Outer Space Treaty

File:Signing Outer Space Treaty.jpg

Signing of the Outer Space Treaty

The Outer Space Treaty, formally called the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a multilateral treaty that forms the basis of international space law.

Negotiated and drafted under the auspices of the United Nations, it was opened for signature in the United States, the United Kingdom, and the Soviet Union on 27 January 1967, entering into force on 10 October 1967. As of May 2025, 117 countries are parties to the treaty—including all major spacefaring nations—and another 22 are signatories.

Key provisions of the treaty include prohibiting nuclear weapons in space; limiting the use of the Moon and all other celestial bodies to peaceful purposes; establishing that space shall be freely explored and used by all nations; and precluding any country from claiming sovereignty over outer space or any celestial body. Although it forbids establishing military bases, testing weapons and conducting military maneuvers on celestial bodies, the treaty does not expressly ban all military activities in space, nor the establishment of military space forces or the placement of conventional weapons in space.

The OST also declares that space is an area for free use and exploration by all and "shall be the province of all mankind". Drawing heavily from the Antarctic Treaty of 1961, the Outer Space Treaty likewise focuses on regulating certain activities and preventing unrestricted competition that were thought might lead to conflict at that time. Consequently, it is largely silent or ambiguous on newly developed space activities such as lunar and asteroid mining.

OST was at the heart of a 'network' of inter-state treaties and strategic power negotiations to achieve the best available conditions for nuclear weapons world security.

OST was the most important link in the chain of international legal arrangements for space from the late 1950s to the mid-1980s. The OST was followed by four additional agreements, with varied levels of accession: the safe return of astronauts who land in a foreign country (1967); liability for damages caused by spacecraft (1972); the registration of space vehicles (1976); and rules for activities on the Moon (1979). As the first and most foundational legal instrument of space law, the Outer Space Treaty and its broader principles of promoting the civil and peaceful use of space continue to underpin multilateral initiatives in space, such as the International Space Station and the Artemis Program.

History

The Outer Space Treaty was spurred by the development of intercontinental ballistic missiles (ICBMs) in the 1950s, which could reach targets through outer space. The Soviet Union's launch of Sputnik, the first artificial satellite, in October 1957, followed by a subsequent arms race with the United States, hastened proposals to prohibit the use of outer space for military purposes. On 17 October 1963, the U.N. General Assembly unanimously adopted a resolution prohibiting the introduction of weapons of mass destruction in outer space. Various proposals for an arms control treaty governing outer space were debated during a General Assembly session in December 1966, culminating in the drafting and adoption of the Outer Space Treaty the following January.

Provisions

The Outer Space Treaty represents the basic legal framework of international space law. According to the U.N. Office for Outer Space Affairs (UNOOSA), the core principles of the treaty are:

• the exploration and use of outer space shall be carried out for the benefit and in the interests of all countries and shall be the province of all mankind;
• outer space shall be free for exploration and use by all states;
• outer space is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means;
• states shall not place nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies or station them in outer space in any other manner;
• the Moon and other celestial bodies shall be used exclusively for peaceful purposes; prohibits their use for testing weapons of any kind, conducting military maneuvers, or establishing military bases, installations, and fortifications
• astronauts shall be regarded as the envoys of mankind;
• states shall be responsible for national space activities whether carried out by governmental or non-governmental entities;
• states shall be liable for damage caused by their space objects; and
• states shall avoid harmful contamination of space and celestial bodies.

Among its principles, it bars states party to the treaty from placing weapons of mass destruction in Earth orbit, installing them on the Moon or any other celestial body, or otherwise stationing them in outer space. It specifically limits the use of the Moon and other celestial bodies to peaceful purposes, and expressly prohibits their use for testing weapons of any kind, conducting military maneuvers, or establishing military bases, installations, and fortifications (Article IV). However, the treaty does not prohibit the placement of conventional weapons in orbit, and thus some highly destructive attack tactics, such as kinetic bombardment, are still potentially allowable. In addition, the treaty explicitly allows the use of military personnel and resources to support peaceful uses of space, mirroring a common practice permitted by the Antarctic Treaty regarding that continent. The treaty also states that the exploration of outer space shall be done to benefit all countries and that space shall be free for exploration and use by all the states.

Article II of the treaty explicitly forbids any government from "appropriating" a celestial body such as the Moon or a planet, whether by declaration, use, occupation, or "any other means". However, the state that launches a space object, such as a satellite or space station, retains jurisdiction and control over that object; by extension, a state is also liable for damages caused by its space object.

Responsibility for activities in space

Article VI of the Outer Space Treaty deals with international responsibility, stating that "the activities of non-governmental entities in outer space, including the Moon and other celestial bodies, shall require authorization and continuing supervision by the appropriate State Party to the Treaty" and that States Party shall bear international responsibility for national space activities whether carried out by governmental or non-governmental entities.

