The legal status of space debris

Considering the growing problem of space debris, sometimes referred to as space waste or space garbage, let’s study the legal status of space debris, and ask ourselves, for this new space law article on Space Legal Issues, the following question: are space debris space objects? From year to year, space experts, which are seeing a rapid worsening of the situation in orbit, are worrying about space debris.

Initially, the term space debris referred to the natural debris found in the Solar System: asteroids, comets, and meteoroids. A typical dictionary definition of debris is “the remains of something broken down or destroyed”. To this is often added “ruins, fragments, rubbish”. A more geological orientation may elicit “an accumulation of fragments of rocks”.

However, with the development of space activities, the term also refers to the debris from the mass of defunct, artificially created objects in space, especially Earth orbit. These include old satellites and spent rocket stages, as well as the fragments from their disintegration and collisions. Are space debris space objects? The 1967 Outer Space Treaty doesn’t really provide a definition for “object launched into outer space” other than an indication in Article VIII that it includes the “component parts” of the “object launched into outer space”.

Could we use the Convention on International Liability for Damage Caused by Space Objects (entered into force on September 1, 1972) if a space debris was to hit and damage a functioning satellite? Could we use the Convention on Registration of Objects Launched into Outer Space (entered into force on September 15, 1976) to keep track of space debris and launching States that still have jurisdiction and control over the space (object) debris? What is the legal status of space debris?

Space debris

In studying the legal status of space debris, let’s mention that in almost sixty years of space activities, more than five thousand launches have resulted in some forty-three thousand tracked objects in orbit, of which about twenty-three thousand remain in space and are regularly tracked by the United States Space Surveillance Network and maintained in their catalogue, which covers objects larger than about five to ten centimetres in Low Earth Orbit (LEO) and thirty centimetres to one meter at Geostationary Earth Orbit (GEO). Only a small fraction are operational satellites. This large amount of space hardware has a total mass of more than seven thousand and five hundred tonnes (the mass of the Eiffel Tower).

Space debris, known as orbital debris, space junk, space waste, space trash, space litter or space garbage, is, according to the European Space Agency (ESA), defined as all non-functional, human-made objects, including fragments and elements thereof, in Earth orbit or re-entering into Earth’s atmosphere. Concerning the legal status of space debris, human-made space debris dominates over the natural meteoroid environment, except around millimetre sizes. All human-made space objects result from the about thousands of launches conducted since the start of the Space Age. The majority of the catalogued objects, however, originate from in-orbit break-ups as well as few in-orbit collisions.

Routine ground-based radar and optical measurements performed by the space surveillance systems of many countries (including the United States of America) allow the tracking and cataloguing of objects orbiting around the Earth. Each of these catalogued objects has a known orbit and many can be traced back to a launch event − to a unique owner. Ground-based search radars can detect smaller objects, down to a centimetre or less in size. Such objects, however, can generally not be correlated with specific launch events, nor can their orbits be determined with sufficient accuracy to be predictable in future.

About twenty-four per cent of the catalogued objects are satellites (less than a third of which are operational), and about eighteen per cent are upper stages and mission-related objects such as launch adaptors and lens covers. More than two hundred and ninety in-orbit fragmentation events have been recorded since 1961. Only a few were collisions (fewer than ten accidental and intentional events); the majority of the events were explosions of spacecraft and upper stages.

The main cause of in-orbit explosions is related to residual fuel that remains in tanks or fuel lines, or other remaining energy sources, that remain on board once a rocket stage or satellite has been discarded in Earth orbit. Over time, the harsh space environment can reduce the mechanical integrity of external and internal parts, leading to leaks and/or mixing of fuel components, which could trigger self-­ignition. The resulting explosion can destroy the object and spread its mass across numerous fragments with a wide spectrum of masses and imparted velocities.

The first-ever accidental in-orbit collision between two satellites occurred on February 10, 2009, at an altitude of roughly eight hundred kilometres above sea level. A privately owned American communication satellite, Iridium 33, and a Russian military satellite, Kosmos 2251, collided. Both satellites were destroyed, and more than two thousand and three hundred trackable fragments were generated, some of which have since re-entered (that is, decayed and re-entered the atmosphere, where they have burned up). That is why it is important to study the legal status of space debris.

