Navigatsioonisatelliit

A navigation satellite, also known as a navigational satellite, is an artificial satellite used to provide autonomous geo-spatial positioning. These satellites are a critical component of satellite navigation systems, which are used for various applications such as aviation, maritime navigation, and land-based transportation. Navigation satellites are typically part of a constellation of satellites that work together to provide global coverage.

The primary function of a navigation satellite is to transmit signals that can be received by ground-based receivers. These signals contain information about the satellite's position and the time at which the signal was transmitted. By receiving signals from multiple satellites, a receiver can determine its own position, velocity, and time with high accuracy.

Navigation satellites are typically placed in medium Earth orbit (MEO), at an altitude of approximately 20,000 kilometers. This orbit allows the satellites to provide global coverage and ensures that a receiver can always see at least four satellites, which is the minimum number required to determine a position in three dimensions.

The most well-known navigation satellite systems include the Global Positioning System (GPS) operated by the United States, the GLONASS system operated by Russia, the Galileo system operated by the European Union, and the BeiDou system operated by China. Each of these systems uses a constellation of satellites to provide navigation services to users around the world.