well as for guidance and propulsion in addition the power supply could also comprise a plurality of wind vanes 68 the wind vanes may be arranged to face in different directions so that at least some of them are always facing the prevailing winds the wind vanes 68 can be used to generate electric power in a well known manner which also can be used by the telecommunication equipment as well as for guidance and propulsion as seen in fig4 an alternate power supply 66 may be provided in the form of a microwave energy system of similar to that which has been developed by endosat inc of rockville md the microwave energy system includes a ground based microwave generator not shown that creates a microwave energy beam of about 35 ghz this beam is directed to receptors 80 on the relay 28 and there converted to direct current in a manner similar to the solar energy system the microwave energy system could supply power sufficient to operate the telecommunications system on the relay station as well as provide power for guidance and propulsion further the relay stations 28 may be provided with at least one microwave transmitter and suitable means for aiming the microwave transmitter at a microwave receiving means on another relay station 28 so that a source other than the ground based microwave generator is available to provide microwave energy to the relay stations as seen in fig3 and 4 the navigation thrust.