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WK2/SS2 in flight
Commercial spaceflight activities, like the upcoming suborbital spaceflights of Virgin Galactic’s SpaceShipTwo, could lead to a refinement of what the definition of “outer space” is. (credit: J. Foust)

Could commercial space help define and delimitate the boundaries of outer space?

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Of the many legal and technical issues surrounding outer space activities, perhaps none is more elusive than defining where outer space begins or, more specifically, the delimitation of where atmospheric flight ends and the lower end of outer space and spaceflight begins. This issue, aside from being a legal issue, is also a political and national security issue that implicates the sovereign rights of nations.

While the debate over the delimitation of outer space is still unresolved, the advent of commercial spaceflight, in particular suborbital flights, may help to clarify the ambiguity and lead to a definition of the delineation of the lower limits of outer space and airspace, if not in law then in practice. To understand the issue it is helpful to be familiar with some of the origins of the issues, in particular with the United States, as well as its present status within the scope of national sovereignty and security.

The Eisenhower Administration and the position of the United States

Eight months after the launch of the world’s first artificial satellite, Sputnik 1, and the subsequent launch of Explorer 1 some three months later, the National Security Council under the Eisenhower Administration produced a draft document titled “U.S. Policy of Outer Space.”1 The purpose of the policy statement was to address to the fullest extent possible the implications of the new arena of outer space activities, with emphasis on national security. It noted that the USSR at that time surpassed the United States in outer space activities and, if that lead was maintained, it could affect the status of the United States geopolitically. It also argued that the security of the United States could be compromised if the USSR first achieved a significant military capability in outer space.

The Soviet Union tried to justify it by claiming that Sputnik 1 had not violated any other nation’s sovereign territory since Sputnik 1 had not flown over any nation’s territory but, instead, those territories had passed under Sputnik 1.

This policy statement in part recognized the problem of defining outer space, noting that the term has no generally accepted precise definition while the term “air space” has been dealt with internationally. The policy statement also recognized that although successful orbiting of satellites raised questions of national sovereignty ad colelum and to the doctrine of freedom of space, the United States did not recognize any upper limit to sovereignty.

Interestingly, before the launch of Sputnik 1, the Soviet Union asserted sovereignty of outer space above their territory. However, the launch of Sputnik 1 contradicted this theory of sovereignty. The Soviet Union tried to justify it by claiming that Sputnik 1 had not violated any other nation’s sovereign territory since Sputnik 1 had not flown over any nation’s territory but, instead, those territories had passed under Sputnik 1. This claim was quickly dropped, as was their prior theory of national sovereignty over outer space.2

Because of the ambiguity of defining where “air space” ends and “outer space” begins, the policy statement recommended that the United States take no public position on the definition of outer space, so as to maintain flexibility in international negotiations with respect to the uses of outer space as well as in anticipation of an international control agreement. Furthermore, taking no public position would preserve flexibility with regard to freedom of actions related to military uses of outer space.

However, the statement also recognized that the issue of rights in outer space was certain to be a topic at the UN General Assembly in September 1958, as well as in international dialogues after the activities of the International Geophysical Year. Therefore, it would be prudent for the United States to have a prepared position on the definition of outer space, to which the policy statement formally recognized as being divided into two regions: “air space” and “outer space,” where “outer space” is regarded as adjacent to “air space” with the lower limit of “outer space” being the upper limit of “air space.”

This public stance has changed little and, in fact, the National Aeronautics and Space Act of 1958 appears to mirror this position in that implies that the earth’s atmosphere equates with the notion of “airspace” whereas conversely outer space is the area outside of the Earth’s atmosphere.3 Moreover, even though COPUOS has occasionally raised the issue as a legal matter since 1959, the public position of the United States has remained relatively consistent. This is demonstrated at the 40th Session of COPUOS in Vienna in 2001 where, directly addressing the subject, the delegation of the United States maintained that:

“With respect to the question of the definition and delimitation of outer space, we have examined this issue carefully and have listened to the various statements delivered at this session. Our position continues to be that defining or delimiting outer space is not necessary. No legal or practical problems have arisen in the absence of such a definition. On the contrary, the differing legal regimes applicable in respect of airspace and outer space have operated well in their respective spheres. The lack of a definition or delimitation of outer space has not impeded the development of activities in either sphere.

