Revista Brasileira de
Direito Aeronáutico e Espacial

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Prof. Yuri Kolossov*
Dmitry V. Gonchar**

*Professor of International Law, Moscow Institute of International Relations (University).
** Diretor da Seçao de Direito Internacional do Depto. Jurídico do Ministério das Relaçoes Exteriores da Federação Russa

The issue of establishing a clear legal definition of outer space and thus achieving delimitation of outer space and airspace is not a new one, in fact, it has been on the agenda of space-faring states, international organizations and the world community in general since the beginning of the space era. The significance of this issue is boosted by the fact that there exists no clear physical boundary between airspace and outer space as there exist no easily discernable technical attributes that would aid in establishing such a boundary. But what is the legal and political significance of trying to formulate a legal definition and delimitation of outer space today? One might argue, and it is quite often the case, that the existing system of International space Law is quite sufficient to regulate the activities of states in outer space and that the issue of delimitation is out-dated and impractical. To give a definitive answer to this question we must first examine the legal attributes of outer space and airspace and look at the issues that stand unresolved because of the fact that no such delimitation exists today.

The first and obvious difference in the legal regime of outer space and airspace is that, according to Article II of the Outer space treaty of 1967 outer space cannot be subjected to national appropriation, either by way of establishing national sovereignty over it, or by occupation or use. On the contrary, airspace contained within national boundaries of a state is subject to national sovereignty of that state and constitutes, subject to the relevant norms of international law, part of its national territory.

It can be thus stated that the absence of a clear-cut boundary between airspace and outer space undermines the very principle of national sovereignty of a state, because no state can define the limits of its territorial sovereignty, which, in turn, makes uncertain the exercise of that state’s jurisdiction. Such an uncertainty can lead to very practical problems and even, in some cases, can pose a threat to international peace and security.

One may point out a number of further differences in the legal regimes of outer space and airspace, based on the contemporary state of international law.

Airspace is divided into national and international parts while outer space is indivisible and is in its entirety in common use.

According to Article 4 of the 1967 Outer space treaty states-parties take upon themselves not to deplay nuclear weapons or any other weapons of mass destruction in Earth orbit, on any other stellar bodies or in outer space as a whole. There exists no such limitation in relation to airspace.

States have no obligation to explore and utilize airspace for the benefit and in the interests of all countries, as it is the case with outer space (Article 1 of the Outer space treaty). Furthermore, the exploration and utilization of outer space is the "common province" of all mankind.

States are not liable for damages caused by aircraft which are registered to and constitute the property of nonstate entities (such as companies and private citizens). On the other hand, States are internationally responsible for national activities in outer space whether or not such activities are carried out by state or non-state actors (Article 6 of the Outer Space Treaty). It is also responsible for the conformity of these activities with the said Treaty.

Furthermore, according to the provisions of the Convention on international liability for damage caused by space objects of 1972, and, in particular, its Article II, the launching state has absolute liability to compensate for the damages caused by its space objects on the surface of the Earth or to an aircraft in flight. On the other hand, according to Article III of the Liability convention, if damages to a space object of one state-party are caused by a space object of another state-party in any location other than the surface of the Earth the Launching State is only liable if such damages constitute fault of persons it is responsible for.

Thus, we see here that the absence of delimitation of airspace and outer space can lead to ambiguity concerning the limits of liability of a launching state and whether its liability must be deemed absolute or fault-based.

Further, according to Article III of the 1975 Registration Convention, the Secretary General of the United Nations is entrusted with keeping an international registry of objects, launched into Outer space, while no such provision exists for aircraft.

According to the UN Principles on the Remote Sensing of the Earth from outer space it is not necessary to obtain a permission form a state to conduct remote sensing of its territory from outer space, although there is the obligation to share primary data and information obtained from such sensing on a non-discriminatory basis and on the conditions of reasonable payment. Remote sensing from airspace is subject to international agreement between the interested parties, any activity conducted without such agreement would constitute an infraction on international law.

