Author : Soubhratra Bhattacharjee

College: Jogesh Chandra Chaudhuri Law College, University of Calcutta

Year of Study: 3rd Year


Nuclear Power Sources (NPS) are now used widely in various space missions by space agencies. The main objective behind the use of Nuclear power sources (hereinafter, NPS) in space is to utilize their compactness and long life and also to use the more power generating capacity by onboard solar panels or any other means. Various space missions like missions to Mars and Pluto carry nuclear power sources. Various space agencies like NASA, SpaceX have also confirmed the use of NPS in space as a part of their future missions. In this article, the principles relating to the use of such NPS is going to be discussed.


Space, Nuclear, Power, Principles, United Nations.


The United Nations General Assembly in 1978 endorsed the recommendations for Scientific and Technical Subcommittee on the committee of the Peaceful Uses of Outer Space to formally consider the technical aspects and the safety measures relating to the use of Nuclear Power Sources in the Outer Space, keeping in mind of its hazardous nature. These recommendations led to the adoption of the principles by the General Assembly in 1992. Under these principles, the member states are required to inform the Secretary-General regarding safety assessments required to be carried out before launching of the nuclear powered space objects for dissemination to other States and the general public.

Apart from the NPS principles, the Safety Framework for Nuclear Power Source Applications in Outer Space was formed in 2009 for the purpose of promoting the safe use of NPS in outer space and that it can be used as a guide for national purposes. The Safety Principles are not bound by the International Law.

Principles Relating to the Use of NPS in Outer Space:-

The General Assembly having heard the report of the committee on the Peaceful Uses of Outer Space has recognized the use of Nuclear Power Sources in Outer Space as presented by the Committee. The General Assembly further mentions that:-

  •  For some missions in outer space nuclear power sources are extremely suited and essential owing to their compactness, attributes and long life
  • The use of nuclear power sources should focus on those applications which take advantage of the particular properties of the nuclear power sources
  • The Assembly further recognizes that the use of nuclear power sources should be based on a thorough safety assessment, including probable risk analysis, with reducing the risk of accidental exposure of harmful radiation to the public
  • The Assembly also states that the need for such a set of principles containing guidelines is only to ensure the safe use of Nuclear power sources in outer space.
  • These Principles are only to be applied in nuclear power sources in outer space devoted to the generation of electric power onboard space objects for non- propulsive purposes.
  • These principles are subject to modification and revision in view of emerging nuclear power applications and on evolving international recommendations on radiological protection.

The following are the principles as mentioned in report by the UN General Assembly: –

Principle 1- Applicability of International Law:-

The first principle regarding the use of NPS states that all the activities involving the use of Nuclear Power Sources shall be in conformation with the international law including in particular the Charter of United Nations.

Principle 2- Use of Terms:-

According to the Principles, the term ‘Launching States’ and ‘State Launching’ means the State which exercises jurisdiction and control over a space object with nuclear power sources on board at a given point in time. The Principle also defines the terms ‘foreseeable’ and ‘all possible’ as a class of events or circumstances whose overall possibility is such that it is considered to encompass only credible possibilities for the purposes of safety analysis.

Principle 3- Guidelines and Criteria for Safe Use:-

The following are the guidelines for the safe use of Nuclear power sources: –

  • States launching space objects for Nuclear power sources on board shall protect individuals, population and the biosphere against radiological hazards.
  • During normal operations of space objects with nuclear power sources on board shall ensure with confidence that the hazards in foreseeable operational or accidental circumstances are kept below certain acceptable levels.
  • The design and structure of Nuclear power source systems shall be made in such a way so that they are in accordance with internationally accepted radiological protection guidelines to limit the exposure to accidents.
  • The systems important for safety shall be designed, constructed and operated in accordance to the concept of defense in depth.
  • The principle also mentions that radioisotope generators shall be used for interplanetary missions and other missions leaving the field of gravity of Earth.
  • Radioisotope generators shall be protected by a containment system that is designed and constructed to withstand the heat and aerodynamic forces for re-entry in the upper atmosphere of the Earth.

