The advantages of attitude stabilization and station keeping in communications satellite orbits

The power demands for broadband transmission of multichannel telephony are far greater than those for telemetry. Satellite communications repeaters might require inputs of the order of hundreds of watts and the weight and cost of solar cells to provide this power is considerable. Attitude stabilization is one method of economy in that it makes possible the utilization of satellite transmitting aerials of high gain. On the other hand, provision of stabilization equipment involves a payload weight penalty which might otherwise be allocated to additional power generators. There exists, for given aerial gain, a satellite mass for which the radiation flux at a given distance is the same whether the satellite is stabilized or not. The paper examines the dependence of this ¿critical mass¿ on aerial gain and satellite lifetime and shows that there is an optimum vehicle size for which stabilization pays the greatest dividend. The advantages and limitations of spin stabilization as a means of attitude control are discussed and the paper concludes with a comparison of random and station keeping (velocity controlled) satellites, the latter being possible where attitude stabilization is employed.