Satellites also use :- A.) Civilian:- 1.observation (mapping, weather, forest cover, snow cover, ocean and earth temperature, pollution, urban development, etc.); Telescopes in different wavelengths, and transmitting 2.communication relays (Telecommunications, TV signals, etc.) 3.GPS. 4.space Living & experimentation: e.g. SpaceLab, ISS, teporary satellites such asT 5. Tracking of Aircrafts and ships (e.g. INMARSAT) B) Defence :- 1.as above: Recon, Communiction, GPS 2.launching attacks on other satellites (has been tested by US and China) 3.command and control 4.launching laser based defense (or attacks) C) Near future:- 1.launchpoint for future missions (especially to the ones for Mars) 2.reflection of comets heading towards Earth D) Distant future:- 1.zero Gravity & Cryogenic manufacturing of special materials 2.launching missile attacks (pretty expensive, as compared to Earth based strikes) 2.commercial exploitation of comets - currently very expensive, and don’t know useful minerals that could be mined effectively from known comets 3.source of Energy - microwaves to Earth safely is not an easy problem to solve, Sun energy .