Although the United Nations has debated the issue for 40 years, there is no agreed legal definition of the term 'Outer Space' used in the international treaties relating to operations in the volume (somewhere) above the sovereign airspace of member states. One might well ask how laws can be framed on an undefined subject.

Space scientists call the space in which Earth satellites orbit the near-space environment, reserving the term outer space for the interplanetary medium, whereas astronomers reserve the term outer or deep space for the intergalactic medium.

The atmosphere slowly decreases in density with height and so does not offer a guideline as to where space starts. However, air drag does not allow a vehicle to remain in orbit very long once it descends to below about 200 kilometres.

The United States of America awards astronaut status to anyone who has flown above 80 km in altitude.

Astronautical flight engineers define an "entry interface" at around 120 km as the height at which significant heating occurs to a re-entering spacecraft. Natural space objects (meteoroids) also start to ablate or burn up at around this altitude, creating the visible meteors we see in the night sky.

The World Air Sports Federation sets 100 km as the lower boundary of space, and this altitude has been used in recent prizes set in competitions for flying into space. Many groups have adopted this 'Karman Line', named after the aeronautical engineer Theodore Von Karman who predicted the height below which significant lateral thrust would be required to keep a craft flying level.

White Knight carries Space Ship One in a private attempt to reach into space, defined in this case at an altitude of 100 km. (photo courtesy of Scaled Composites)

Although many states refuse to legally put an upper limit to their airspace, most do not control their air traffic above 60,000 ft (referred to as Flight Level 600), or about 18 km.

Some states believe that the entire space "above" their country should belong to them. This makes absolutely no sense whatever, and shows a distinct lack of understanding of Earth's place in the Universe. It is in fact based upon the geocentric cosmology that was espoused until its overthrow by Copernicus. If this principle were to apply, some states might lay claim to a star that is 'directly above' their territory at one point in time, only to find that an hour later the same star 'belonged' to a neighbouring state, and so on. Some equatorial states use this reasoning to lay exclusive claim to a portion of the much prized geosynchronous orbit, and feel that they should derive revenue from allocation of 'slots' in this orbit to others. Fortunately they are not in a position to enforce these claims. Neither has the absence of a legal delineation of outer space led to any international lawsuits to this end, for it is virtually certain that even with a reluctance to put a lower limit to the term, only a small minority of states would place it above geosynchronous orbit, at an altitude of 36,000 km.

In pragmatic terms, the height at which sovereign airspace above a state becomes outer space is only the height to which:

1. the state can defend the airspace below, and/or
2. other states allow it to so claim.

1. State Law
   (eg the issuance of permits for rocket launches)
2. Bilateral Treaties
   (eg establishing a tracking station in another country)
3. Multilateral Treaties
   (eg the establishment of the European Space Agency)
4. International Law
   (eg treaties made at and by the United Nations)

"Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies."

Short title: The Outer Space Treaty

Freedom of space for all. Not subject to national appropriation. International law applies. No military bases. No weapons of mass destruction. Astronauts as envoys - to be rendered assistance. States bear responsibility, ownership and liability for activities carried out under their jurisdiction. Peace, cooperation and mutual assistance. Opportunities for all. Inspections. Notifications of activities to UN.

This treaty contains elements of the following four treaties, which then reiterate and expand upon individual points declared here.

1968 ARRA

"Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space."

Short title: The Rescue and Return Agreement

Astronauts in distress to be given all possible assistance. Astronauts and space objects landing on foreign soil to be returned promptly to the launching state.

1972 LIAB

"Convention on International Liability for Damage Caused by Space Objects."

Short title: The Liability Treaty

States are responsible for any damage their space objects cause and must pay compensation to the damaged state.

1975 REG

"Convention on Registration of Objects Launched into Outer Space."

Short title: The Registration Treaty

All objects launched into space must be notified, by the launching state(s), to the UN Register of Space Objects.

1979 MOON

"Agreement Governing the Activities of States on the Moon and Other Celestial Bodies."

Short title: The Moon Treaty

Strengthens and expands the Outer Space Treaty (1967) for space bodies.

1. Declaration of Legal Principles Governing the Activities of States in the Exploration and Use of Outer Space

   Exploration and use of outer space should be for the benefit of all mankind. Outer space and any bodies in it are free for all and not subject to national appropriation. All activities should be peaceful. States bear international responsibility for national activities in space. States shall cooperate with each other in space. States retain control of their objects launched into space, and are liable for any damage such objects might cause. Astronauts shall be regarded as envoys of mankind. All possible assistance shall be rendered them in any emergency or accidental situation.

2. Principles Governing the Use by States of Artificial Satellites for International Direct Television Broadcasting

   Access to direct broadcast technology should be available to all states. States should respect the rights and sensitivities of other states (including copyright) in such broadcasts.

3. Principles Relating to Remote Sensing of the Earth from Outer Space

   Remote sensing activities to be carried out for the benefit of all states, and be used to protect the environment. Space capable states should make opportunities available to developing states for participation in this area. Data of any sense state should be made available to them.

4. Principles Relevant to the Use of Nuclear Power Sources in Outer Space

   In such operations individuals, populations and the biosphere should be protected against radiological hazards. There should be no significant contamination of outer space with radioactive material. Safety assessments shall be made available, and notifications made of nuclear powered vehicle re-entries into the Earth's atmosphere.

5. Declaration on International Cooperation in the Exploration and Use of Outer Space for the Benefit and in the Interest of All States, taking into Particular Account the Needs of Developing Countries.

   Encouragement of international cooperation in space operations with an onus on space capable states to assist and encourage developing states.

The full documentation on the UN treaties relating to outer space may be found at UN Treaties and Principles. An addendum covers the status of those treaties, with respect to which states have ratified them, as of January 2007.

However, it was not until 1998 that the Australian Commonwealth Government actually enacted specific space legislation which is termed the Australian Space Activities Act. This primarily relates to the regulation of space launches within Australia, and by Australians outside of Australia, and also the return of space objects to Australia. In essence, a space launch licence under this act makes the Australian Government liable under the UN Liability treaty for any damage caused by Australian space objects, and also allows Australia to claim the return of Australian space objects under the UN Rescue and Return treaty. Of course, this all comes at a considerable price to the applicant for such a licence.

Australian Space Activities Act 1998 Space Activities Amendment Bill 2002

Current US space policy has also been focused on regulating private space flight. This followed from the success of the Scaled Composites Space Ship One in a suborbital flight exceeding 100 km in altitude, and a subsequent proposal to make such flights available to paying passengers. The legislation recognises the inherent dangers in such operations and recognises that properly informed passengers should be given the right to undertake such ventures, whilst ensuring the safety of (uninvolved) people and property on the ground, and appropriate legal protection for the space operator, as long as compliance with the regulations is established and maintained.

USA National Space Policy 2006 Private Human Space Flight Regulations 2006

The European Centre for Space Law hosts a summer school on space law and policy each year at a low cost which includes accomodation and some meals. This two week course is held at various sites around Europe. ECSL Summer School

• OUTER SPACE: PROBLEMS OF LAW AND POLICY
  by Glenn H Reynolds [Westview Press 1998]
• INTERNATIONAL SPACE LAW
  by Boris Belitsky & A S Piradov [University Press of the Pacific 2000]
• SPACE POLICY IN THE TWENTY-FIRST CENTURY
  Edited by W Henry Lambright [John Hopkins University Press 2002]