As a result of discussions arising from Project West Ford in 1963, a consultation clause was included in Article IX of the Outer Space Treaty: "A State Party to the Treaty which has reason to believe that an activity or experiment planned by another State Party in outer space, including the Moon and other celestial bodies, would cause potentially harmful interference with activities in the peaceful exploration and use of outer space, including the Moon and other celestial bodies, may request consultation concerning the activity or experiment."

Applicability in the 21st century

Being primarily an arms control treaty for the peaceful use of outer space, the Outer Space Treaty offers limited and ambiguous regulations to newer space activities such as lunar and asteroid mining. It is therefore debated whether the extraction of resources falls within the prohibitive language of appropriation, or whether the use of such resources encompasses the commercial use and exploitation.

Seeking clearer guidelines, private U.S. companies lobbied the U.S. government, which in 2015 introduced the U.S. Commercial Space Launch Competitiveness Act of 2015 legalizing space mining. Similar national legislation to legalize the appropriation of extraterrestrial resources are now being introduced by other countries, including Luxembourg, Japan, China, India, and Russia. In addition, the U.S. has led the creation of a series of bilateral agreements known as the Artemis Accords that seek to clarify a number of issues related to the Outer Space Treaty, including the use of space resources. This has created some controversy regarding legal claims over the mining of celestial bodies for profit.

1976 Bogota Declaration

The "Declaration of the First Meeting of Equatorial Countries", also known as the "Bogota Declaration", was one of the few attempts to challenge the Outer Space Treaty. It was promulgated in 1976 by eight equatorial countries to assert sovereignty over those portions of the geostationary orbit that continuously lie over the signatory nations' territory. These claims did not receive wider international support or recognition, and were subsequently abandoned.

Influence on space law

As the first international legal instrument concerning space, the Outer Space Treaty is considered the "cornerstone" of space law. It was also the first major achievement of the United Nations in this area of law, following the adoption of the first U.N. General Assembly resolution on space in 1958, and the first meeting of the U.N. Committee on the Peaceful Uses of Outer Space (COPUOS) the subsequent year.

Within roughly a decade of the treaty's entry into force, several other treaties were brokered by the U.N. to further develop the legal framework for activities in space:

• Rescue Agreement (1968)
• Space Liability Convention (1972)
• Registration Convention (1976)
• Moon Treaty (1979)

With the exception of the Moon Treaty, to which only 18 nations are party, all other treaties on space law have been ratified by most major space-faring nations (namely those capable of orbital spaceflight). COPUOS coordinates these treaties and other questions of space jurisdiction, aided by the U.N. Office for Outer Space Affairs.

List of parties

The Outer Space Treaty was opened for signature in the United States, the United Kingdom, and the Soviet Union on 27 January 1967, and entered into force on 10 October 1967. As of May 2025, 117 countries are parties to the treaty, while another 22 have signed the treaty but have not completed ratification.

Multiple dates indicate the different days in which states submitted their signature or deposition, which varied by location: (L) for London, (M) for Moscow, and (W) for Washington, D.C. Also indicated is whether the state became a party by way of signature and subsequent ratification, by accession to the treaty after it had closed for signature, or by succession of states after separation from some other party to the treaty.

