China Declassifies World’s Only Geostationary Earth Observation Satellite

On August 13, 2023, a Long March 3B rocket launched the Ludi Tance 4 01 (LT-4 01) civilian radar observation satellite into space from the Xichang Satellite Launch Center. This satellite became the world’s first geostationary Earth observation satellite. The technology was proposed in the United States in 1978, but China was the first to implement it in practice, which brought China to a leading position in radar technology.

Image source: CGTN

Experts associate the declassification of the Ludi Tanze-4 mission with China’s desire to demonstrate its superiority over Western partners in the field of high technology and space. The publication of a series of scientific papers on the project in the journal Space Science and Technology helps clarify a number of features of the radar’s operation in geostationary orbit (GEO). It uses synthetic aperture technology (SAR) and provides continuous observation of a third of the planet’s surface from an altitude of 36,000 km.

The radar monitors the Asia-Pacific region around the clock, which causes concern among neighboring countries and the United States, although the officially stated purpose of its work is to prevent earthquakes, as well as to help in agriculture and forestry.

According to previous leaks, LT-4 01 is capable of resolving objects on Earth as small as 20 meters. Achieving such resolution from GEO required the development of a whole range of technologies and solutions, including the “summation” of several beams in space, which is vaguely reminiscent of the technology of the Death Star from Star Wars. Unlike low-orbit remote sensing satellites, which provide more detailed images, LT-4 01 has a much larger surface coverage, although its data takes longer to process.

To accurately guide the radar from geostationary orbit, Chinese scientists had to develop unique stabilization mechanisms and signal processing algorithms. It is the algorithms that are called the main value of LT-4 01, since they allow the restoration of heavily distorted and partially blurred images of the planet’s surface.

«By declassifying core technologies, China is demonstrating to the world its superiority in electronic warfare, said a Chinese researcher who asked to remain anonymous. “Like the open-source models of AI company DeepSeek, this will force competitors to play catch-up in areas where China has a structural advantage.”