This is the satellite age, and countries the world over send their satellites into space for civilian and military purposes. The Global Positioning System (GPS) is a satellite navigation system. It has hundreds of civilian users across the world, but is developed and maintained by the US Department of Defense.

GPS was initially named NAVSTAR GPS by the US Department of Defense, and the first experimental satellite was launched in 1978. The constellation of satellites is under the 50th Space Wing, and in 2005 a new fleet of satellites were added to the constellation. GPS accuracy is improved by the use of Wide Area Augmentation System (WAAS) and Differential GPS. They improve GPS signal accuracy to within 2 meters and 1 cm, respectively.

GPS consists of three segments: constellation of satellites, monitoring network, and user receiving equipment. The first segment refers to satellites in orbit that provide information to the user equipment. This information is in the form of signals and data messages. The monitoring network or the operation control segment is concerned with tracking and retaining the satellites in space. It monitors battery power levels and propellant levels. It also keeps a tab on the health of satellites and the integrity of signals. In addition, it maintains the orbital status of the satellites and updates various parameters that help determine user position, time, and velocity.

The last segment, user receiving equipment performs functions like navigation, surveying, and timing. Earlier, this equipment was bulky, but today equipment of the size of a wrist watch is available. Parts of receiving equipment include antenna and receiver and processor. The equipment can be placed on ships, cars, and planes to provide accurate information regarding position, regardless of the weather. Receivers also gauge altitude and speed with a high level of precision.

GPS is widely used in navigation on land, water, and air. It also aids in creating maps and conducting land surveys. In addition, it enables tracking of vehicles and vessels and management of natural resources. GPS provides precise times and this helps in telecommunications and research, including studies on earthquakes.

GPS has lots of uses and does not appear to have any disadvantages. Therefore, it can be termed as a modern-day scientific wonder and safely used for civilian and military needs.