State	Signed	Deposited	Method
Afghanistan	Template:Plainlist	Template:Plainlist	Ratification
Algeria		Template:Dts (W)	Accession
Antigua and Barbuda		Template:Plainlist	Succession from United Kingdom
Argentina	Template:Plainlist	Template:Dts (M, W)	Ratification
Armenia		Template:Dts (M)	Accession
Australia	Template:Dts (W)	Template:Dts (L, M, W)	Ratification
Austria	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Azerbaijan		Template:Dts (L)	Accession
Bahamas		Template:Plainlist	Succession from United Kingdom
Bahrain		Template:Dts (M)	Accession
Bangladesh		Template:Plainlist	Accession
Barbados		Template:Dts (W)	Accession
Belarus	Template:Dts (M)	Template:Dts (M)	Ratification
Belgium	Template:Plainlist	Template:Plainlist	Ratification
Benin		Template:Plainlist	Accession
Bosnia and Herzegovina		Template:Dts (L)	Accession
Brazil	Template:Plainlist	Template:Dts (L, M, W)	Ratification
Bulgaria	Template:Dts (L, M, W)	Template:Plainlist	Ratification
Burkina Faso	Template:Dts (W)	Template:Dts (W)	Ratification
Canada	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Chile	Template:Plainlist	Template:Dts (W)	Ratification
China		Template:Plainlist	Accession
Colombia	Template:Dts (W)	Template:Plainlist	Ratification
Croatia		Template:Dts (W)	Accession
Cuba		Template:Dts (M)	Accession
Cyprus	Template:Plainlist	Template:Plainlist	Ratification
Czech Republic		Template:Plainlist	Succession from Czechoslovakia
Denmark	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Dominican Republic	Template:Dts (W)	Template:Dts (W)	Ratification
Ecuador	Template:Plainlist	Template:Dts (W)	Ratification
Egypt	Template:Dts (M, W)	Template:Plainlist	Ratification
El Salvador	Template:Dts (W)	Template:Dts (W)	Ratification
Equatorial Guinea		Template:Dts (M)	Accession
Estonia		Template:Dts (M)	Accession
Fiji		Template:Plainlist	Succession from United Kingdom
Finland	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
France	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Germany	Template:Dts (L, M, W)	Template:Dts (L, W)	Ratification
Greece	Template:Dts (W)	Template:Dts (L)	Ratification
Guinea-Bissau		Template:Dts (M)	Accession
Hungary	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Iceland	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
India	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Indonesia	Template:Plainlist	Template:Dts (L)	Ratification
Iraq	Template:Plainlist	Template:Plainlist	Ratification
Ireland	Template:Dts (L, W)	Template:Plainlist	Ratification
Israel	Template:Dts (L, M, W)	Template:Plainlist	Ratification
Italy	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Jamaica	Template:Dts (L, M, W)	Template:Plainlist	Ratification
Japan	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Kazakhstan		Template:Dts (M)	Accession
Kenya		Template:Dts (L)	Accession
North Korea		Template:Dts (M)	Accession
South Korea	Template:Dts (W)	Template:Dts (W)	Ratification
Kuwait		Template:Plainlist	Accession
Laos	Template:Plainlist	Template:Plainlist	Ratification
Latvia		Template:Dts (W)	Accession
Lebanon	Template:Dts (L, M, W)	Template:Plainlist	Ratification
Libya		Template:Dts (W)	Accession
Lithuania		Template:Dts (W)	Accession
Luxembourg	Template:Plainlist	Template:Dts (L, M, W)	Ratification
Madagascar		Template:Dts (W)	Accession
Mali		Template:Dts (M)	Accession
Malta		Template:Dts (L)	Accession
Mauritius		Template:Plainlist	Succession from United Kingdom
Mexico	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Mongolia	Template:Dts (M)	Template:Dts (M)	Ratification
Morocco		Template:Plainlist	Accession
Myanmar	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Nepal	Template:Plainlist	Template:Plainlist	Ratification
Netherlands	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
New Zealand	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Nicaragua	Template:Plainlist	Template:Plainlist	Ratification
Niger	Template:Dts (W)	Template:Plainlist	Ratification
Nigeria		Template:Dts (L)	Accession
Norway	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Oman		Template:Dts (L)	Accession
Pakistan	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Panama	Template:Dts (W)	Template:Dts (W)	Ratification
Papua New Guinea		Template:Plainlist	Succession from Australia
Paraguay		Template:Dts (L)	Accession
Peru	Template:Dts (W)	Template:Plainlist	Ratification
Poland	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Portugal		Template:Dts (L)	Accession
Qatar		Template:Dts (W)	Accession
Romania	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Russia	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification as the Soviet Union
Saint Vincent and the Grenadines		Template:Dts (L)	Succession from United Kingdom
San Marino	Template:Plainlist	Template:Plainlist	Ratification
Saudi Arabia		Template:Dts (W)	Accession
Seychelles		Template:Dts (L)	Accession
Sierra Leone	Template:Plainlist	Template:Plainlist	Ratification
Singapore		Template:Dts (L, M, W)	Accession
Slovakia		Template:Plainlist	Succession from Czechoslovakia
Slovenia		Template:Dts (L)	Accession
South Africa	Template:Dts (W)	Template:Plainlist	Ratification
Spain		Template:Plainlist	Accession
Sri Lanka	Template:Dts (L)	Template:Dts (L, M, W)	Ratification
Sweden	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Switzerland	Template:Plainlist	Template:Dts (L, M, W)	Ratification
Syria		Template:Dts (M)	Accession
Thailand	Template:Dts (L, M, W)	Template:Plainlist	Ratification
Togo	Template:Dts (W)	Template:Dts (W)	Ratification
Tonga		Template:Plainlist	Succession from United Kingdom
Tunisia	Template:Plainlist	Template:Plainlist	Ratification
Turkey	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Uganda		Template:Dts (W)	Accession
Ukraine	Template:Dts (M)	Template:Dts (M)	Ratification
United Arab Emirates		Template:Dts (W)	Accession
United Kingdom	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
United States	Template:Dts (L, M, W)	Template:Dts (L, M, W)	Ratification
Uruguay	Template:Plainlist	Template:Dts (W)	Ratification
Uzbekistan		Template:Dts (M)	Accession
Venezuela	Template:Dts (W)	Template:Dts (W)	Ratification
Vietnam		Template:Dts (M)	Accession
Yemen		Template:Dts (M)	Accession
Zambia		Template:Plainlist	Accession