Principle 4- Safety Assessment:-

This principle mentions that a launching state at the time of launch shall, prior to the launch, go through corporative arrangements where the design, structure or the manufacture of the Nuclear space objects would be assessed. This assessment shall also cover all the relevant phases of the mission and shall deal with the system involved including the means of launching, the space platform and such other necessary things.

The results of the safety assessments together with the extent feasible, and an indication of the approximate intended time frame of the launch, shall be made publicly available prior to each launch and the Secretary General of the United Nations shall be informed on how States may obtain such results of safety assessments prior to each launch.

Principle 5- Notification of Re-Entry:-

The principle mentions that any State launching a space object with nuclear power sources on board shall in a suitable time period inform other States involved in this space object program about the malfunctioning with the risk of re entry of harmful radioactive materials to the Earth.

The principle also mentions that the information shall be provided by the launching State as soon as it becomes aware of the malfunction and any such updated information shall be transmitted to the Secretary-General of the United Nations.

Principle 6- Consultations:-

This principle states that all the States which are providing information to other States about any malfunction or such other problems may also from time to time, respond promptly to any other information or consultations sought by such other States.

Principle 7- Assistance to States:-

The main objective behind this principle is international cooperation and unity. It states that on the notification of an expected re-entry of radioactive material or its components into the Earth’s atmosphere, all States possessing space monitoring and tracking facilities shall communicate the relevant information that may be available on the malfunctioning space object to the Secretary-general of the United Nations and the State concerned as quickly as possible, so that the affected State can take precautionary measures.

Principle 8- Responsibility:-

This principle mentions that it will be the sole responsibility of the State for any mishap or other such situations as may arise or likely to arise while conducting national activities involving nuclear power sources in outer space whether such activities are carried out by governmental agencies or private agencies and that these activities are carried in conformity with the principles laid down in the report of the General Assembly.

Principle 9- Liability and Compensation:-

The principle herein states that any State which launches or procures the launching of a space object and each state from whose territory or facility a space object is launched shall be internationally liable for the damage caused by such space object or its components.

The principle also mentions that the States will be liable for any damage as per the United Nations Office for Outer Space Affairs which shall be determined in accordance with international law, in order to provide such reparation for any damage caused which shall restore the person, State or international organization on whose behalf a claim is presented.

Principle 10- Settlement of Disputes:-

All the disputes resulting from the application of these principles shall be resolved through negotiations or any other established procedures for the peaceful settlement of disputes in accordance with the charter of the United Nations.

Principle 11- Review and Revisions:-

The last principle in the report of the General Assembly mentions that such principles are to be reopened by the committee on the Peaceful Uses of Outer Space not later than two years after their adoption.

These are the principles relating to the use of Nuclear power sources in outer space in its report by the General Assembly.


Despite the adoption of the Nuclear Power Source principles, the issue of space NPS remains a topic of interest to the member states. After many discussions and preparations, the scientific and technical Subcommittee and the International Atomic Energy Agency agreed in 2007 to jointly draft a safety framework for NPS application in outer space. This partnership integrated the expertise of the Scientific and Technical Subcommittee in the use of space NPS with the established procedures of the IAEA for developing safety standards pertaining to nuclear safety of terrestrial applications.

In the modern times, space agencies are shifting towards the use of Nuclear power sources because it is considered less harmful. For example, the 2011-12 Mars mission, measured a very high radiation on its 36-week journey to Mars. According to scientists, two forms of radiation pose potential health risks one being Galactic Cosmic Rays, caused by supernova explosions and the other being solar energetic particles associated with solar flares and coronal mass ejections from the Sun. Thus, the only way to reduce the exposure of these radiations from the crew would be to use nuclear propulsions, reducing the transit time considerably. This is the sole reason why most of the space agencies are shifting towards the use of Nuclear power sources.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this:
search previous next tag category expand menu location phone mail time cart zoom edit close