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Space Policy 22 (2006) 3–7

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Viewpoint

The need for air space and outer space demarcation

Alexandra Harrisa, Ray Harrisb,�

aDepartment of Law, University College London, Gower Street, London WC1E 6BT, UKbDepartment of Geography, University College London, Gower Street, London WC1E 6BT, UK

Abstract

This paper argues the need now to consider defining a vertical or spatial boundary between air space and outer space, which in turn

effectively means defining the extent of air law and space law. Technology changes in aircraft, spacecraft, positioning systems and remote

sensing, combined with the growth in the number of spacefaring nations, make the situation different from the early days of the space era

when it was assumed that a boundary would be defined at a future indeterminate date. This article describes the background to the

debates and the growing pressures of the questions of sovereignty concerning air and space law, and argues the case for a vertical or

spatial boundary rather than a functional one.

r 2005 Elsevier Ltd. All rights reserved.

1. Introduction

There are major differences in the legal realms of outerspace and air space and yet no agreed and defined legalboundary exists between the two. States are affected by thedifferent legal regimes of air and space law in many ways,most especially in relation to state sovereignty and nationaljurisdiction. As technology improves and there are craftthat can operate in both outer space and air space the lackof a legal definition will become a stumbling block. The USSpace Shuttle has for some years operated in both outerspace and air space: its landing approach explicitly uses theatmosphere to allow the Shuttle to glide to its landing site.The Pegasus launch system provides low cost entry to spaceby taking a rocket to a high point in the atmosphere fixedbeneath an aeroplane and then launching the rockethorizontally through the atmosphere on its way to outerspace. The concepts developed in Europe some years ago ofHotol and Hermes also foresaw a combination of anaeroplane and a space plane at different stages of amission. In addition, more states, such as Algeria, Nigeriaand Turkey, are launching space missions and so both thesize and the complexity of the challenge of defining a legal

e front matter r 2005 Elsevier Ltd. All rights reserved.

acepol.2005.11.004

ing author.

ess: r.harris@geog.ucl.ac.uk (R. Harris).

boundary between air space and outer space are becomingmore substantial.As Oduntan [1] argues, the principle of free and equal

utilisation of outer space must mean there is a limit tonational sovereignty where outer space begins. This articlewill examine the differences between the legal and policyframeworks of outer space and air space and why there isno present demarcation between the two. It will then go onto argue that demarcation is necessary to avoid disputes inrelation to state sovereignty, the use of weapons and publicexploitation. The paper concludes by recommending that avertical or spatial location boundary is preferable to afunctional demarcation: we argue that the establishment ofan easily determinable boundary above mean sea levelshould be the preferred route.An interesting case of confusion over the perception of

the scope or extent of air and space law can be seen in theproducts of the very high spatial resolution Earthobservation satellites such as Ikonos and Quickbird.Ikonos has a best spatial resolution of 1m and Quickbirdof 0.61m. The images from these satellites are comparableto those that can be obtained from aerial survey withaircraft [2]. The Earth observation satellites are subject tospace law (and also to the UN Principles on RemoteSensing [3,4]) and not to air law, even though there havebeen comments from some countries that national sover-eignty is infringed because of the high spatial resolution in

ARTICLE IN PRESSA. Harris, R. Harris / Space Policy 22 (2006) 3–74

the images obtained by the Ikonos and Quickbird satellites.At the Congress of the International Society of Photo-grammetry and Remote Sensing (ISPRS) held in Istanbul,Turkey in July 2004 there was debate over the access toinformation on the resources of Less EconomicallyDeveloped Countries (LEDCs) by Western nations whichown and operate very high resolution Earth observationsystems. The issues debated focused on privacy andsecurity of the sensed LEDCs, themes that were alsoaddressed in microcosm for North American Indian tribesat a conference in Maine in August 2004. The debate at theISPRS Congress was somewhat mitigated by the changingperceptions of Algeria, Brazil, China and Nigeria now thatthey have launched their own Earth observation satellites,in some cases as part of the Disaster ManagementConstellation (DMC). Satellites launched by LEDCs havea spatial resolution of about 30m which does not rival the1m of the very high resolution systems, but the history ofsatellite Earth observations has shown a persistentimprovement in spatial resolution at lower cost; withinthe next decade all countries should be able to afford Earthobservation technology that provides images comparableto those that can be obtained from aircraft platforms.

