives a potentially affected State the opportunity to request consultations if it has reason to believe that another State’s activity could cause potentially harmful interference with its peaceful exploration and use of outer space. This consultations process is recognized as a prerequisite for the effective environmental protection of outer space. However, it has never been used and there is no guidance on what constitutes a consultation.</div><div>While the OST does not define the concept of harmful interference, the concept is defined in both No. 1.169 of the Radio Regulations and in No. 1003 of the ITU Constitution, as “interference which endangers the functioning of a radionavigation service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance with Radio Regulations”.</div></div>

Harmful Interference

<div><div>Liability generally refers to the legal obligation to compensate another for injury following an event that causes damage. The Outer Space Treaty establishes a liability obligation in article VII, by which “Each State Party to the Treaty that launches or procures the launching of an object into outer space, including the Moon and other celestial bodies, and each State Party from whose territory or facility an object is launched, is internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by such object or its component parts on the Earth, in air space or in outer space, including the Moon and other celestial bodies”. </div><div>There is a fundamental, substantive difference between the concept of article VI (international responsibility) and article VII (international liability). This difference can create interpretative difficulties as some languages use the same word to refer to both concepts —for example Spanish (<i>responsabilidad</i>) and French (<i>responsabilité</i>).</div><div>The liability obligation is financial or pecuniary in nature, thus entailing a duty to compensate (pay money to) another State for damages caused by its <a href="https://spacesecuritylexicon.org/common-definition/space-object">space objects</a>. <a href="https://spacesecuritylexicon.org/terminology/responsibility">Responsibility</a> involves a State’s duty to authorize and continually supervise the activities of its nationals, and to ensure that the “national activities are carried out in conformity” with the provisions of the OST. </div><div>The Convention on International Liability for Damage Caused by Space Objects expands further on this obligation, distinguishing between two distinct types of liability:</div><div><li><b>Absolute liability</b> (article II): if a space object causes damage to an object “on the surface of the Earth or to aircraft in flight”, the launching State of that space object shall be absolutely liable. Under this absolute standard, a State must compensate a victim State for damages, whether or not the launching State was at fault.</li><li><b>Fault-based liability</b> (article III): when there is a “damage being caused elsewhere than on the surface of the Earth to a space object of one launching State or to persons or property on board such a space object by a space object of another launching State”, the standard is fault-based liability. To determine the existence of fault, a tribunal (or commission) applying the Convention would assess the specific facts of the case, as well as the conduct of the launching State.</li></div><div>A launch may involve multiple launching States and, according to the Liability Convention, each may be held jointly and severally liable for damage. Specifically, a claimant may pursue its claim against any of the launching States, each of which could be 100 per cent responsible for paying the claim. After the claimant is compensated, any division or proportion of liability among the defendant launching States could be addressed subsequently.</div><div></div></div>

Liability 

<div><div>Outer space refers to the region or expanse that exists beyond the Earth and between celestial bodies. There is no international consensus as to where airspace ends and outer space begins, particularly since these terms have not been properly defined in international law. Some experts have argued that space extends down to 100 km above sea level. This is so because at their lowest orbital point, or perigee, some <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellites</a> have operated at around 100 km (328,000 feet or 62 miles). This approximate altitude is known as the von Kármán line, commonly referenced as the point for air versus space demarcation and the point at which it is believed an aircraft would have to reach orbital velocity to produce enough lift to remain aloft. There are others, however, who argue that the delimitation should be lower, establishing the delimitation altitude at 80 km above sea level in order to account for suborbital <a href="https://spacesecuritylexicon.org/common-definition/spacecraft">spacecraft</a> as well as hybrid aerospace vehicles capable of operation both in airspace and outer space. </div><div>There are currently two main schools of thought that have emerged with the objective of answering the delimitation question. On the one hand, ‘spatialism’ essentially argues for a fixed line, at a set altitude, for the division of airspace and outer space. On the other hand, ‘functionalism’ focuses on the nature of the craft in question: the applicable law will depend on the functions it serves.</div><div>It should be noted that some domestic space law definitions establish a specific delimitation for the purposes of licensing. </div></div>

Outer Space (Delimitation)

