In these five categories there are a lot of specific questions that must be answered to plan a working satellite communications system. A list of some of them follows. We haven’t attempted to cover everything, but these should give you some idea of the tasks and questions involved in planning an immense project like this. General Problems of a Satellite Communications System _What jobs could a communications satellite do best?_ _Should it be used for television?_ _Should it carry telephone messages? How many?_ _Would it be more valuable for data transmission? Facsimile?_ _What parts of the world should be covered?_ _Can all the problems of international cooperation be solved?_ _Would a satellite that could broadcast directly to home receivers be possible?_ _What military uses could a communications satellite system serve?_ _Would a passive satellite—one that reflects signals without amplifying them—be worth developing?_ _Or should the emphasis be on active repeaters, which can receive, amplify, and retransmit signals?_ _What kind of technical standards should be set as the minimums?_ _How detrimental is time delay in sending communications to a satellite and back?_ _What kind of ground transmitters and receivers would be needed?_ _How powerful or sensitive should they be?_ _Where should they be located?_ _How many satellites would be needed?_ _How much would all this cost?_ Satellite Design Problems _How big should a satellite be?_ _What should it be made of?_ _What color should it be?_ _What kind of power supply should it use?_ _How powerful should its electronic equipment be?_ _What should be its message-handling capacity?_ _What are the best receiving and transmitting antennas to use?_ _What frequencies ought to be employed?_ _What kind of modulation should be used?_ _How should signals be amplified?_ _What kind of telemetry equipment will be needed?_ _How can radiation in space be measured?_ Launching and Tracking Problems _How big a rocket booster would be needed?_ _From what part of the world should a satellite be launched?_ _What kind of orbit should it go into? (See table below)_ _How far up should the satellite go?_ _How can a satellite be tracked once it is in orbit?_ _How do we predict future orbits of a satellite?_ Orientation and Control Problems _How can orders be given to a satellite while it is in orbit?_ _If it is to stay in a fixed attitude, how can it be kept there?_ _What can be done to keep a satellite properly stabilized?_ _Can optical measurements be made on a satellite?_ _What will be the effects of sunlight and gravity on its position in space?_