The great world powers have always engaged in a fierce technological battle in the space domain, a competition whose beginnings date back to the end of the Second World War. If the United States has long dominated this race with its emblematic successes, from the historic Apollo 11 moon landing in 1969 to the Voyager probes of the 1970s, to the prowess of the Hubble telescope, the horizon has changed significantly in recent decades.
India has successfully placed several probes on the Moon, including Chandrayaan-3 which marked a historic feat by reaching the lunar South Pole. Japan has also sent probes to Venus, Mars and several asteroids. Another country, once considered a real outsider in the space race, is today on the front line: China. The latter has had a string of successes for several years: the Chang’e 4 probe which landed on the far side of the Moon in 2019, construction of its own Tiangong space station (CSS) in 2022 or Martian missions with the Tianwen probe -1. The country is therefore neck and neck with the major space powers, alongside the United States and Europe. Beijing is innovating this time in a completely different area: terrestrial observation by autonomous satellites.
Satellites without humans at the controls
The Shanghai Academy of Spaceflight Technology (SAST) has just launched from the base of Jiuquan, Inner Mongolia, two twin satellites Gaojing-2 03 and 04 aboard a Long March-2C rocket. Unlike conventional satellites which are constantly guided and monitored from Earth, these new spacecraft can stand on their own.
These two little jewels are capable of maintaining their position within a radius of approximately 100 meters and of coordinating their movements with precision less than one meter.
How does it work?
Gaojing-2 03 and 04 are equipped with a synthetic aperture radar (SAR), which emits polarized electromagnetic pulses towards Earth. By analyzing their return time, they generate images of exceptional precision. This approach marks a break with traditional observation systems: where traditional optical sensors come up against meteorological and nighttime limitations, this type of radar allows continuous observation of the territory, whatever the conditions.
Satellites can thus map the earth’s surface day and night, through clouds and bad weather. Unlike optical sensors which simply capture light reflected from the earth’s surface, SAR radars themselves emit radio waves. These waves penetrate clouds and can be used day or night. Neither clouds, rain or snow can affect them.
The United States certainly maintains its lead in certain areas, notably thanks to innovations from SpaceX (orbital refueling or recovery of propellants on the ground). However, the emergence of these Chinese satellites testifies of a gradual shift in the balance of power in the aerospace sector. Beijing’s colossal investments undertaken since the 1990s in its space program have enabled China to pass from the status of imitator to that of innovator. Today, it is the only one to have launched this type of satelliteeven if several countries are already working on prototypes equipped with SAR radar such as the United States, Canada or Japan.
- China has deployed fully autonomous satellites, an unprecedented technological advance in space observation.
- The Gaojings integrate an RSO radar, guaranteeing precise ground surveillance in all conditions, day and night.
- This innovation confirms the rise of China, now a major player in the aerospace sector.
