Since ancient times, humans have been fascinated by the stars in the sky. They have looked to them for navigation, weather forecasting, and spiritual guidance. Thousands of years later, we continue to explore and learn from space. One way we do this is by using satellites orbiting Earth to help us with land surveying. There are many different satellite constellations worldwide that are used for this purpose. In this blog post, we will take a closer look at some of them.
Global Positioning System (United States)
Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) that provides location and time information in all weather conditions, anywhere on or near the Earth’s surface. It is run by the United States Air Force under the control of the United States Space Force and has 31 satellites currently in orbit.
GPS consists of three areas:
- The space segment consists of a constellation of satellites orbiting the Earth.
- The control segment consists of ground stations that monitor and control the satellites.
- The user segment, which are the GPS receivers used by people and equipment to receive and use the GPS signal.
The GPS signal can be received by anyone with a GNSS receiver, regardless of their location on or near the Earth’s surface. GNSS receivers use the signals from four or more satellites to calculate their position, velocity, and time.
GPS was developed by the United States Department of Defense in the 1970s as a way to improve navigation and timing for military purposes. The Global Positioning System became fully operational in 1993, and the first civilian GNSS receiver was built in 1989.
Since then, GNSS has become widely used for navigation and timing applications by civilians and businesses around the world. It is also used extensively in the United States for navigation by cars, boats, aircraft, and other vehicles. The Global Positioning System is a vital infrastructure component in the United States and worldwide.
GLONASS (Global Navigation Satellite System) is a Russian Global Navigation Satellite System, providing autonomous navigation, positioning, and timing services worldwide.
The first satellite of GLONASS was launched in 1982, and since then 24 GLONASS satellites have been successfully put into orbit. The system provides real-time position and velocity determination for objects on or near the Earth’s surface at ranges up to 2500 km.
GLONASS is operated by the Russian Federal Space Agency, Roscosmos. Development of GLONASS is carried out with the participation of enterprises and organizations of the Russian space industry. There are three main constellations of GLONASS satellites: Uragan, Molniya, and Tsiklon.
The Galileo Global Navigation Satellite System is the European Union’s version of GPS. It is a global navigation system that provides accurate positioning and timing information for users on the ground, in the air, and at sea.
Galileo is managed by the European Commission and operated by the European Space Agency (ESA). The system was designed to provide an independent, high-precision positioning and timing service for Europe. In addition to its civilian applications, Galileo also has potential military uses.
The first two ground centers went live in 2016, and as of December 2021, there are 22 satellites in orbit, with a further two satellites to be activated by the end of 2022. Galileo has 30 satellites in orbit, 24 of which will be active at any given time.
Galileo is open to all users and is free of charge. It is compatible with GPS and can be used as a complement to or a replacement for GPS.
BeiDou, also known as BeiDou Navigation Satellite System (BDS), is a Chinese satellite navigation system. It is operated by the BeiDou Navigation Satellite System Corporation, which was founded in 2000. BeiDou is the fourth Global Navigation Satellite System (GNSS) after GPS, GLONASS, and Galileo.
The BeiDou system consists of two separate satellites constellations: BeiDou-1 and BeiDou-2. The first BeiDou-1 constellation was launched in 2000 and consisted of three satellites. The second constellation, BeiDou-2, was launched in 2012 and consists of 10 satellites. BeiDou-3 was launched in 2015, with the final satellite being launched into orbit in 2020. Currently, there are over 35 BeiDou satellites in orbit.
The main purpose of the BeiDou system is to provide positioning and timing services for users in China and other Asian countries. BeiDou has several advantages over other Global Navigation Satellite Systems. For example, it has higher accuracy and reliability and is less susceptible to interference. In addition, BeiDou is designed to be compatible with GPS, which means that users can receive signals from both systems.
There are a few different satellite positioning constellations in the world, Global Positioning System (GPS) being one of them. GPS is jointly owned by the United States government and operated by the Space Force and has been operational since 1995 with over 31 satellites in orbit. GLONASS, or Global Navigation Satellite System, is Russia’s equivalent to GPS and has been operational since October 1982 with over 24 active satellites.
Galileo is the EU’s proprietary navigation system. It was established in 2016 and has 30 satellites in orbit. BeiDou Navigation Satellite System (BDS) is China’s answer to global navigation, having started service in 2000 with over 35 satellites. There are other systems as well, but these are the most predominant ones used around the world for land surveying.