Partially recognized state abiding by treaty

The Republic of China (Taiwan), which is currently recognized by Template:Numrec, ratified the treaty prior to the United Nations General Assembly's vote to transfer China's seat to the People's Republic of China (PRC) in 1971. When the PRC subsequently ratified the treaty, they described the Republic of China's (ROC) ratification as "illegal". The ROC has committed itself to continue to adhere to the requirements of the treaty, and the United States has declared that it still considers the ROC to be "bound by its obligations".

State	Signed	Deposited	Method
Template:Flagcountry	Template:Dts	Template:Dts	Ratification

States that have signed but not ratified

21 states have signed but not ratified the treaty.

State	Signed
Bolivia	Template:Dts (W)
Botswana	Template:Dts (W)
Burundi	Template:Dts (W)
Cameroon	Template:Dts (W)
Central African Republic	Template:Dts (W)
Democratic Republic of the Congo	Template:Plainlist
Ethiopia	Template:Plainlist
Gambia	Template:Dts (L)
Ghana	Template:Plainlist
Guyana	Template:Dts (W)
Haiti	Template:Dts (W)
Holy See	Template:Dts (L)
Honduras	Template:Dts (W)
Iran	Template:Dts (L)
Jordan	Template:Dts (W)
Lesotho	Template:Dts (W)
Malaysia	Template:Plainlist
Philippines	Template:Plainlist
Rwanda	Template:Dts (W)
Somalia	Template:Dts (W)
Trinidad and Tobago	Template:Plainlist

List of non-parties

The remaining UN member states and United Nations General Assembly observer states which have neither ratified nor signed the Outer Space Treaty are:

• Albania
• Andorra
• Angola
• Belize
• Bhutan
• Brunei
• Cambodia
• Cape Verde
• Chad
• Comoros
• Republic of the Congo
• Costa Rica
• Djibouti
• Dominica
• Template:Country data East Timor
• Eritrea
• Eswatini
• Gabon
• Template:Country data Georgia
• Grenada
• Guatemala
• Guinea
• Ivory Coast
• Kiribati
• Kyrgyzstan
• Liberia
• Liechtenstein
• Malawi
• Maldives
• Marshall Islands
• Mauritania
• Federated States of Micronesia
• Moldova
• Monaco
• Montenegro
• Mozambique
• Namibia
• Nauru
• Template:Country data North Macedonia
• Palau
• Palestine
• Saint Kitts and Nevis
• Saint Lucia
• Samoa
• São Tomé and Príncipe
• Senegal
• Serbia
• Solomon Islands
• South Sudan
• Sudan
• Suriname
• Tajikistan
• Tanzania
• Turkmenistan
• Tuvalu
• Vanuatu
• Zimbabwe

See also

• Common heritage of mankind
• Extraterritorial jurisdiction
• Extraterritorial operation
• Extraterritoriality
• High-altitude nuclear explosion (HANE)
• Human presence in space
• International waters
• International zone
• Kármán line
• Lunar Flag Assembly
• Militarization of space
• Moon Treaty
• SPACE Act of 2015
• Treaty on Open Skies
• United Nations Convention on the Law of the Sea

Further reading

• Annette Froehlich, et al. (2018). A Fresh View on the Outer Space Treaty. Vienna: Springer. Template:ISBN.
• Squadron Leader KK Nair's Space: The Frontiers of Modern Defence. Knowledge World Publishers, New Delhi, Chap. 5 "Examining Space Law...", pp. 84–104, available at Google Books.

External links

• Downloadable PDF 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"

• International Institute of Space Law
• Full text 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" in Arabic, Chinese, English, French, Russian, or Spanish
• Status of International Agreements relating to Activities in Outer Space (list of state parties to treaty), UN Office for Outer Space Affairs
• "The Case for Withdrawing from the 1967 Outer Space Treaty"
• Still Relevant (and Important) After All These Years: The case for supporting the Outer Space Treaty
• Introductory note by Vladimír Kopal, procedural history note and audiovisual material on the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies in the Historic Archives of the United Nations Audiovisual Library of International Law
• The Progressive Development of International Space Law by the United Nations—Lecture by Vladimír Kopal] in the Lecture Series of the United Nations Audiovisual Library of International Law
• The Law of Outer Space in the General Legal Field (Commonalities and Particularities)—Lecture by Vladlen Stepanovich Vereshchetin in the Lecture Series of the United Nations Audiovisual Library of International Law
• Humans on Mars and beyond full-text