Page images
PDF
EPUB

General have made their reports. The full Committee can then frame its report to the General Assembly covering all four topics. We hope that last phase can be finished by July 31.

Statement by the United States Representative (Meeker) Before the Legal Subcommittee of the Ad Hoc Committee on the Peaceful Uses of Outer Space, May 28, 1959 1

[Extracts]

The United States delegation has today [May 28] circulated a working paper in document AC.98/L.7 of the United Nations Ad Hoc Committee on the Peaceful Uses of Outer Space.

[ocr errors][merged small]

Our delegation has thought it would be most helpful to the General Assembly in its further consideration of international cooperation in the peaceful uses of outer space if the presently identifiable legal problems were to be sorted into two general groupings so as to mark separately those problems which seemed to call for and be amenable to relatively early treatment by the community of nations from those that did not. With this in mind we have listed the following six general topics as priority problems:

1. Availability of outer space for exploration and use;

2. Liability for injury or damage caused by space vehicles;

3. Allocation of radio frequencies;

4. Interference between spacecraft and aircraft;

5. Identification and registration of space vehicles and coordination of launchings;

6. Reentry and landing of space vehicles.

I want to say that all of these items refer to relationships among governments and are not immediately and primarily concerned with questions that might arise between governments and private persons.

In addition I would like to call attention to the recommendation in the draft report that the legal problems and their relative priority be kept under regular review by whatever means the General Assembly should deem appropriate. The problems mentioned in the second grouping of the draft report are:

1. The boundaries of air space and of outer space;

2. The feasibility and desirability of a comprehensive codification of rules of law applicable to activities in outer space; and 3. Problems relating to the exploration of celestial bodies. Finally, the draft report mentions the problems of physical interference among space vehicles and relations with any extraterrestrial forms of life that might one day be encountered abroad in the universe.

1 Department of State Bulletin, June 29, 1959, p, 974. Leonard Meeker was Assistant Legal Adviser for United Nations Affairs, Department of State, 1951-1961.

Report to the Geneva Conference on the Discontinuance of Nuclear-Weapon Tests by the Technical Working Group on the Detection and Identification of High-Altitude Nuclear Explosions, July 10, 1959 1

1

At the direction of the Conference on the Discontinuance of Nuclear Weapon Tests, the Technical Working Group has examined the possible techniques for the detection and identification of high-altitude nuclear explosions under the following terms of reference:

The Technical Working Group should assess the capabilities and limitations of possible techniques for the detection and identification of nuclear explosions at high altitudes (more than 30-50 kilometres) above the earth and, on the basis of the discussions and conclusions of the Geneva Conference of Experts, recommend techniques and instrumentation for consideration by the Conference for incorporation in the Detection and Identification System.

The Technical Working Group considered the detection of nuclear explosions in the region extending from 30-50 kilometres above the earth to hundreds of millions of kilometres from the earth.

Recognizing that the Geneva Conference of Experts in 1958 considered that it is possible to use the methods of recording gamma radiations and neutrons by instrumented earth satellites, pointing out the capabilities and limitations of the methods of recording gamma radiations, and also the methods of recording optical phenomena and ionospheric phenomena at ground stations for the detection of nuclear explosions at high altitudes, the Technical Working Group additionally considered and assessed the capabilities and limitations of these techniques. The Technical Working Group has also assessed the capabilities and limitations of new techniques of detection based on observing electrons trapped in the earth's magnetic field by instrumented earth satellites, soft thermal X-rays by instrumented earth and solar satellites, and backscatter radar signals from the ionosphere at ground stations.

As a result of further consideration of the detection and identification techniques mentioned in the conclusions of the Geneva Conference of Experts and of methods and techniques which are not mentioned in the conclusions of the Experts, the Technical Working Group has arrived at the following conclusions in regard to the capabilities and limitations of the possible techniques for the detection and identification of nuclear explosions at high altitude (more than 30-50 kilometres) above the earth.

A. Detection of High-Altitude Nuclear Explosions by Means of Apparatus Installed in Satellites

1. It is technically feasible by means of a multiple coincidence arrangement of suitable counters, for example, scintillation counters, to detect the prompt gamma rays from a one-kiloton nuclear explosion at an estimated distance of about 300,000 kilometres when the explosion is unshielded; the distance could be reduced by one order of magnitude when the explosion is shielded in a manner that would increase the total weight of the device by several times. The number of counters necessary for recording would be lower if the satellites were located outside the inner radiation belt of the earth and greater

1 Documents on Disarmament, 1945-1959, vol. II, pp. 1427-1434.

if the satellites were located within the inner radiation belt. The counters must be separated by a sufficient distance to avoid signals due to cosmic ray showers.