<div><div>Under the OST, outer space shall be used for “peaceful purposes”. This is stated in the non-binding preambulatory text, which states that there is a “common interest of all [hu]mankind in the progress of the exploration and use of outer space for peaceful purposes”, and also in article IV, which establishes that “[t]he Moon and other celestial bodies shall be used by all State Parties to the Treaty exclusively for peaceful purposes”. Although the drafters of the OST chose not to establish the use of space for peaceful purposes as a more general obligation in the text of the Treaty, it has nevertheless been posited that such concept has now achieved the status of customary international law, due to the fact that it consistently appears in General Assembly resolutions that have garnered unanimous or near unanimous support from the international community. Moreover, the term’s consistent appearance in domestic laws and policies relating to outer space is indicative of its prevalent recognition as a legal obligation.</div><div>While this is a generally accepted obligation, the meaning of “peaceful purposes” is not understood by all in the same manner. Many States understand “peaceful purposes” to mean non-aggressive or non-hostile uses or activities, rather than non-military. However, there are some that have argued this concept should be understood to mean ‘non-military’, in line with the understanding in other arms control domains, where the concept of ‘military purposes’ is always considered non-peaceful. Widespread State practice with regard to the use and exploration of space supports the former interpretation (that military space activities can be peaceful) and, as such, outer space is now filled with satellites used for military purposes such as intelligence gathering, reconnaissance, navigation, targeting over battlefields, early warning of missile and air hostile operations, or military communications, usually without protest from the international community. This interpretation has also allowed for the development and even testing of counterspace technologies, and several stakeholders have warned that this hints at a <a href="https://spacesecuritylexicon.org/terminology/weaponization-of-outer-space">weaponization of outer space</a> that could eventually lead to conflict.</div></div>

Peaceful Use And Exploration Of Outer Space / Peaceful Purposes

<div><div>States are obliged by the OST and the Registration Convention to provide certain information about their own <a href="https://spacesecuritylexicon.org/common-definition/space-object">space objects</a> to (i) a domestic registry maintained by the State, and (ii) an international Register maintained by the Secretary-General of the United Nations. </div><div>The duty to establish a national registry is mentioned for the first time in article VIII of the OST which establishes that “A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body”. Space objects or their component parts “found beyond the limits of the State Party to the Treaty on whose registry they are carried shall be returned to that State Party”.</div><div>Moreover, the Registration Convention establishes in its articles II–IV, (i) the duty of a State to “register the space object by means of an entry in an appropriate registry which it shall maintain. Each launching State shall inform the Secretary-General of the United Nations of the establishment of such a registry” (article II), and (ii) the duty of the international community to establish an international Register which shall be maintained by the Secretary-General (article III), in which certain information pertaining to the object shall be included. In particular (article IV):</div><div>a) Name of the launching State or States;<br />b) An appropriate designator of the space object or its registration number;<br />c) Date and territory or location of launch;<br />d) Basic orbital parameters, including:<br />     (i) Nodal period;<br />     (ii) Inclination;<br />     (iii) Apogee;<br />     (iv) Perigee;<br />e) General function of the space object.</div><div>To date, over 85 per cent of all <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellites</a>, probes, landers, crewed <a href="https://spacesecuritylexicon.org/common-definition/spacecraft">spacecraft</a> and space station flight elements launched into Earth orbit or beyond have been registered with the Secretary-General. States commonly call for better compliance with the international obligation to register objects, particularly at the international level, with some States even calling for the enhancement of the practice of States and international intergovernmental organizations in registering space objects. Registration is widely seen as a measure that could foster trust and confidence among States and which would facilitate the <a href="https://spacesecuritylexicon.org/terminology/verification">verification</a> and <a href="https://spacesecuritylexicon.org/terminology/monitoring">monitoring</a> of States’ compliance with legal and normative frameworks.</div><div>In the context of the ITU, the Master International Frequency Register (the Master Register) contains frequency assignments together with their particulars as notified in accordance with the Radio Regulations. The international rights and obligations of national administrations in respect to frequency assignments shall be derived from the recording of those assignments in the Master Register or from their conformity, where appropriate, with a Space Plan. The term ‘frequency assignment’ refers either to a new frequency assignment or to a change in an assignment already recorded in the Master Register. For such an assignment, the right to international recognition means that other national administrations shall take it into account when making their own assignments, in order to avoid <a href="https://spacesecuritylexicon.org/terminology/harmful-interference">harmful interference</a>.</div></div>

