Belt of Needles

an artificial formation injected into orbit around the earth and consisting of short thin copper or tungsten wires, or dipoles, ejected from the capsule of an artificial earth satellite. It can be used as a passive reflector with nondirectional scattering in a radio relay communication system. Two belts—one in the equatorial plane and the other in the polar plane—at an altitude of approximately 4,000 km are sufficient for communication between any two points on the earth. The belts have a useful life of several years and are reliable and inexpensive. They scatter, however, just a small fraction of the energy of radio signals, and their maximum message-transmission rate is low. They may pose dangers to artificial earth satellites.