2. It is technically feasible by means of suitable counters, for example, scintillation counters, with appropriate geometry and capable of discriminating against the hard component of penetrating particles, to detect the delayed fission gamma rays from a one-kiloton nuclear explosion at an estimated distance of about 300,000 kilometres. When operated outside the inner radiation belt of the earth the system of counters would be simplified. This method is not sensitive to shielding of the nuclear explosion.

3. It is technically feasible by means of neutron counters, employing a moderator and not located within the inner radiation belt of the earth, to detect the prompt neutrons from a one-kiloton nuclear explosion at an estimated distance of up to 100,000 kilometres when unshielded and at shorter distances when shielded. The weight of shielding would be smaller than in the case of gamma radiation for a comparable reduction in detection distance. At distances of the order of 10,000 kilometres, it is possible to detect such an explosion by means of delayed neutrons. This method of detecting delayed neutrons is not sensitive to shielding of the nuclear explosion.

4. It is technically feasible by means of an array of photomultipliers or a system of appropriate counters (for example, thin inorganic scintillation counters covered with thin foils) to detect soft thermal X-rays from an unshielded 10 kiloton nuclear explosion at an estimated distance of a few hundred million kilometres when the detector is not located within the earth's radiation belt. When the X-ray detector is located within the earth's radiation belt, the estimated detection distance is reduced by an order of magnitude. When the explosion is shielded by means of a reflector having large dimensions and a weight which is comparable to the weight of the device, the estimated detection distances of high yield nuclear explosions (in the megaton range) can be reduced by one or two orders of magnitude and by an even greater amount for low yield nuclear explosions (in the kiloton range). Lighter shields will accomplish the same reduction in detection capability against detectors covered by foils.

5. It is technically feasible by means of simple electron counters to detect the electrons trapped in the earth's magnetic field and resulting from a one-kiloton nuclear explosion occurring between approximately 70° N. and 70° S. magnetic latitude and at altitudes of from 100-700 kilometres, depending on the longitude, up to an altitude of 20,000 kilometres. Outside this special region the capabilities of this method decrease very rapidly.

6. A group of 5-6 earth satellites, maintained in appropriate orbits at altitudes of several tens of thousands of kilometres, allows for complete earth surveillance and, given the presence of instrumentation listed in paragraphs 1-4 of this Section, is capable of detecting nuclear explosions at altitudes above the altitude at which radiation could escape from the atmosphere (i.e., 30 kilometres for gamma rays and neutrons and 75-100 kilometres for soft thermal X-rays) and also nuclear explosions in cosmic space up to distances in accordance with the recording capabilities of detectors of radiation listed in paragraphs 1-4 of this Section. If complete earth surveillance were car

ried out by satellites operating at lower altitude, a large number of satellites would be required, depending on the altitude. Such detection systems cannot detect nuclear explosions which might be carried out behind the moon or the sun away from the earth.

7. Since the difficulty of establishing a satellite in orbit around the earth increases with altitude and since the difficulty of establishing a system of satellites at a given altitude increases as the number of satellites becomes greater, the Technical Working Group notes that it is technically feasible to detect high altitude nuclear explosions by means of techniques specified in paragraphs 1-4 of this Section with various systems of earth satellites. It is possible to detect explosions over the entire surface of the earth by using satellites with lower orbits and correspondingly increasing the number of satellites. A system of satellites ensuring full surveillance of the earth will at the same time ensure the surveillance of a considerable part of the earth by more than one satellite at a time. Such detection systems cannot detect nuclear explosions which might be carried out behind the moon or the sun away from the earth. If the use of satellites is to be limited to detecting explosions carried out above certain altitudes over the earth, the number of satellites may be correspondingly reduced. For example, while 50-70 satellites at 700 kilometres and 10-20 satellites at 2,000 kilometres are needed for complete earth surveillance, a system of 8-10 satellites will detect nuclear explosions except in limited predictable areas near the earth extending to altitudes of about 550-2,000 kilometres for the 700 kilometre orbits and to altitudes of about 120-750 kilometres for the 2,000 kilometre orbits.