Registration

<div><div>The duty of responsibility with regard to activities in space is enshrined in article VI of the OST, which determines that States “bear international responsibility for national activities in outer space”, whether they are carried out by governmental agencies or non-governmental entities. Furthermore, States are responsible for assuring that the activities of their nationals “are carried out in conformity with the provisions” of the OST. Article VI also obliges States to authorize and continually supervise the activities of its nationals (including non-governmental entities) and to ensure that the “national activities are carried out in conformity” with the provisions of the OST. It is distinct from the concept of <a href="https://spacesecuritylexicon.org/terminology/liability">liability</a>, which imposes a financial (or pecuniary) obligation to compensate (pay money to) another State for damages caused by its <a href="https://spacesecuritylexicon.org/common-definition/space-object">space objects</a>.</div><div>Article VI of the OST expressly stipulates that anything done by a non-governmental entity in outer space is considered to be an act that is imputable to the State as if it were its own, and thus the State bears direct responsibility for such act. Article VI’s stipulation that a State is responsible for its national activities in outer space was a significant development in public international law, as it is a marked difference from the regime of State responsibility applicable to activities on Earth. In the context of space law, a State cannot avoid responsibility by disclaiming responsibility for the acts of its private persons. The way many States implement their article VI responsibilities is through the enactment of national laws and regulations.</div><div>The legal concept of responsibility should not be confused with the policy concept of ‘responsible behaviour’ which has been used by several States to encourage members of the international community to carry out space activities in a manner that seeks to preserve <a href="https://spacesecuritylexicon.org/terminology/space-sustainability">space sustainability</a> and avoid the increase of tensions by negatively impacting other States and their <a href="https://spacesecuritylexicon.org/common-definition/space-activities">space activities</a>. The use of the term ‘responsible behaviour’ in the context of <a href="https://spacesecuritylexicon.org/terminology/space-security">space security</a> regulations has been criticized by some States as vague and difficult to assess or verify. There is no universally accepted definition of the term ‘responsible behaviour’.</div></div>

Responsibility

<div><div>There is no universally accepted definition of critical infrastructure in the context of <a href="https://spacesecuritylexicon.org/terminology/space-security">space security</a>. In the context of cybersecurity, the UN General Assembly has highlighted that critical infrastructures include “those used for, inter alia, the generation, transmission and distribution of energy, air and maritime transport, banking and financial services, e-commerce, water supply, food distribution and public health—and the critical information infrastructures that increasingly interconnect and affect their operations”.* Critical infrastructure is considered of fundamental importance and “the backbone of a society’s vital functions, services and activities. If these were to be significantly impaired or damaged, the human costs as well as the impact on a State’s economy, development, political and social functioning and national security could be substantial”.**</div><div>As space technology is now integrated into almost all essential sectors and functions (including defence, agriculture, transportation, energy, and telecommunications), several stakeholders have called for its designation as a critical infrastructure sector, both at the domestic and international levels. Some States include <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a> as critical infrastructure in their domestic legislation and policies.</div></div>

