By definition a satellite is any object placed in orbit due to a gravitational pull of a larger entity. Since moons and some asteroids would fall under this description, the term artificial satellite was invented to describe man-made objects in space. Sputnik 1 was the first of its kind and launched by Russia in 1957, primarily to identify proper the proper launch coordinates required for later missions. Two months later Sputnik 2 successfully sent a dog named Lakia into space, and by this time the space race was fully ignited around the globe. Since that time thousands of other launches have occurred by over fifty separate countries. Only a few hundred of those artificial satellites are still operational, and within our orbit hundreds of partially damaged satellites continue to rotate around our planet as if they were inside a type of technological graveyard. If aliens have in fact visited our planet as so many people have attested over time, we must be viewed as the hillbillies of the universe since our space garbage has been left to idly drift for everyone to see.
There are countless uses for artificial satellites and they are relied on at all levels of civil and public government. Many will associate satellites for spying purposes, but they are also used for communication, global navigation, weather reporting, and other various types of research. From internet access and cellular telephones to GPS devices and television, satellites empower modern living as much as any twentieth century invention.
As useful as the technology appears, satellites are unfortunately a common object of attack as well. Militant groups will often hack into satellite transmissions in order to broadcast their own political views or to obtain classified secrets of another world nation. While the technology behind a satellite may appear advanced, it is no more than a computer designed to accept a variety of commands. Since communication requires a signal to be sent to and from Earth, it is relatively simple to block, intercept, or even take control of that transmission for personal gain. More sophisticated monitoring equipment has become available within the past decade to assist satellite operators to avoid these issues and quickly track the parties responsible, but the problem is far from being solved.
In astronomy, satellites have been used to view distant objects that would otherwise be inaccessible. The unmanned spacecrafts Pioneer and Voyager have been sent to the outer regions of our solar system and provided detailed analysis of Saturn, Uranus, Jupiter, and Neptune. At a total one way distance in excess of over four billion miles, these epic journeys have provided countless data for scientists on Earth and have helped explain the makeup of our solar system. A few examples of Voyager’s many scientific contributions are the discovery of water on one of Jupiter’s moons (Europa), erupting volcanoes on another (Lo), and a massive storm on Neptune that was previously undiscovered (the Great Dark Spot). Many of the highest resolution pictures of the outer planets have been provided by one of these two satellites, and without them our solar system would still be largely considered a mystery.