The high precision of GPS makes it an impressive technique for any imaginable application that requires the determination of positions (positioning), time (timing) and/or direction of motion (navigation) anywhere on Earth under all weather conditions. Although GPS is a relatively new technique, the highly creative minds of many people around the globe have already devised and developed a myriad of applications. The first applications were developed by the U.S. Department of Defense, who took on the assignment of designing and developing the GPS system. The applications in this category had a clear military orientation, like navigating combat airplanes, guiding missiles, positioning troops and locating military ships in a timely (real-time) manner.
Civilian applications, both commercial and scientific, already abound. In fact, commercial and scientific applications now far outnumber the military applications. We will mention just a few of them in the hope of stimulating the imagination of the freshest and most creative minds among the ATLAS participants to perhaps conceive new clever applications.
Reasonably enough, the GPS is helping more and more to guide cars and cabs, trucks and trains, sailing boats and ships, airplanes and even other satellites. Police and municipal services are using GPS for vehicle tracking. Rescue and salvation crews are using GPS to locate and speed the assistance to people during emergencies. Surveyors are using GPS to determine the boundaries, area, or elevations of land, rivers and/or countries. Engineers are using GPS to monitor the tiny motions and possible deformations of potentially hazardous structures such as bridges, roads and dams. Farmers are using GPS to survey their fields so that they can distribute fertilizer more efficiently. Airline pilots are using GPS to cruise and land airplanes. Hikers are using GPS to guide themselves on their mountain climbs. GPS systems are being extensively used on bicycle tours, marathon runs, rally competitions, and in many other kinds of sport events. Zoologists attach minuscule GPS receivers to penguins and polar bears, whales and dolphins, eagles and condors, lions and gazelles to study their behavior in their natural habitats. Cellular phones with GPS capabilities combine voice communication needs with positional information with the purpose of, for example, personal security and fleet management. Radio and television broadcasting stations, financial institutions and international transactions, computer networks and clocks around the world use the GPS signals for time synchronization. Backpack GPS units are being developed to guide blind people through the intricacies of the cities. The list goes on and on and on.
Applications of GPS in Science are becoming increasingly popular. For example, the timing information provided by GPS is being used atastronomical observatories around the globe to coordinate observation of celestial bodies such as planets, stars, galaxies and more exotic objects. Many space vehicles, such as the Shuttle or the Space Station, carry a GPS system for navigation purposes. Although the list here could also go on and on, we will concentrate on the Geosciences, that is, the scientific study of the Earth. We concentrate on this area not only because the Earth is our planet but also because the very nature of the global scale of the ATLAS experiments is directly related to this application.
A few applications of GPS within the Geosciences are:
The international collaborations described above could not be possible without a fast, powerful and reliable way of communication and data transmission like theInternet and electronic mail, or e-mail. Older methods of communicating data involved sending storage media through the mail. These methods are highly inefficient by todays standards. In fact, the volume of data exchanged on a daily basis over the Internet makes renders previous methods simply impossible to use.
TheInternet, a.k.a. the "Net," is a network of computers throughout the world that are linked together. The computers communicate with each other in very much the same way as people communicate with each other on the telephone, but very much faster. In fact, the physical link that connects many of the computers to the Internet is a regular telephone line. An important difference between the way people and computers communicate, though, is the language. Whereas people in different countries speak different languages and there are thousands of different languages spoken in the world, all computers speak one and the same language. This computer language is called "binary language."
The Internet includes, among other services, electronic mail and the World Wide Web. We will be using these two as part of the ATLAS Project. Electronic mail, a.k.a. e-mail, is a way to communicate using the Internet and is the most common way of sending short, quick messages between people using computers connected to the Internet. You only need to know the particular address where you want to "send" information by e-mail. E-mail addresses are even easier than postal addresses. For example, the email address of the ATLAS Project is email@example.com. You will send your messages to firstname.lastname@example.org and one of the scientists involved in the ATLAS Project will read them and respond to you. In this way, you are becoming a member of an international project that uses some of the most advanced technology available in Space and Earth communications.
The World Wide Web, a.k.a. the "Web," is made up of web sites. A web site consists of web pages which are stored in a particular computer. A web page is made up of almost any form of communication: text, images, movies, video, sound. Web pages are just ordinary computer files with pointers added to tell the computer some details about where to look for display and links. When you are using the Internet to search for any information in other computers you are said to be "navigating" or "surfing" the Web. Internet addresses are also easy. An example is the address you should type on your computer to visit the site that contains the information about the ATLAS Project. This address is:http://cfa-www.harvard.edu/space_geodesy/ATLAS/.
The Internet is like a huge illustrated library in which you can find information about almost anything imaginable. You can even post information about yourself if you want to make it available to everybody using it.
Worksheet for Students: Applications of the Global Positioning System
The students may complete the worksheetApplications of the Global Positioning System. This worksheet asks the students to design a system that incorporates GPS receivers. Students are encouraged to consider how GPS might be integrated into their daily lives.
In the next section we describe the first of the two ATLAS experiments, theGlobal Mapping Experiment (GME). By way of introduction to GME, the students will use hand-held GPS receivers to determine the position of their schools on the Earth and will exchange this information with their ATLAS participants around the globe. Very much like in a global scientific experiment, all the participating schools will be carrying out this experiment at nearly the same time. Timing and coordination are therefore important aspects of this experiment.
Space Geodesy Group Harvard-Smithsonian Center for Astrophysics 60 Garden St, MS 42 Cambridge, MA 02138-1516