2. Air space and outer space

Air space is a highly regulated part of a state’s territoryand comes within national jurisdiction. This can be seen inArticle I of the International Convention relating to AirNavigation, Paris, 1919: ‘The High Contracting Partiesrecognise that every power has complete and exclusivesovereignty over the air space above its territory’. Theprinciple was also confirmed in Article I of the Conventionon International Civil Aviation, Chicago, 1944. Thereforestates have complete control over their air space and othercountries can only infringe upon that air space after prioragreement by way of treaty or other internationallyrecognised measures.

Outer space by contrast is an area outside nationalterritorial sovereignty as it is an international area underArticle II of the Outer Space Treaty.1 The application ofterritorial sovereignty in outer space by states is unequi-vocally prevented by international law. Although there issome jurisdiction in outer space this is jurisdiction ofobjects launched into space, not over outer space itself. Anexample of this is Article VIII of the Outer Space Treaty,which confers jurisdiction and control on the state party onwhose registry an object is launched into outer space. Outerspace is a public space, as Article I of the Outer SpaceTreaty calls it the ‘province of all mankind’. Furthermore,Article XI(I) of the Moon Agreement provides that the‘moon and its natural resources are the common heritageof mankind’.2

1Treaty on Principles Governing the Activities of States in the

Exploration and Use of Outer Space, including the Moon and Other

Celestial Bodies (hereafter the Outer Space Treaty); 6 ILM 386 (1967).

Two different registries exist for aircraft and spaceobjects and this itself presupposes two different sets offunctions, activities or modes of operation for them as well.Therefore, it seems important to determine where nationalsovereignty ends and where the province of all mankindbegins, and yet the demarcation problem is still an openquestion in both air and space law.Of the two types of law, air law is the oldest and does not

contain a fixed definition of the vertical extent of air space.There is no precise definition of where the boundary of airspace lies in relation to outer space. The questions ofboundary definitions have only taken on meaning andimportance, as the lines between air and space law havebecome blurred [1]. Until relatively recently aircraft flew inair spaces and states had control over the whole operation.Spacecraft operated in outer space and had little impact onstates so the definition of outer space was not necessary. Itwas assumed that a customary law was developing wherebyany object in orbit was in space and that was enough forthe time being [5].

3. Perspectives on the problem

In the early work at the UN Committee on the PeacefulUses of Outer Space the delegate from the USSRconcluded ‘it is not possible at the present time to identifyscientific or technical criteria which would permit adefinition of outer space’. Here the perceived problemwas a need for a defining criterion that simply did not existat that time, such as a limit as to how high aeroplanescould fly or how low spacecraft could orbit. It appears,however, that the current lack of delimitation is not theresult of disputes over how the boundary should bedefined. There is a widespread, although not universal,assumption that there will be a necessary definitioneventually but no action is needed to make a definitionnow. For example, in 1959 Jessup and Taubenfeld [6]assumed a vertical air space limit to territorial sovereigntywould be agreed at some point and theorised that eventualpractical necessities would lead to its definition. Thereappears to be a broad consensus that a delimitation willsimply arise at some date without indicating when that datewould occur.The USA argued in 1987 that there is no usefulness to a

demarcation because outer space has no physicallyobservable landmarks and most states are incapable ofaccurately determining the altitude of space objects andtherefore are not in a position to monitor any agreedaltitude boundary.3 This argument is now out of datebecause new technology allows for precise positioning ofsatellites and aircraft, either by the general-purpose GlobalPositioning System (GPS) or by specific equipment such as

2Agreement Governing the Activities of States on the Moon and other

Celestial Bodies (1979) UN doc A/34/664.3US reaction to a working paper submitted by the USSR in 1987, in

Oduntan [1].

ARTICLE IN PRESSA. Harris, R. Harris / Space Policy 22 (2006) 3–7 5

the Doris instrument flown on ESA’s Envisat for precisepositioning of the spacecraft. GPS equipment is nowcheaply and widely available and so can be fitted to allaircraft, thereby making the argument of being unable toidentify a precise location in the atmosphere no longertenable. Most satellites will be in outer space and it istherefore only those craft that may encroach upon a state’sterritory that will have to be monitored. The establishmentof a boundary will actually promote certainty as towhich craft need precise positioning. Also, it is beneficialfor states to develop or exploit technology to measurealtitude of craft if the purpose is to protect territorialintegrity.

