Artificial Satellite

A human-made object orbiting Earth, a core space technology used for communication, navigation, observation, scientific research, and other purposes.

Artificial Satellite

Overview

An artificial satellite is a human-made object placed into Earth orbit or orbit around another celestial body by a rocket. Beginning with the Soviet Union's Sputnik 1 (스푸트니크 1호) in 1957, humanity has launched satellites for a wide range of purposes, including communications, navigation, weather observation, military reconnaissance, and scientific research. Today, artificial satellites are a key element supporting modern society's communications, transportation, and disaster-response infrastructure, and their number and roles are expanding rapidly with the growth of the space industry.

Key Details

Types of Orbits

A satellite's mission is largely determined by its altitude and orbital shape. Low Earth orbit (LEO, about 200–2,000 km) is suitable for Earth observation and satellite internet; geostationary orbit (GEO, about 35,786 km) matches Earth's rotation speed and thus appears fixed over one point, so communications and weather satellites mainly use it. Medium Earth orbit (MEO) between them is used for satellite navigation systems such as GPS, while polar orbit and sun-synchronous orbit are advantageous for observing the same area at a consistent time. Elliptical orbits are also used for intensive observation of polar regions or specific areas.

Components

A satellite is broadly divided into the payload and the satellite bus. The payload consists of equipment that performs the actual mission, such as cameras, communication transponders, and sensors, while the bus comprises systems that support stable satellite operation, including the power system (solar panels and batteries), attitude control system, propulsion system, thermal control system, and communication and command system. In recent years, miniaturization and modularization have advanced, and very small satellites such as CubeSats are also widely used.

Launch and Operations

Satellites are inserted into orbit by multistage rockets, and after launch they continue orbital adjustments, attitude control, and mission operations through communication with ground stations. A satellite's lifetime is determined by factors such as fuel quantity, component lifetime, and orbital environment; satellites that have reached the end of their life are either burned up by re-entering the atmosphere or moved to a graveyard orbit for disposal. Recently, satellite constellation operations and automated collision-avoidance technology have become increasingly important.

Applications

Communications: broadcasting, telephone, and internet services, especially communications in remote areas, at sea, and in aviation
Navigation: satellite navigation systems such as GPS, GLONASS, Galileo, and BeiDou
Earth observation: weather forecasting, disaster monitoring, and agriculture, forestry, and ocean monitoring
Science: astronomical observation, space environment research, and measurement of Earth's magnetic and gravitational fields
Military and security: reconnaissance, early warning, and communications relay

Space Debris Problem

As the number of satellites has surged, space debris such as defunct satellites and fragments has emerged as a major international issue. To respond to the increased risk of collisions and concerns about Kessler syndrome, discussions are actively underway on deorbit devices, space situational awareness (SSA), and international norms.

Latest Trends

In 2024–2025, large-scale low Earth orbit satellite constellations (mega-constellations) became a central topic in the space industry. Satellite internet operators, including Starlink, are expanding global broadband services by operating thousands of satellites, and governments and private companies around the world are also building their own satellite networks. As reusable launch vehicles become common and launch costs drop significantly, very small satellites and private-led space development are accelerating, and AI analysis services using satellite data are also growing rapidly. In addition, inter-satellite laser communications, on-board AI processing, and space situational awareness and automated collision-avoidance technology are emerging as core competitiveness for next-generation satellites. In Korea as well, policies to foster private space companies are continuing while strengthening independent launch vehicle and satellite development capabilities.