A system using beamed and reflected radio signals to and from an object in such a way that range, bearing, and other characteristics of the object may be determined.
The motion of air relative to the earth's surface.
Periodic movements of animals in response to seasonal changes or reproductive instinct. Hormonal changes are the trigger in at least some animals. Most migrations are made for reasons of climatic change, feeding, or breeding.
The sixth planet in order from the sun. It is one of the five outer planets of the solar system. Its twelve natural satellites include Phoebe and Titan.
Devices, manned and unmanned, which are designed to be placed into an orbit about the Earth or into a trajectory to another celestial body. (NASA Thesaurus, 1988)
The use of wings or wing-like appendages to remain aloft and move through the air.
The environment outside the earth or its atmosphere. The environment may refer to a closed cabin (such as a space shuttle or space station) or to space itself, the moon, or other planets.
The solid substance formed by the FREEZING of water.