Critical Infrastructure

<div><div>The term ‘dual-use’ is often used to refer to <a href="https://spacesecuritylexicon.org/common-definition/space-object">space objects</a> that (i) have both military and civilian functions, on the one hand, or that (ii) can be repurposed to be used for aggressive objectives. Some have suggested distinguishing between utilizing the term ‘dual-use’ for the former and ‘dual-purpose’ for the latter. Under such distinction:</div><div><li><b>Dual-use</b> refers to those space objects that can have (i) military and security, as well as (ii) civilian and commercial functions (such as, for example, <a href="https://spacesecuritylexicon.org/common-definition/global-navigation-satellite-system-gnss">GNSS</a>). These uses can be carried out either simultaneously or alternately (the latter is sometimes known as ‘dual-capable’). Dual-use objects see the integration of military and civilian functions in one single object. </li><li><b>Dual-purpose</b> refers to those space objects that are designed to fulfil a benign objective (such as debris removal or on-orbit servicing), but they could potentially be repurposed to harm other space objects. Dual-purpose objects are in principle not designed or expected to perform military functions directly —although they may provide some form of support to military satellites through <a href="https://spacesecuritylexicon.org/common-definition/satellite-servicing">on-orbit servicing</a>, for example— and they are also not intended to perform aggressive or hostile actions against other satellites. </li></div><div>Although dual-use and dual-purpose are different categories of objects, some overlap between the two is possible. In this sense, a dual-use object could also be a dual-purpose object if it possesses certain capabilities which could potentially be repurposed to harm another satellite (such as manoeuvrability, a capability that could be utilized to cause a satellite to collide with another). </div><div>The distinction between dual-use and dual-purpose is not universally accepted. Neither ‘dual-use’ nor ‘dual-purpose’ are terms of art in international law.</div></div>

Dual-Use

<div><div>Militarization of outer space refers to any military activity in outer space (whether hostile or not, or whether weapons-related or not) or any activity that supports military operations. Many argue that outer space has been militarized since the early days of space exploration, thus highlighting that military uses of space are not necessarily aggressive or hostile in nature, and therefore can be considered to be acceptable under the umbrella of <a href="https://spacesecuritylexicon.org/terminology/peaceful-use-and-exploration-of-outer-space-peaceful-purposes">peaceful purposes</a>. It is generally understood that the concept of militarization of outer space must be distinguished from the concept of <a href="https://spacesecuritylexicon.org/terminology/weaponization-of-outer-space">weaponization of outer space</a>. This distinction, however, is not universally accepted, as a number of States argue that, due to the nature of <a href="https://spacesecuritylexicon.org/common-definition/space-object">space objects</a> and the space environment, it is not possible to develop a meaningful definition of a <a href="https://spacesecuritylexicon.org/terminology/space-weapon">space weapon</a>. Moreover, it is important to note that there are languages which do not have a word for weaponization. In those instances, the word ‘militarization’ is often used to refer to both of these ideas, which can create further confusion.</div></div>

Militarization/Military Use Of Outer Space

<div><div>The term ‘monitoring’ can hold different meanings depending on the context. In the context of <a href="https://spacesecuritylexicon.org/terminology/verification">verification</a> for <a href="https://spacesecuritylexicon.org/terminology/space-security">space security</a>, it refers to the collection of various forms of data pertaining to States’ implementation of an agreement or conformity with guidelines in order to build a picture of all relevant activities in a State. This can be undertaken unilaterally using national technical means (NTM) and other forms of intelligence collection; cooperatively through some form of agreement to enhance transparency; or multilaterally, something often achieved through the work of international organizations. Notably, monitoring does not necessarily require States to accept specific legally binding obligations. In this sense, monitoring State activities can play a role beyond assisting in the verification process for legally binding agreements by fostering States’ adherence to their commitments. Monitoring is therefore an instrument that serves to build confidence and deter violations or irresponsible conduct.</div><div>In the context of radio frequency regulations, article 16 of the ITU Radio Regulations contains provisions related to international monitoring. National administrations agree to develop monitoring facilities and cooperate in the international monitoring system to help ensure efficient and economical radio-frequency spectrum use and eliminate promptly <a href="https://spacesecuritylexicon.org/terminology/harmful-interference">harmful interference</a>. The international monitoring system consists of nominated monitoring stations operated by national administrations, public or private entities, common monitoring services, or international organizations. The national administrations conduct, as far as they consider practicable, monitoring requested of them by other administrations or by the ITU.</div></div>

Monitoring

<div><div>Generally understood to mean the consequences or effects that are not directly caused by a specific action, but are nevertheless the product thereof. The concept of reverberating effects is commonly used in discussions relating to the use of force or armed attacks in the context of the conduct of hostilities. When conducting proportionality assessments prior to the use of force or armed attack, it is generally accepted that reverberating effects have to be considered to the degree in which they are reasonably foreseeable.</div></div>

