Joshua Moriarty, age 14, of Biloxi, Miss., for his question:

HOW DOES A COMMUNICATIONS SATELLITE WORK?

A communications satellite is used to relay radio, television, telephone or other electronic communications to any part of the world.  These satellites are placed in a geosynchronous orbits at 22,550 above the equator.  At this distance its orbital velocity maintains the satellite at a single point relative to the earth rotation.

Unmanned rockets launch the satellites into earth orbits, or they are sent into action from one of our space shuttles. Then ground stations beam signals to the satellites by means of special antennas. The satellites send the signals back to various receiving stations on earth. Because of their position high above the planet, the satellites permit links between ground stations that would otherwise be separated by too much distance to communicate with each other.

Communication by satellite is also much more reliable than by ordinary short wave radio, and it also has better quality. The satellites also carry a wider range of radio frequencies or wave lengths than short wave radio can.