Artificial Earth satellite is an artificial spacecraft independently developed and manufactured by humans, which is sent into a space orbit dominated by the Earth's gravity through a carrier rocket and orbits the Earth. Unlike natural satellites such as the Moon, its core value is to provide various exclusive space application services for humans based on the unique environment of unobstructed space and high field of view.
Understanding artificial Earth satellites can be grasped from the following dimensions:
1. Orbit adaptation: According to mission requirements, satellites will be sent into different types of space orbits, such as low Earth orbit (with an altitude of several hundred kilometers, mostly used for remote sensing and scientific exploration), geosynchronous orbit (with an altitude of about 36000 kilometers, operating at the same angular velocity as the Earth's rotation, mostly used for communication and meteorological satellites), and sun synchronous orbit (with the orbital plane rotating with the Earth's rotation, ensuring stable illumination conditions for ground imaging).
2. Operational logic: The vast majority of satellites rely on the Earth's gravity to provide centripetal force for circular motion, with built-in attitude control systems to maintain flight attitude. Some satellites may carry small thrust engines to adjust their orbital position or avoid space debris.
Its various uses can be divided into the following categories according to application scenarios:
1, Communication relay service
As a space signal relay station, it enables cross regional and cross-border voice, data, and video transmission, such as synchronous orbit communication satellites supporting global satellite television, intercontinental communication, and ocean going ship communication; Low earth orbit communication satellite networking (such as Star Link, China's Hongyan Constellation) can provide global Internet access services without dead ends.
2, Remote sensing observation of the Earth
Equipped with optical, radar and other payloads to obtain information on the Earth's surface, the segmented scenarios include:
1. Meteorological monitoring: such as China's Fengyun series satellites, providing services such as weather forecasting, typhoon warning, forest fire monitoring, etc;
2. Resource exploration: such as high-resolution series satellites, used for land use surveys, agricultural yield estimation, and mineral resource exploration;
3. Environmental supervision: tracking environmental changes such as air pollution, eutrophication of water bodies, and glacier melting;
4. Emergency relief: Quickly obtain disaster images after earthquakes and floods to assist in rescue decision-making.
3, Navigation and positioning services
Build global or regional navigation systems that provide high-precision positioning, navigation, and timing services, such as China's Beidou-3, the United States' GPS, the European Union's Galileo, and other systems widely used in mobile navigation, autonomous driving, aviation and navigation, financial system time synchronization, and other scenarios.
4, Space Science Exploration
Carry out space environment research, astronomical observations, microgravity experiments, etc., such as China's Wukong dark matter detection satellite, practical series scientific experiment satellites, and the Hubble Space Telescope in low Earth orbit.
5, Technical validation and testing
Test new aerospace technologies, such as new propulsion systems, space materials, extravehicular operations, etc., to accumulate technical experience for manned spaceflight and deep space exploration.
6, Marine Special Monitoring
Specialized ocean satellites can monitor ocean water temperature, ocean currents, red tide, marine oil and gas development environment, etc., such as China's Haiyang-1 and Haiyang-2 series satellites.