Reverberating Effects

<div><div>Risk refers to the probability of an outcome having a negative effect on people, systems or assets. When used in the context of <a href="https://spacesecuritylexicon.org/terminology/space-security">space security</a>, it generally refers to the danger to the safety of a <a href="https://spacesecuritylexicon.org/common-definition/space-system">space system</a> or any of its components, that is to say, the possibility of accidental or unintended damage to space systems, or to people depending on the services provided by those systems. Risk is distinct from <a href="https://spacesecuritylexicon.org/terminology/threat">threat</a>, which refers to the danger to the security of a space system or any of its components, that is to say, the possibility of intended or intentional damage (involving agency, or done deliberately) to space systems, or to people depending on the services provided by those systems. It should be noted that outside of the space policy discourse, the term ‘risk’ does have security-related implications. The nuclear field is an example of this.</div><div></div></div>

Risk 

<div><div>Space safety is commonly understood to refer to measures aimed at preventing accidental or unintentional hazards to <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a>. These hazards can be natural, such as geomagnetic storms, or stem from human-made objects, such as the accidental malfunctioning of a <a href="https://spacesecuritylexicon.org/common-definition/satellite">satellite</a>, or collision with a piece of debris. Space safety measures therefore seek to mitigate any non-intentional damage to a space system. The possibility of such a damage is considered a <a href="https://spacesecuritylexicon.org/terminology/risk">risk</a> (as opposed to a <a href="https://spacesecuritylexicon.org/terminology/threat">threat</a>). Issues of space safety are generally understood to be a part of the broader topic of the peaceful uses of outer space, which is discussed at the Committee on Peaceful Uses of Outer Space (COPUOS) and under the purview of the General Assembly’s Fourth Committee.</div><div>Space safety is generally regarded as distinct from <a href="https://spacesecuritylexicon.org/terminology/space-security">space security</a>, although the two are interrelated, and can intersect and overlap. Certain languages do not differentiate between ‘safety’ and ‘security’, and therefore can generate confusion in distinguishing the two.</div></div>

Space Safety

<div><div>Space security is concerned with the relationship among <a href="https://spacesecuritylexicon.org/common-definition/space-object">space objects</a> and <a href="https://spacesecuritylexicon.org/common-definition/space-activities">activities</a>, and the maintenance of international peace and security, and disarmament, including the prevention of an arms race in outer space. Space security discussions fall under the purview of the United Nations disarmament bodies, including the Conference on Disarmament, First Committee, and the Disarmament Commission. Space security is also commonly understood to refer to measures designed to prevent deliberate harms to a <a href="https://spacesecuritylexicon.org/common-definition/space-system">space system</a>, including its component parts, from intended or intentional <a href="https://spacesecuritylexicon.org/terminology/threat">threats</a> undertaken by another actor.</div><div>Space security is distinct from <a href="https://spacesecuritylexicon.org/terminology/space-safety">space safety</a>, although the two are interrelated and can intersect and overlap. Certain languages do not differentiate between ‘safety’ and ‘security’, and therefore can generate confusion in distinguishing the two.</div><div>When discussing threats to space security, some actors have made the distinction between (military) danger and threat. The former precedes and can lead to the latter, and the latter refers to a situation closer to the use of force or the possibility of a conflict. More specifically, military danger refers to inter-State or intra-State relations characterized by the combination of factors, which may lead to a military threat under certain conditions. Military threat refers to inter-State or intra-State relations characterized by a real possibility of an outbreak of a military conflict between opposing sides and by a high degree of readiness of a given State (group of States) or separatist (terrorist) organizations to resort to military force (armed violence). This distinction, and this definition of military danger, is not universally accepted by the international community. </div></div>

Space Security

<div><div>Space sustainability is commonly understood to mean stakeholders’ ability to continue to be able to use and benefit from space. Space sustainability requires that space be kept safe and secure, so that stakeholders may be able to use, explore, and benefit from space “without discrimination of any kind, on a basis of equality and in accordance with international law” (article I of the OST). Space sustainability therefore seeks to preserve the usability of space.</div></div>