The Kessler syndrome

The Kessler syndrome is a theory proposed by NASA scientist Donald J. Kessler in 1978, used to describe a self-sustaining cascading collision of space debris in LEO. In an article published on June 1, 1978 in the American Journal of Geophysical Research, a peer-reviewed – the evaluation of work by one or more people with similar competences as the producers of the work – scientific journal, containing original research on the physical, chemical, and biological processes that contribute to the understanding of the Earth, Sun, and Solar System, authors Donald J. Kessler and Burton G. Cour-Palais, two NASA experts, identified the risk of an exponential increase in the number of space debris or orbital debris under the effect of mutual collisions. The two authors believed that a belt formed by these objects or fragments of objects around the Earth would soon form. Eventually threatening space activities, this phenomenon will be popularised a few years later under the name of Kessler syndrome.

The Kessler syndrome, also called the Kessler effect, collisional cascading or ablation cascade, is a scenario in which the density of objects in Low Earth Orbit (LEO) is high enough that collisions between objects could cause a cascade where each collision generates space debris that increases the likelihood of further collisions. One implication is that the distribution of debris in orbit could render space activities and the use of satellites in specific orbital ranges impractical for many generations. Every satellite, space probe, and manned mission has the potential to produce space debris. A cascading Kessler syndrome becomes more likely as satellites in orbit increase in number. The most commonly used orbits for both manned and unmanned space vehicles are Low Earth Orbit (LEO). Clearly, the number of space debris that naturally falls back into the atmosphere is less than the number of those generated by the collision of existing space debris. Even if all space activity and launch were halted tomorrow, the debris population would continue to increase exponentially, leading to a situation in which some orbits would become impassable in the long run.

As the number of artificial satellites in earth orbit increases, the probability of collisions between satellites also increases. Satellite collisions would produce orbiting fragments, each of which would increase the probability of further collisions, leading to the growth of a belt of debris around the earth. This process parallels certain theories concerning the growth of the asteroid belt. The debris flux in such an earth-orbiting belt could exceed the natural meteoroid flux, affecting future spacecraft designs. A mathematical model was used to predict the rate at which such a belt might form. Under certain conditions the belt could begin to form within this century and could be a significant problem during the next century. The possibility that numerous unobserved fragments already exist from spacecraft explosions would decrease this time interval. However, early implementation of specialized launch constraints and operational procedures could significantly delay the formation of the belt” – Collision frequency of artificial satellites: The creation of a debris belt, Journal of Geophysical Research, Volume 83, Issue A6, p. 2637-2646 (1978).

Space debris by the numbers (2019)

Number of rocket launches since the start of the space age in 1957: about five thousand four hundred and fifty (excluding failures).

Number of satellites these rocket launches have placed into Earth orbit: about eight thousand nine hundred and fifty.

Number of these still in outer space: about five thousand.

Number of these still functioning: about one thousand nine hundred and fifty.

Number of debris objects regularly tracked by the United States Space Surveillance Network (which detects, tracks, catalogues and identifies artificial objects orbiting Earth) and maintained in their catalogue: about twenty-two thousand and three hundred.

Estimated number of break-ups, explosions, collisions, or anomalous events resulting in fragmentation: more than five hundred.

Total mass of all space objects in Earth orbit: more than eight thousand and four hundred tonnes.

Number of debris estimated (by statistical models) to be in orbit: thirty-four thousand objects larger than ten centimetres. Nine hundred thousand objects from one centimetre to ten centimetres. One hundred and twenty eight million objects from one millimetre to one centimetre.

Space objects and their legal status

The term Object in reference to outer space was first used in 1961 in General Assembly Resolution 1721 (XVI) titled International cooperation in the peaceful uses of outer space to describe any object launched by States into outer space. Professor Bin Cheng, a world authority on International Air and Space Law, has noted that members of the COPUOS during negotiations over the space treaties treated spacecraft and space vehicles as synonymous terms. The Space Object can be considered as the “conventional launcher (ELV)”, the “reusable launcher (RLV)”, the “satellite”, the “orbital station”, the “probe”, the “impactor”, the “space telescope”, the “International Space Station (ISS)”… As Professors Diederiks-Verschoor and Kopal wrote in An Introduction to Space Law, the term space object “is indeed the commonly used expression, but it must always be borne in mind that its exact meaning is still not quite clear”.