We have not been persuaded by the reasons put forth for undertaking such a definition or delimitation. For example, some delegations support the notion of such a definition for its own sake. But without a practical problem to address, undertaking such a definition would be a risky exercise, as explained more fully below. Other delegations suggest that a definition or delimitation is somehow necessary to safeguard the sovereignty of states. However, we are aware of no issue of state sovereignty that would be solved by defining outer space.”4

Conversely, both China and Russia take a stance opposite to the United States on the matter. Both China and Russia publically agree that the issue needs to be addressed; however, they both state that the issue should be addressed through a legally-binding treaty. Russia’s perspective in particular was stated earlier this year in response to a series of questions posed by COPOUS to its members in 2006 concerning the matter. Specifically, Russia takes the position that a delimitation of outer space can only be established by a legally-binding treaty, which establishes either a physical boundary or agreed legal definition.

Regulation of outer space and airspace is based on the nature of the activities versus distance from the Earth.

This is not a new position for Russia or the former Soviet Union. In 1979, 1983, and 1987 the USSR proposed a legally-binding agreement that would establish a boundary between outer space and airspace that met certain conditions. The proposed boundary would be at an altitude not exceeding 100–110 kilometers above sea level.5 However, a legally-binding treaty addressing delimitation is not likely given the current geopolitical environment.

The international legal approach to delimitation

Delimitation under international law takes two basic forms: functional and spatial. The functional approach views outer space and airspace as a single above-ground space that does not require delimitation. Therefore, regulation of outer space and airspace is based on the nature of the activities versus distance from the Earth.

For example, a satellite in transit would be considered generally traveling through what is accepted as “outer space” up and until it reenters the atmosphere. On the other hand, a high-altitude balloon or fixed-wing aircraft, which by their nature are limited to atmospheric flights, would be considered traversing “air space” even though they may be able to reach the lower limits of “outer space.” This approach can be expressly affected by advances in technology and engineering. For example, the nature of the Space Shuttle system allowed it to function as both a spacecraft in “outer space” and function as an aircraft/glider in airspace even though it was technically considered a spacecraft.

Conversely, the spatial approach focuses on the main differences between the legal regimes of outer space and airspace. There is also the follow-on need for a definition of the spatial limitations that determine the extent of application of the principle of freedom to explore space on the one hand, and that of state sovereignty over national airspace on the other. Thus, certain laws govern travel through what is internationally recognized as “air space”, but when a craft reaches a specified spatial distance that delimitates the boundary of “outer space”, a different set of international regulations apply. Notably, the drawback of the spatial approach is that solar activity can cause the atmosphere to expand and contract to the extent that a line of demarcation may not be consistently valid.

National space laws

In an article written in 1998, space law professor Frans von der Dunk postulates that national space legislation, especially in the instance of major space actors, constitutes state practice and opinio juris relevant to the formation of customary international law, and may in fact provide the basis for forming a rule for the borderline of outer space.6 Professor von der Dunk in course analyzes five domestic space laws from different nations, including the United States, Russia, and Australia, to determine to what extent they explicitly or implicitly may provide arguments to establish a delimitation between air space and outer space. Not surprisingly, the laws reviewed by von der Dunk did not provide any clues that might provide evidence of an intent to establish such a demarcation. However, six years later a law was enacted in the United States that could potentially pass the test enunciated by von der Dunk and perhaps have an impact on the debate of the delineation of outer space.

The Commercial Space Launch Amendments Act of 2004 establishes a regulatory regime tailored to the needs and dangers of the commercial space launch business, which intends to free the industry from the tangle of ill-suited regulations with which it has been forced to contend, and consequently allowing the private sector to challenge the hegemony of NASA in space.7 Notably, the law classifies the vehicles to be used for commercial space tourism as “launch vehicles” and “reentry vehicles.” The act does not refer to the vehicles as aircraft.

