A communications satellite is an artificial satellite that relays and amplifies radio telecommunications signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Satellite communications networks servicing large number of users comrise of  user terminals, satellites and a ground …

Like the British Royal Navy more than a century before it, the U.S. Navy has a command of the sea that affords the United States unrivaled international influence.  By its use of the sea, which covers nearly three-quarters of the earth, a navy can do things that land-based forces cannot. …

The electromagnetic pulse commonly abbreviated as EMP, is a high-intensity burst of electromagnetic energy caused by the rapid acceleration of charged particles, can be produced by intense solar storms or by a nuclear weapon detonated high in the atmosphere. For example, solar geomagnetic storms (geomagnetic disturbances or GMD) create immediate …