The Hubble Space Telescope (shown at the right) can be used for astronomy; Satellites are also important in navigation. With the Global Positioning System of satellites (GPS) shown below, a traveler can find his position anywhere on earth, using satellites. There are currently 24 satellites in the GPS system. There are also recognizance satellites, used for spying on other countries, and remote sensing satellites, which are used to monitor many things happening on the earth (through photos), such as animal migration, mineral deposits, etc. Satellites are used in search and rescue, to detect distress beacons and locate ships or planes that are in trouble. And we’ve all seen the use of weather satellites in meteorology. Any time you watch the weather on TV, you are looking at satellite photos. These weather satellites do a lot more than just give us photos of cloud cover; they give information about environmental and atmospheric conditions all over the earth.
New satellites are being launched all the time, by both government and private business. Because there is only so much space in the geostationary belt, there is increasing concern about a new kind of pollution; space garbage. A satellite does not last forever, as over time it starts to lose its ability to orbit. The result is a useless piece of technology that stays in space near Earth forever, unless it is retrieved.
