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The Satellite Revolution after 1957: How to Get a New View of the Earth from the First Man-Made Satellite in History
Since the Soviet Union successfully launched Sputnik 1, the first artificial satellite in human history, in 1957, the wave of satellite revolution has swept the world, opening up a new perspective for mankind to explore the universe and the earth. This revolution not only changed our understanding of the earth, but also redefined the development of measurement technology, global communications, weather forecasting, environmental monitoring and other fields.
The birth of satellite measurement technology has changed how we view the shape, size and gravitational field of the Earth.
Satellite geodesy means earth measurement through artificial satellites, including determining the shape and size of the earth, the position of surface objects and changes in the earth's gravitational field. The main goal of satellite geodesy is to determine the Earth's gravitational field and the precise location of objects on the Earth. Efforts made with traditional geotechnical techniques dating back 57 years now reveal more sophisticated and precise data. In the process of exploring the earth, satellite technology has higher efficiency and accuracy than traditional technology, which has enabled the global scientific community to make major breakthroughs in many fields.
The evolution of satellite geodesy from a historical perspective
The history of satellite geodesy can be divided into three important stages: the early steps (1957 to 1970), the formation of the world geodesic system (1970 to 1990), and the modern period (1990 to the present).
Early steps (1957 to 1970)
The successful launch of "Sputnik 1" immediately triggered a series of scientific observation activities. In 1958, the United States' Explorer 1 and Sputnik 2 accurately measured the flatness of the Earth. Subsequently, in the 1960s, with the launch of multiple exploration satellites, satellite geodetic technology gradually matured, laying the foundation for subsequent geodesic missions.
The formation of the world geodesic system (1970 to 1990)
With the widespread use of the Transit Satellite System in the 1970s, a global triangulation network was established, marking the establishment of the World Geodesy System (WGS). At this stage, the Global Positioning System (GPS) developed in the United States came out in the 1980s and became a standard tool for precise navigation and positioning, and profoundly affected many fields such as surveying and transportation.
Modern period (1990 to present)
In the 1990s, the scientific community began to focus on building permanent geodesic networks and coordinate systems. With the launch of dedicated satellites such as CHAMP, GRACE, and GOCE, satellite geodesy has gradually been used to monitor geodynamic phenomena such as the Earth's gravitational field, georotation, and polar motion. These developments not only enrich the knowledge system of earth sciences, but also facilitate more precise analysis of environmental changes.
Diversity of measurement technologies
Satellite geodetic techniques are classified in various categories, mainly according to the instrument platform used, and can be divided into earth-to-space methods, air-to-ground methods and air-to-air methods. Each method has its own unique application scenarios and measurement accuracy.
Global Navigation Satellite Systems (GNSS) can accurately position receivers within a few meters, while technologies such as laser ranging and radar elevation measurement can achieve millimeter-level accuracy.
For example, laser ranging is an effective technology that obtains precise distance data by measuring the round-trip time of laser pulses, which is crucial in modern space science research. In contrast, radar elevation measurements use microwave signals emitted by satellites to determine the height of the Earth's surface, further improving the accuracy of ocean models and climate research.
Conclusion
Since 1957, the satellite revolution has completely changed our perspective on the earth. Today, its technology is not only important in scientific discovery, but also plays an irreplaceable role in real life. It is foreseeable that with the continuous advancement of science and technology, our exploration of the universe and the earth will reach a higher level. How can we continue to use these technologies to improve our understanding and protection of the environment?