According to Article V of the Outer Space Treaty and relevant provisions of the 1968 Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space astronauts are regarded as envoys of mankind into outer space and states must render them all possible assistance in the event of an accident. Furthermore, astronauts must be promptly returned to the launching State in the event their craft has landed on foreign territory or in international waters, or in a region with a special legal regime (i.e. Antarctica). States are required to cooperate in that regard. No such obligation exists in relation to the crews of aircraft outside of the relevant international search and rescue agreements.

Given the differences in the legal regimes of airspace and outer space listed above and the potential for conflicting situations they may give rise to it is not surprising that the last 40 years have seen numerous theories of principles that might be used to develop a legal definition and delimitation of outer space. These may be classified into two broad categories - spatial concepts and functional concepts. In turn, spatial concepts may be else divided into two groups - those that propose to find a natural physical barrier between airspace and outer space or to establish the boundary in relation to the maximum flight altitude of aircraft. Others think that such a barrier is impossible to establish and a political solution to the issue must be found, i.e. to conclude an international treaty to this regard.

Among those who think that the best way to proceed to solve the issue of delimitation is to find a natural physical barrier between airspace and outer space. Several approaches may be pointed out:

* technical approach - the boundary between airspace and outer space is proposed to be established subject to the latest developments in aerospace technology. Again, this approach does not point to a fixed boundary between the two, subjecting it to the ever-rising level of flight altitude of the latest aircraft. This in practice limits the possibility of a state to exercise its sovereignty over its territory, and, on the other hand, gives new rise to theories of "effective sovereignty", which, in this case, violates the principle of sovereign equality of states, since the technological level of advancement in various countries will inevitably be different.

* orbital approach - first proposed by Uruguayan lawyers A.B.Araucho in 1958, it places the boarder between airspace and outer space at the lowest altitude that an artificial Earth satellite can effectively execute a full round orbit around the planet. It must be pointed out that this approach requires further development of some objective criteria concerning the aerodynamic shape of a satellite that would be used for such calculations as well as the conditions of the effects of the upper layers of the atmosphere upon its flight.

* jurisdictional line approach – proposed by Theodore von Karman and A.Hailey (US). They propose to set the height limit of a state’s jurisdiction at an altitude of approximately 83 km over sea level where a body travelling at a velocity of 7 km/sec is not affected by aerodynamic lifting force and is instead affected by centrifugal force in relation to the Earth.

There have been several possible approaches proposed on how to solve the issue using political means, i.e. establishing a boundary between airspace and outer space by way of international negotiations, through a norm of international law. Several factors have been taken into account, inter alia, the fact that the International Aviation Federation (IAF) has established rules according to which a space flight is considered a flight reaching the altitude of more than 100 km above sea-level. At the same time it has to be noted that it is considered impractical to launch satellites to an altitude less than 110 km due to too much atmospheric drag, which forces the satellite orbit to decay very quickly.

There have been proposals to declare a sui generis "intermediate" zone between the highest altitude of flight of aircraft and the lowest altitude of flight of satellites (i.e. approximately between 40 and 100 km). In this proposal, made by L.Nonchich (Austria), such a zone was supposed to have a special legal regime, analogous to the law of the sea "innocent passage" of space craft flying to or returning from Earth orbit.

On June 20 1979 the USSR has submitted a proposal on the issue of definition and delimitation of outer space for the consideration of the UN Committee on the peaceful uses of outer space (UN COPUOS). The Committee has been instructed to deliberate on the issue of delimitation in 1966, according to the UN General Assembly Resolution 2222 (XXI) of 19 December 1966, and since has been constantly on the agenda of the COPUOS Legal Subcommittee.

The Soviet proposal on delimitation contained 3 major elements:

1. Over-earth space higher than 100/110 km over sea-level will be deemed outer space.

2. The boundary between airspace and outer space shall be subject to negotiations between states and will be fixed by international treaty at a height of no more than 100/110 km above sea-level.

3. Space objects launched by one state shall enjoy the right to fly over the territory of another state at heights less than 100/110 km above sea-level for the purposes of getting into Earth orbit and returning to Earth, to the territory of the Launching State.

