China launches twin satellites to test detection technology in space

The Wenchang Space Launch Site on the coast of the southern island province of Hainan saw the liftoff of two new satellites by China. According to Xinhua News, the Shijian-29A and Shijian-29B satellites were launched on December 31 at 6:40 a.m. (Beijing Time) aboard a Long March-7A carrier rocket and entered the designated orbit successfully. The satellites will be mainly tasked with processes related to new technology verification for space target detection, which, per Space Daily, usually entails on-orbit sensing, tracking, and characterization of space objects.

So far, detailed technical specifications have not been made publicly available, but the dual-satellite configuration is proof of certain experiments in space. These could include coordinated observations, navigating objects in relation to others, or formation-flying techniques to improve performance in space object surveillance.

As one of China's longest-running experimental satellite programs, the Shijian ("Practice") series is used to test new sensors, data links, technologies related to space environment, and propulsion systems before they get greenlit to become fully operational. Previous missions of Shijian and Shiyan carried payloads for space debris detection, space environment monitoring, and proximity operations. This shows how China uses test spacecraft technology to construct better infrastructure for space situational awareness.

Technologies for space target detection typically include optical imaging, infrared sensors, and radar or laser ranging systems. All the features are designed to pinpoint and distinguish satellites and debris across a wide array of orbits. Data from these missions can improve collision avoidance systems and catalog accuracy. Moreover, on certain occasions, it can even be used to support national security applications that need comprehensive knowledge of space assets. 

Developed by the China Academy of Launch Vehicle Technology under the China Aerospace Science and Technology Corporation (CASC), the Long March 7A launcher is a three-stage, medium-to-heavy class rocket that is built for high-energy orbits, including geostationary transfer and other demanding trajectories. CASC rockets have completed 73 missions this year, up from 51 last year, according to CGTN.  The latest launch marked the 623rd flight of the Long March series. The fact that the mission was launched from Wenchang, China's newest coastal spaceport, signals an ongoing shift of the country's most advanced space missions to the Hainan site, which offers better flight paths over open oceans.

The successful deployment of the Shijian-29A and 29B satellites in their target orbit underscores China's continued emphasis on technology verification missions that help draw long-term plans for a more informed presence in space. In many ways, it is also an important win for China, considering it failed at its second attempt at a reusable rocket test. Of course, more details about the payload suite, orbital behavior, and specific objectives of the latest mission are awaited. These details are expected to emerge in the coming months through tracking data and various official releases. 

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