Issue 43

China Launches Newest SAR Satellite

26 Feb 2022: China launched a Chang Zheng 4C (LM-4C) with the second Ludi Tance radar-imaging satellite from the Jiuquan Satellite Launch Center. The L-SAR 01B satellite now joins its predecessor, L-SAR 01A, in a sun-synchronous orbit. The two satellites are separated by 60 degrees. The two spacecraft are the first to…

26 Feb 2022: China launched a Chang Zheng 4C (LM-4C) with the second Ludi Tance radar-imaging satellite from the Jiuquan Satellite Launch Center. The L-SAR 01B satellite now joins its predecessor, L-SAR 01A, in a sun-synchronous orbit. The two satellites are separated by 60 degrees. The two spacecraft are the first to launch for a new Chinese civilian radar imaging constellation deployed in low Earth orbit. Launch Video.

– The satellites transmit L-band radio signals and record the echo as they are reflected from the surface of the Earth. By taking a series of measurements as it passes over an area of interest, a satellite can produce higher-resolution images with a relatively small antenna.

– The SAR payload on Ludi Tance-1 01B includes an antenna with an area of around 33 square meters.

– The stated objectives of the Ludi Tance satellites are to aid in resource monitoring, mapping, and disaster management. They are part of China’s National Civil Space Infrastructure Development Plan for 2015 to 2025.

– L-SAR 01B will realize on orbit networking with L-SAR 01A and build the world’s first L-band double star constellation.

– L-SAR 01 is a distributed SAR satellite system, which is composed of two L-band SAR satellites with the same design parameters. In orbit, it has two formation flight modes of “follow-up flight” and “around flight”.

– In the “follow-up” formation mode, the dual satellites’ primary task is surface deformation interferometry. The objective is surface deformation monitoring to support industrial applications such as land subsidence, landslide, ground collapse and seismic deformation to identify potential geological disasters in complex areas. It is also an important satellite resource for emergency investigation of earthquake disasters and major geological disasters.

– In the “fly around” mode, the two satellites realize close-range collaborative earth observation. With synchronized operations the satellites can produce high-precision ground elevation measurement and support natural resources surveys.

– This was the 40th flight of the Chang Zheng 4C and the 87th overall for the Chang Zheng 4 series.

– Chang Zheng 4 can launch from three of China’s four main launch sites, the Jiuquan, Taiyuan and Xichang Satellite Launch Centers. About three-quarters of Chang Zheng 4 launches have been from Taiyuan, with the rest flying from Jiuquan. Chang Zheng 4 can reach sun-synchronous orbit from either Taiyuan or Jiuquan.

Orbital visualization of the L-SAR 01 satellite pair.

Ludi Tance L-SAR satellite hardware during ground processing.

Connectable patches for L-SAR 01A and 01B, hinting at possible future satellites.