Hello David,   Thank you for your letter inquiring about communication satellites.  I will try to answer your questions.     1.) What is the most important impact of comsats on the daily life of people?         Many people receive all of their television by using comsats.  Comsats are in heated competition with cable systems for this purpose.     2.) What was the keystone in starting communication satellites?         The early motivation was the provision of more telephone circuits than were available with the cable or microwave systems of the time.     3.) What would life be like without comsats?         For most of us, life would be the same.  However, some people in rural areas and remote islands would have no television or Internet access.  Aircraft flying over the oceans would have no telephone service.  Nationwide radio service, as is being provided by XM and Sirius satellite, would not be available.     4.) Do you feel that the comsats we have can be improved?         Yes, improvements are always being made, mainly in the number of channels or circuits being provided.  Improvements also are being made in beaming specific channels to specific areas or countries.     5.) What is the biggest danger that comsats have brought to the world?         I don't know of any.     6.) Could anything we have now replace comsats in the long run?         See my answer to 3. above.  Cable systems, especially optical fiber, can replace comsats in many other cases.     7.) What is the best thing that comsats have given us?         Comsats are providing an economical way of distributing television programming and high speed data communications around the world.  They are doing this in many cases at a lower cost than competing cable services.  To use a comsat, however, one must have a direct line of sight path available to the satellite.  Trees and buildings block the signal.  For this reason, people in large cities may have to use cable systems instead. These are very brief answers to your questions.  In fact, whole books have been written discussing the types of questions you are raising. Best wishes for a successful History Day.   Sincerely, Bernhard E. Keiser