An object is defined by the Oxford English Dictionary as “A material thing that can be seen and touched”. The five Onusian treaties don’t use the term satellite, instead opting for “object launched into outer space” in the 1967 Outer Space Treaty or “space object” in the 1972 Liability Convention and the 1976 Registration Convention. The 1967 Outer Space Treaty doesn’t really provide a definition for “object launched into outer space” other than an indication in Article VIII that it includes the “component parts” of the “object launched into outer space”. To add to the mix, Article V of the 1967 Outer Space Treaty uses the term “space vehicle” and the 1968 Rescue Agreement (which is essentially an elaboration of Article V of the OST) uses the term “spacecraft”. A good definition is given by Professor Hobe who write that a “space object is a human made object launched into outer space intended to be used in (as opposed to merely transit through) outer space”.

Let’s remember that “A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose”, article 31 of the Vienna Convention on the Law of Treaties of 1969. In addition, “Recourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to confirm the meaning resulting from the application of article 31, or to determine the meaning when the interpretation according to article 31: (a) leaves the meaning ambiguous or obscure; or (b) leads to a result which is manifestly absurd or unreasonable”, article 32 of the Vienna Convention on the Law of Treaties of 1969.

Let’s recall that a space object causing damage triggers international third-party liability under the Convention on International Liability for Damage Caused by Space Objects (entered into force in September 1972). Article I (d) of which enounces that “the term space object includes component parts of a space object as well as its launch vehicle and parts thereof”. Its Article II adds that “A launching State shall be absolutely liable to pay compensation for damage caused by its space object on the surface of the Earth or to aircraft in flight”.

A space object requires, thanks to the Convention on Registration of Objects Launched into Outer Space (entered into force in September 1976), registration. Article II of which states that “When a space object is launched into Earth orbit or beyond, the launching State shall 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”.

Finally, the term space object effectively triggers application of much of both the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (entered into force in October 1967) and the Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space (entered into force in December 1968). Article VII of the first declares that “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”.

Article 5 of the latter states that “1. Each Contracting Party which receives information or discovers that a space object or its component parts has returned to Earth in territory under its jurisdiction or on the high seas or in any other place not under the jurisdiction of any State, shall notify the launching authority and the Secretary-General of the United Nations. 2. Each Contracting Party having jurisdiction over the territory on which a space object or its component parts has been discovered shall, upon the request of the launching authority and with assistance from that authority if requested, take such steps as it finds practicable to recover the object or component parts. 3. Upon request of the launching authority, objects launched into outer space or their component parts found beyond the territorial limits of the launching authority shall be returned to or held at the disposal of representatives of the launching authority, which shall, upon request, furnish identifying data prior to their return”.

The 1967 Outer Space Treaty doesn’t really provide a definition for “object launched into outer space” other than an indication in Article VIII that it includes the “component parts” of the “object launched into outer space”. It states 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. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or 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, which shall, upon request, furnish identifying data prior to their return”. We’ll conclude with the definition given by Professor Hobe who wrote that a “space object is a human made object launched into outer space intended to be used in (as opposed to merely transit through) outer space”.

The legal status of space debris

Article VII of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (entered into force on October 10, 1967) states that “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”.

Article VIII of the aforementioned Treaty adds 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. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or 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, which shall, upon request, furnish identifying data prior to their return”.

As a conclusion on the legal status of space debris, we could consider that these “objects” are space objects since they are “component parts” of “objects launched into outer space”. The distinction should be made between fragments, debris and wrecks. Some rules have to be established as soon as possible in order to limit space debris. This is what we can say concerning the legal status of space debris.

Let’s note that the Whipple shield or Whipple bumper, invented by Fred Lawrence Whipple (November 5, 1906 – August 30, 2004), an American astronomer, is a type of hyper-velocity impact shield used to protect crewed and uncrewed spacecraft from collisions with micro-meteoroids and orbital debris whose velocities generally range between three and eighteen kilometres per second. There are over one hundred shield configurations on the International Space Station (ISS) alone, with higher-risk areas having better shielding.