On March 30 1983 the Soviet delegation has submitted a working paper to the XXII Session of the UN COPUOS Legal Sub-committee which further clarified the 1979 delimitation proposal. The words "to the territory of the Launching State" have been deleted from paragraph 3 of the proposal, thus enabling returning spacecraft to "splash-down" in the world oceans. It will be further specified that such space objects should enjoy the right of "innocent overflight" over the territories of other states.

A few words must now be said about the so-called "functional" approach in the delimitation of outer space. Most advocates of this theory deem the over-Earth space indivisible and subject to two international legal regimes acting in parallel which regulate the outer space and aeronautical activities of states. They further believe that all over-Earth space should be covered by a unified legal regime, the rights and obligations of states according to which would vary in relation to the aims and functions of the spacecraft and aircraft. They suppose that, if the goal of the state was to launch a craft into Earth orbit such a craft, or object, would be covered by norms of international space Law. On the other hand, if the purpose of the launch was to effect a flight through the Earth’s atmosphere without the aim of reaching orbit, such a flight would be governed by norms of international aeronautical law.

Advocates of this approach further believe that outer space activities can be conducted by states safely and legally without establishing a clear-cut boundary between airspace and outer space, on the basis that up to now the absence of such a boundary has had no noticeable adverse effect on outer space activities of states.

The real danger in accepting such an approach, as we see it, is that many of the lawyers who favor it bring forward the idea that the principle of state sovereignty over its airspace has no absolute character and must be also regarded as "functional", or "relative".

Here we believe that state sovereignty over its airspace cannot be put into question. It is a serious infraction upon the universally acclaimed principle of international law that a state possesses full and complete sovereignty over its territory, comprising land, territorial waters and the airspace over them. The establishment of the legal regime of that airspace is the prerogative of that state, subject to relevant norms of international law. Attempts to undermine the principle of state sovereignty over airspace can have serious connotation, as they may be further used to undermine the concept of state sovereignty as a whole.

Furthermore, the functional concept stipulates that it will be always possible to differentiate between the goals of a given mission, whether they are to reach outer space and Earth orbit or to just simply fly to another destination on Earth. This belief is now being put into question, however, by the recent advances made in aerospace science and technology leading to the development of aerospace objects or vehicles. These objects will have the ability to undertake flight and maneuver in outer space and airspace and have the necessary propulsion plants and fuel reserves to effect multiple transit between Earth orbit and the upper layers of the atmosphere. So far we have seen only one type of aerospace object in existence – the US space shuttle, although it is common knowledge that such craft are in full-scale development in many countries of the world. In their case it would be impossible to predict what the aims of their mission would be, in fact, each mission could contain several goals, both in airspace and outer space. Accordingly, it would be impossible to say which legal regime such an object falls under at any given moment of time. This state of events creates, in our view, serious difficulties for most states which, in a few years from now may be faced, with the appearance of such craft over their territory. This may well cause international misunderstandings, if not potential for conflict.

Realizing potential difficulties that aerospace objects pose for the current international space law, the Russian Federation proposed in 1993 to distribute to all members of UN COPUOS a questionnaire concerning the definition, status and main attributes of aerospace objects. To-date, more than 40 countries have provided replies to that questionnaire. The analysis of those replies shows that the majority of COPUOS members favor the approach to the delimitation of outer space first proposed by the USSR in 1979 - the establishment of a treaty-based legal boundary between airspace and outer space with the special right of space objects to effect "innocent transit" through the airspace of other countries while proceeding to and returning from orbit. The Russian Federation will continue to support and promote this approach within the UN COPUOS Legal Sub-Committee until the successful resolution has been found, for the benefit of all mankind.



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2. A. Piradov, E. Vasilevskaia et al., Tendencies in development of space law. – Moscow, 1973

3. Pudovkin O. Contemporary issues of space law. – Moscow, 1999.

4. Kolosov Y., Zhukov G. et al., International space law. – Moscow, 1999.

5. Dictionary of International space law, under the editorship of V. Vereshchetin. – Moscow, 1992.

6. Treaties and Principles of the United Nations on Outer Space (A/AC.105/722). – Vienna, 1999

(Volta ao Sumário)

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