The number of satellites required depends upon the accuracy of their position in the orbits.

8. A single satellite equipped with simple electron counters, and in an appropriate orbit which intercepts the region in which electrons may be trapped in the earth's magnetic field, could detect the trapped electrons from nuclear explosions occurring in the region indicated in paragraph 5 of this Section.

9. The systems of earth satellites described in paragraphs 6 and 7 above cannot detect nuclear explosions carried out in certain regions of controlled space, namely, behind the moon or the sun away from the earth. Unshielded nuclear explosions in these regions can, however, be detected by the apparatus for X-ray detection, assessed in paragraph 4 above, when installed in a system of four satellites circling the sun in appropriate orbits, provided data from these satellites is regularly received on the earth. Bearing in mind that shielded nuclear devices will have to be stabilized in all cases, the Technical Working Group notes that for nuclear explosions at great distances from the earth, heavier shields would be required to reduce the capabilities of such a system of solar satellites than would be required to reduce the detection capabilities of the earth satellite system. B. Detection of High Altitude Nuclear Explosions by Means of Apparatus Installed at Control Posts

1. It is technically feasible by means of a system of optical detectors, mounted behind telescopic lenses, to detect the visible light from a one-kiloton nuclear explosion at estimated distances of about 100,000 kilometres during the day and about 300,000 kilometres during the night. These ranges will be three times greater for megaton explo

sions. The minimum altitude for complete surveillance is determined by both the control post spacing and the angular aperture of the detector. For the 1,700 kilometre spacing of control posts the minimum altitude for complete surveillance is about 1,000 kilometres for a 60° aperture and about 2,500 kilometres for a 30° aperture. Larger apertures would allow a reduction of the minimum altitude for complete surveillance depending on atmospheric conditions. The performance of this detection method is not substantially affected by shields. Cloud cover over a control post will nullify the effectiveness of the detector at that post. However, simultaneous cloud cover for all line-of-sight posts is unlikely for a nuclear explosion at very high altitude.

2. It is technically feasible by means of an optical detector and a narrow band filter, mounted behind a wide angle lens, to detect the visible fluorescence created in the upper atmosphere by thermal radiation from a 10-kiloton nuclear explosion at an estimated distance of several hundred thousand kilometres from the earth. Detection at somewhat larger distances is possible at night. For the 1,700 kilometre spacing of control posts, the minimum altitude for complete surveillance above the earth is about 400 kilometres. For heavy cloud cover the range detection is reduced by a factor of ten.

3. It is technically feasible, by means of a network of 25 to 50 backscatter radar installations operating at frequencies of 10-30 megacycles, to detect the appearance of additional ionization at the source of the explosion and of additional ionization in the atmosphere produced by high-altitude nuclear explosions with a yield above one kiloton at altitudes from 30-50 kilometres and extending to several thousand kilometres. The location of the explosion and the region of additional ionization might be separated by considerable distances. Additional ionization in the atmosphere at the two magnetic conjugate points of the earth arises from nuclear explosions occurring in regions of space limited by 70° N. and 70° S. magnetic latitudes and by altitudes from 70-100 kilometres up to several thousand kilometres. Outside this region of latitudes increased ionization could occur only at the magnetic conjugate point nearer the explosion. The main difficulty with this method is the occurrence of natural phenomena giving similar signals. The use of this method is substantially more difficult in polar regions where aurorae occur. Simultaneous observations from several stations are desirable to help in discriminating nuclear explosions from the natural background. The use of this method might produce interference with instruments at control posts and would require measures to overcome this interference.

4. It is technically feasible by means of observation of absorption of cosmic radio noise in the ionosphere to detect the changes in the ionosphere produced by unshielded nuclear explosions of 10-20 kilotons occurring in the height range extending from 30-50 kilometres up to an altitude ranging from thousands to tens of thousands of kilometres, depending on the spectrum of thermal X-rays produced by the nuclear explosion and on the type of detection apparatus employed. The explosion and the disturbance of the ionosphere can occur at considerable distance from one another. The main difficulty with this method for identification purposes is the possibility of the occurrence of effects of a similar type in the sunlit ionosphere during so-called "sudden ionospheric disturbances", during auroral disturb

« PreviousContinue »