It is uncertain even if commercial space activities, coupled with US national space law such as the Commercial Space Launch Amendments Act of 2004, will be sufficient to establish an internationally recognized customary norm.

Arguably, this classification and the definition of “spaceflight participant” within in the act could be construed from the functionalist standpoint to represent that these vehicles, most of which will be suborbital in nature, and their passengers will transit within 100 to 112 kilometers, which from a spatial point of view is considered within the area of the lower limits of “outer space”. However, even though the functional altitude of these vehicles will be within the boundary of “air space” and “outer space”, there is no indication that the act in of itself intends to make a demarcation either functionally or spatially.

While there is a weak argument that the recognition of these vehicles as spacecraft and their passengers as “spaceflight participants” could be used as an element to build a case that both will performing their activities within a region often recognized within an internationally acceptable delimitation, in of itself the act would not provide a solid basis for making that argument. Nevertheless, despite this shortcoming, the act itself, coupled with the actual practice of suborbital flights, might provide a basis to infer a customary norm from a combination of both spatial and functional viewpoints.

Customary law and commercial space activities

There is little argument that commercial space activities will provide a challenge to the current body of international space law, and there are differing opinions internationally regarding the regulation of those activities. There is also a viewpoint that some of these challenges will be met by customary law instead of formal treaties. Ironically, while commercial space challenges international space law in one sense, it may unintentionally provide through customary law a means to help settle the debate of the delimitation between air space and the lower limits of outer space.

More to the point, the question may arise of whether commercial spaceflights performed by vehicles functionally designated as spacecraft, which operate within the spatial area commonly recognized as inside the area of the upper limit of air space and the lower limit of outer space, represent a practice that can be used to form an international customary recognition of the delimitation of outer space? The question is a touchy one considering that the United States, through promoting commercial space activities, could also find itself inadvertently providing support for an issue that itself has touted publically as an unimportant one.

However, it is uncertain even if commercial space activities, coupled with US national space law such as the Commercial Space Launch Amendments Act of 2004, will be sufficient to establish an internationally recognized customary norm. Even if it does, the expressed opinion of China and Russia that the issue should be addressed via a legally-binding treaty makes it unclear whether these two nations, who are major space powers in their own right, would be willing to accept a customary norm as the do-all and end-all to the issue. However, like the stance that both nations have taken in regards to the use of transparency and confidence building measures (TCBMs) to address outer space security, it is plausible that either or both countries would look upon such a customary norm regarding the delimitation of outer space as an acceptable stepping stone, with the caveat that it lead to a legally-binding accord.


While a scenario could play out where the debate is reignited and commercial space is used to bolster a hard and fast rule, it is equally plausible that commercial space activities, including suborbital flights, could progress without mention of the topic. The only certainty is that until it is resolved to the satisfaction of the international community, the issue will be one of the many that looks for resolution in the sphere of international space law.


1 National Security Council Planning Board. NSC 5814/1. “Preliminary U.S. Policy on Outer Space.” Dwight D. Eisenhower Presidential Library and Museum. 20 Jun. 1958.

2 See Delbert R. Terrill, Jr., The Air Force Role of Developing International Outer Space Law, Air Force University Press, p. 30.

3 Frans vonder Dunk, THE DELIMITATION OF OUTER SPACE REVISITED The Role of National Space Laws in the Delimitation Issue, Space and Telecommunications Law Program Faculty Publications, p. 257, January 1, 1998.

4 US Statement, Definition and Delimitation of Outer Space And The Character And Utilization Of The Geostationary Orbit, Legal Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space at its 40th Session in Vienna from April, STATEMENT BY THE DELEGATION OF THE UNITED STATES OF AMERICA, April 2001.

5 The agreement desired by the Russian Federation would also allow a space object of any State to pass over the territory of other States at lower altitudes for the purpose of reaching orbit or returning to Earth.

6 von der Dunk, p. 255.

7 Commercial Space Launch Amendments Act of 2004, Harvard Journal of Law & Technology, Volume 17, Number 2 Spring 2004, p. 619.