It may be argued there is no current delimitation becauseit has not yet been necessary and space and air law havehappily existed without it. Commentators suggest that theabsence of an agreement has not yet led to internationaldisputes and appears unlikely to do so in the future. Theyargue that, if a boundary is set now, it may easily be toohigh or too low because we have not as yet developed thetechnology to let us make the delimitation. There is also theview that it is a political and not a legal issue, as the mainproblem with the lack of definition is that nationalterritories are not defined. The legal definition shouldtherefore come from political agreement, not the other wayround.

The reasons for a lack of demarcation do appear to bepolitical and may rest on the fact that absence of a preciseboundary is advantageous to the dominant interests ininternational space exploration. The calls in favour ofdemarcation tend to come from states that lack a capabilityto engage in large-scale space activities. This was the case inthe Bogota Declaration of 1976.4 In this declaration theparticipating equatorial states argued that there was nodeclaration between jurisdiction in outer space and theirnational jurisdiction, and so they should have control overthe geostationary orbits above their countries [1]. Theproposal was rejected by the international community.

At present, most states appear to agree on the need toestablish a demarcation at some date in the future, but themain calls to do so come from the less-developed countrieswhich have concerns over their national jurisdiction andsovereignty, rather than from the Western nations, whichhave economic interests in space. Nigeria’s call in 1990 for‘a clear definition and delimitation of the air space ofvarious countries as distinct from outer space’5 is evidenceof this case. This call was backed by many non-spacefaringnations that were concerned about state sovereignty, notabout their economic interests in space, although it isworth noting that since 1990 Nigeria has joined the spaceclub by launching its own DMC satellite.

4Declaration of the First Meeting of Equatorial Countries 1976, the

Bogota Declaration on the Geostationary Orbit.5Address to the 33rd session of the UN Committee on the Peaceful Uses

of Outer Space, June 1990.

4. Sovereignty

There are significant legal differences between air spaceand outer space and these differences affect the nationalsovereignty of states and the fields of activity. Statesovereignty and national territory are highly protected inother areas of Public International Law, such as StateImmunity and Use of Force [7], and it may be questionedwhy the issue is so readily ignored in relation to space law.A possible answer is that technology is not yet a threat tostate sovereignty. When more craft can easily movebetween the Earth’s atmosphere and outer space, andwhen many countries and indeed private companies canexploit this capability, then the boundary will become aconcern. Developments in air-breathing rocket technologypoint in this direction. It is highly desirable for a boundaryto be defined now because the eventual practical necessitieswhich Jessup and Taubenfeld [6] predicted are on thehorizon.The delimitation also has implications for international

law. As Prescott notes [8], a boundary would ‘mark theposition where international rights are determined andobligations assumed’. Therefore there are issues not onlyfor state sovereignty but also for the internationalcommunity concerning where the province of all mankindstarts. It is useful to know at what point there can be theexercise of international power over international spaces.An agreed boundary is also necessary for the exploita-

tion of electronic resources. As seen in the BogotaDeclaration the ownership of the geostationary orbit, andindeed other orbits such as the near-polar orbit, couldbecome a sovereignty question. Although the question ofsovereignty over the geostationary orbit was answered bycustomary international law because there can be no claimto sovereignty in outer space, similar questions could ariseover the allocation of broadcasting and communicationswavelengths. Current technology means that broadcastscan use outer space or air space and this technology willonly become more complex in the future. The definition ofthe boundary of air and space law will be a necessity,enabling states to determine whether they have jurisdictionto allocate broadcasting wavelengths or not.Article IV(para 1) of the Outer Space Treaty states that:

State parties to the Treaty undertake not to place inorbit around the Earth any object carrying nuclearweapons or any other kinds of weapons of massdestruction, install such weapons on celestial bodies,or station such weapons in outer space in any othermanner.

This is the only limit on the military use of the void ofouter space, although Article VI(para 2) restricts the use ofthe Moon and other celestial bodies to non-aggressivepurposes. There is therefore a limited demilitarisation ofspace and a complete demilitarisation of celestial bodies.Although it may be safely assumed that celestial bodies arein outer space, the questions of weapons of mass

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6Convention on International Civil Aviation, Chicago, 1944, Annex 13.