Space Sustainability

<div><div>There is no universally accepted definition of the term ‘space weapon’. Generally this term is used to refer to a capability or system used to deny, disrupt, degrade, damage or destroy or otherwise harm a system, infrastructure, person or group of people. Some consider that in order for a weapon to be classed as a space weapon, it has to be located in space, whereas others include non-space-based objects that can target space infrastructure. Moreover, there are some that consider that space weapons are those that target <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a>, including the <a href="https://spacesecuritylexicon.org/common-definition/ground-segment">ground</a> and <a href="https://spacesecuritylexicon.org/common-definition/data-links-link-segment">link segments</a>, as well as objects on the ground, sea or air.</div><div>There are certain States that have sought to establish a definition by which a space weapon is any outer <a href="https://spacesecuritylexicon.org/common-definition/space-object">space object</a> or its component produced or converted to eliminate, damage or disrupt normal functioning of objects in outer space, on the Earth’s surface or in the air, as well as to eliminate population, components of biosphere important to human existence, or to inflict damage to them by using any principles of physics. Others have criticized this definition as it does not include (i) objects not in space but which can be directed towards it to harm technology therein, and (ii) does not take into account that in some cases objects are capability-neutral and the intent of the actor is what determines whether they are used to harm another’s space object or disrupt their <a href="https://spacesecuritylexicon.org/common-definition/space-activities">space activities</a>. This is the case of <a href="https://spacesecuritylexicon.org/terminology/dual-use">dual-purpose</a> objects.</div></div>

Space Weapon

<div><div>When used in the context of <a href="https://spacesecuritylexicon.org/terminology/space-security">space security</a>, ‘threat’ generally refers to the danger to the security of a <a href="https://spacesecuritylexicon.org/common-definition/space-system">space system</a> or any of its components, that is to say, the possibility of intended or intentional damage (involving agency, or done in a deliberate manner) to space systems. Threat is distinct from <a href="https://spacesecuritylexicon.org/terminology/risk">risk</a>, which refers to the danger to the safety of a space system or any of its components, that is to say, the possibility of accidental or unintended damage to space systems. The identification of threats is not a straightforward task, as threat perception can be subjective in nature, due to the diverse range of actors’ and stakeholders’ interests and views of what can constitute a threat, and the fact that globally <a href="https://spacesecuritylexicon.org/common-definition/space-situational-awareness-ssa">SSA</a> and <a href="https://spacesecuritylexicon.org/common-definition/space-domain-awareness-sda">SDA</a> are not perfect tools to identify and address threats.</div></div>

Threat

<div><div>Verification refers to the process of collecting and assessing data with a view to informing judgements of a State’s compliance with its treaty obligations. The primary goal of verification in this sense is not necessarily to detect all violations of any agreement. Rather, the objective is to foster mutual transparency and confidence between States party to an agreement and to deter violations by increasing the cost and difficulty of undertaking non-compliant activities. However, it is generally expected that an effective verification regime should be able to detect ‘significant’ violations of an agreement before such activities threaten the core security objectives of the States concerned.</div><div>The process of verification typically entails three phases: first, <a href="https://spacesecuritylexicon.org/terminology/monitoring">monitoring</a> the activities of the parties to an agreement; second, undertaking technical analysis of information derived from monitoring; and third, drawing from the first two steps to reach a judgement as to whether a party is in compliance with its obligations.</div></div>

Verification

<div><div>There is no universally accepted definition of <a href="https://spacesecuritylexicon.org/terminology/space-weapon">space weapon</a>; however, weaponization of outer space generally refers to the proliferation, testing, deployment and use of weapons or <a href="https://spacesecuritylexicon.org/terminology/counterspace-capabilities">counterspace capabilities</a> located in or directed towards space or <a href="https://spacesecuritylexicon.org/common-definition/space-system">space systems</a>. The term itself is also not universally accepted, as it does not readily translate into all languages. Moreover, in some instances the word ‘<a href="https://spacesecuritylexicon.org/terminology/militarization-military-use-of-outer-space">militarization</a>’ is used to refer to both military activities in space and to weaponization of space.</div></div>

Terminology Used In Space Policy Discussions

Counterspace capabilities

Principles & Concepts of United Nations Space Treaties

Space Policy Discussions (Misc)

A Lexicon for Outer Space Security