0191 -9067/81 /040337-10$02.00/0 Copyright ® 1981 SUNSAT Energy Council ANALYSIS OF GEOSTATIONARY ORBITAL SLOT AVAILABILITY FOR THE SPS PROGRAMME RICHARD J. FLOWER British Aerospace Dynamics Group Bristol. England Abstract—Analyses were carried out. using predicted future geostationary satellite numbers and distributions, to examine geostationary orbital slot availability on a global and domestic basis. The various international considerations applicable to the geostationary orbit are discussed, with particular attention being paid to potential conflict areas. The factors involved in the definition of geostationary satellite spacing conditions are described, and their effects analysed with respect to SPS. Three separate distribution characteristics are considered to estimate geostationary satellite numbers and distributions in 1991. From these distributions, predictions are made of orbital slot availability as a function of satellite spacing on a global basis, and also when applied specifically to the U.S.A, and W. Europe. In the European case, attempts are made to compare regional consumption area power density demands with potential orbital slot availability for the SPS. INTRODUCTION The first successful geostationary communications satellite was SYNCOM 2 in 1963. Since then, numbers have increased rapidly with the global INTELSAT series, various domestic and international systems, and military and scientific satellites. The present total of active GEOSATs is estimated by the author as 73, with a predicted 273 further launches before 1991. It is thought that there will be 239 active satellites in geostationary orbit by the end of 1990 (1). Already the geostationary orbit has proved so popular that orbital overcrowding has become a potential problem. It is not so much that the satellites may collide with each other — although this does have to be considered — as it is a problem of electromagnetic interference. This problem will have to be very carefully analysed with respect to the massive projected demand of the SPS programme upon the geostationary orbit. INTERNATIONAL AND LEGAL ISSUES A number of existing international organisations, both scientific and political, are involved in the governing of space objects at geostationary heights. The public international institutions include the UN (and in particular COPUOUS), and the ITU. With respect to SPS, there are several issues in need of clarification before the
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