A. Harris, R. Harris / Space Policy 22 (2006) 3–76

destruction and nuclear weapons have an air/spaceboundary element to them. There is nothing preventingthe stationing of such dangerous weapons in a state’s ownterritory—the prohibition merely applies to craft orbitingthe Earth. Without the definition between air space andouter space, this could be exploited by using technologywhich could be placed high enough in the atmosphere, oreven above the atmosphere, to cause a major threat tointernational security. This is an illustration of where it isnecessary that outer space be defined so that this potentialaction can be prevented. There may also be a question ofthe use of force in outer space: where is the limit of a state’sterritory for attack and where does an internationalpeaceful area start?

There are practical issues to the delimitation of outer spaceand air space. Spacecraft using nuclear fuels may beprohibited from discharging waste in the atmosphere,however thin the atmospheric layer. Also, there is a need tohave control over the launching and return of spacecraft asthere needs to be definition of the point at which jurisdictionalsovereignty of a state to say they do not want a craft in theirjurisdiction applies. This may apply to the right of self-defence against an attacking state and the definition of whena right to self-defence can be exercised against a state whosecraft is high in the atmosphere above another state.

An agreement of the boundary may well encourage andassure the development of space technology. If agreementis reached now, before the issues become contentious, itwill enforce the settled nature of space technology; leavingthe issue to be decided at a later date is far more likely tolead to increased tension.

The mere fact that until now there has been nodelimitation of the air and space boundary does not meanthat one is not necessary. There may not have been anecessity at the start of the Space Age because of the easydistinction between air and space law, and because therewere so few nations capable of launching spacecraft. Asthis distinction is closing in and the lines are becomingmore blurred, and now that more nations have launchedtheir own spacecraft, it is becoming essential that aboundary be chosen. Without it, there are many potentialproblems such as state jurisdiction and military capabilitieswhich, if not dealt with now, are likely to become a majorsource of friction on the international stage.

5. Functional or spatial demarcation?

Although Gardiner [9] describes the functional approachto air and space demarcation as the most promising, thereare major flaws in this argument; we believe that vertical orspatial demarcation is the most effective conclusion.Vertical or spatial demarcation is the establishment of aneasily determinable boundary at a certain altitude abovemean sea level. Functional demarcation is where differentfunctions delimit different spaces: where aircraft fly isairspace and where space objects operate is outer space.The functional approach also links to the definition of

aircraft in the Annexes to the Chicago Convention: ‘Anymachine that can derive support in the atmosphere fromthe reactions of the air other than the reactions of the airagainst the earth’s surface.6 There are, however, manyproblems with the functional approach, not least theexample that Gardiner himself gives of the US SpaceShuttle. This operates a rocket launch on the way to beingplaced in orbit above the Earth, and is therefore aspacecraft, but on the way back to the Earth’s surface ituses aerodynamic lift, and would be classed as an aircraft.The problem here is obvious—when is the Space Shuttlegoverned by space law and when is it governed by air law?The functional approach only covers half the problem of

demarcation as it classifies outer space not as a place but asa focus of activities. This does not take into account thefact that outer space is a physical place, not just a placewhere activities that are ultimately based on earth arecarried out. Outer space must begin somewhere, but wecannot let technological capability decide at any one timehow far into the atmosphere mankind can go and still callit national sovereignty. There needs to be a fixed boundary,not one changeable by technological advances and this canbe provided by a spatial demarcation. Oduntan [1] notesthat space is neither solely technology nor solely policy, buta zone where there is a complex interplay of pressures: ‘Thecontinuing partnership of law, politics, science andtechnology in respect of space activities needs to be furtherconsolidated in the interests of mankind’. A vertical orspatial demarcation is thus necessary as there needs to be adefinite boundary between air and space law. Thedemarcation line must be sensitive to technologicaladvances and the possibilities of regulating nationaljurisdiction—it must not hamper space technology andmust not be so high that national air space cannot beregulated. It must also not be so low that states aredeprived of part of their territory or of regulating over-flight activities which affect them. As the demarcation willaffect every state in the world, there must be internationalagreement before a boundary is decided upon.

6. Conclusion

Demarcation is vital not only for state sovereignty andjurisdiction, but also for issues of international stabilityand the growth of space technology. The complexity of theissues involved combined with the knowledge of futuretechnological developments give urgency to the view thatthe issue should be dealt with now rather than at someindeterminate point in the future.

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