The Global Positioning System  Having a GPS unit handy has become an important part of driving and navigation. According to World Book Online, GPS is a worldwide navigation system that uses radio signals broadcast by satellites. This system is installed in many airplanes, cars, and boats, and has both military and civilian users. The availability of GPS has made navigation easier, safer, and quicker. History of GPS GPS has evolved over the years, going from strictly military use, to being used by the public. The first satellite system prior to the GPS was called Transit, which was created in 1964. Transit took about 30 minutes to calculate an individual’s position, which was inconvenient to many. The Department of Defense started developing ideas for a Global Positioning System in the early 1970’s. Their goal was to develop a system that would be used to help missiles find targets. The first GPS satellite was launched in 1978. The GPS was released in limited capacity to the public in the early 1980’s. The United States Air Force expanded upon the system to its fullest capacity in the early 1990’s, by launching the last of the 24 satellites in the Global Positioning System. At present, GPS is commonly used by everyone. Scientists are striving to improve this important navigation system. How GPS Works The Global Positioning System is comprised of a network of 24 satellites. Each satellite in space constantly transmits information to Earth about its position and current time.  Every GPS satellite has an atomic clock on board to keep precise time. When you search for directions to your destination, your GPS unit intercepts signals travelling at the speed of light. Then, based on how long it took for the messages to arrive, the GPS calculates how far away each satellite is. A single GPS unit uses signals from at least three, and often more, satellites. Once it has information on how far away you are from at least three satellites, the GPS can then detect where you are, using a process called trilateration, which is the overlapping of spheres to pinpoint your location. The more satellites there are above the horizon, the more accurately the GPS can calculate your location. Even though this is a complicated process, it is complete within a few seconds! The Impact on Our Lives Without GPS, navigation was extremely difficult and time consuming. Before the GPS was invented, travelers had to pull out giant, cumbersome maps, that weren’t very easy to follow.  It took quite a while to find your current location on the map. Trying to follow enormous maps while driving put the drivers and other cars on the road at risk. Now that GPS exists, drivers don’t have to worry about tracing their location. With the click of a button, their current location pops up on a screen in front of them. A large percentage of cars and cell phones have verbal GPS directions available, which allows drivers to focus on the road while they are driving to their destination. Search and rescue teams use GPS to help find people who are lost, and can’t find their way to safety. A high-tech system like GPS makes navigation more reliable and convenient. Navigation before GPS was very difficult and inconvenient to most people, but now that we have GPS, navigation is more dependable and timely. GPS has made driving safer and quicker for travelers, commuters, and vehicle drivers in general. Most drivers can pull out their mobile device, type in their destination, and have their directions within ten seconds. Today, GPS is saving lives, improving navigation, and helping society in countless other ways.