Large-scale deployment of China’s commercial remote sensing radar constellation of 12 satellites began on Monday, according to PI ESAT, a Beijing-based satellite company.
The announcement came after the four PIESAT-2 satellites, which were launched into a 528-kilometer sun-synchronous orbit last week, were calibrated and successfully transmitted high-resolution images and data to Earth.
The new satellites join eight other satellites that have been launched previously, creating China’s largest commercial remote sensing radar constellation: Nuwa, which is named after the Chinese goddess known as the creator of humanity.
The Nuwa satellites are arranged in three groups in orbit. The first group forms a wheel-like configuration with the main satellite acting as a “hub” surrounded by three auxiliary satellites evenly spaced. The second and third groups were launched over the past two months and are organized into four-satellite, coorbital, wheel-shaped constellations.
The constellation is now able to provide global coverage, including polar and equatorial regions, and can see through clouds and rain, thus providing all-weather continuous observation of the Earth with an image resolution of up to 1 meter.
“The satellites provide instant remote sensing with rapid response and flexible surveillance capabilities,” said Wang Yuxiang, chairman of PIESAT. “They take only 20 minutes to transmit data from the team to the ground receiver.”
Synthetic Aperture Radar (SAR), a satellite-mounted interferometric radar, can take two images of the same area by bouncing radar signals off the earth’s surface at different times. By causing the images to interfere with each other, they create maps, called interferograms, that show the displacement of the earth’s surface between the two time periods.
By 2025, the Nuwa constellation is expected to have a network of at least 20 satellites, enabling daily interval visits, with the fastest visit time reduced to an hour.
The PIESAT team has also applied artificial intelligence (AI) technology to improve the efficiency of image analysis, monitoring millimeter-scale deformations on objects such as dams, landslides and drainage outlets in real time.
In July of this year, four PIESAT satellites in orbit provided radar images and data to support rescue efforts following a dam break on Lake Dongting, China’s second largest freshwater lake.
Following the dam breach on July 5, the satellites conducted four rounds of high-frequency surveillance from July 7 to 11. “The ability of the satellites to operate in adverse weather conditions ensured that critical data was collected at crucial moments,” said Huang Jinhai, vice president of PIESAT.
In the future, the Nuwa project aims to create an interconnected platform of 114 satellites to form a larger hybrid SAR constellation.
According to Mr. Wang, the current constellation can provide data and images for flood control, water resource monitoring, construction safety, agricultural surveillance, and ocean observation.
