China has started to construct an ultra-low orbit satellite constellation, said the developer China Aerospace Science and Industry Corporation (CASIC) on Wednesday at the 9th China (International) Commercial Aerospace Forum in Wuhan, central China's Hubei Province.

The constellation will comprise 300 communications and remote-sensing satellites orbiting the globe, providing a global ultrafast response capability within 15 minutes, said CASIC.

According to the construction plan, the first satellite in the constellation will be launched in December. The launch of a nine-satellite cluster for service verification is set to be completed in 2024, and a network of 192 satellites in orbit can be expected by 2027. By 2030, a total of 300 satellites will be in orbit for communication and remote-sensing services.

Currently, the design and production of the first prototype satellite have been completed. It will carry payloads including an optical remote sensing camera, a space-borne intelligent processing device and an atomic oxygen detector.

Very low Earth orbit

A very low Earth orbit (VLEO) refers to one with an orbital altitude of less than 300 km.

Compared with traditional orbits, the VLEO has a complex dynamic environment, which needs to offset the impact of the rapid decay of satellite orbital altitudes due to higher atmospheric resistance.

Despite many technical challenges in its long-term operation, the VLEO has high value.

The reduced orbital altitude helps turn Earth observation from "remote sensing" to "near observation," which contributes to lower cost, higher resolution and shorter transmission delays. It also helps reduce the weight and cost of optical payloads by 50 percent while providing the same resolution.

The constellation will achieve 0.5-meter spatial resolution and transmit spatial information to users within 15 minutes, Zhang Nan, chief designer of the constellation, told Xinhua News Agency.

It will be applied in emergency rescue, fire monitoring and disaster prevention and alleviation by providing real-time, effective data support.

"Once an emergency event occurs, it can capture and extract key information thanks to their inter-satellite transmission and intelligent processing capabilities, sending critical data through an independent network to terminals on Earth which could include a moving vehicle or portable devices," reported the Global Times.