HELSINKI — China launched what is thought to be the world’s first geosynchronous orbit synthetic aperture radar satellite on Saturday.

A Long March 3B rocket lifted off from Xichang Satellite Launch Center in southwest China at 1:36 p.m. Eastern (1736 UTC) Aug. 12. The Land Exploration-4 01 (Ludi Tance-4 (01)) satellite successfully entered geosynchronous transfer orbit, the China Aerospace Science and Technology Corp., (CASC) announced within an hour of liftoff. 

Few details of the satellite were provided by CASC. However the group’s “blue book” outlining plans for 2023 released in January noted the launch of a “high-orbit 20-meter [resolution] SAR satellite.” 

The L-band synthetic aperture radar (SAR) satellite will provide all-day, all-weather observation of China and surrounding areas, boosting the country’s disaster prevention, reduction, and relief capabilities.

The land observation satellite series and “high-orbit SAR technology” are listed in the country’s Medium and Long Term Development Plan for Civilian Space Infrastructure (2015-2025). The plan includes establishing high and medium resolution optical and synthetic aperture radar constellations for a range of land, marine and atmospheric monitoring.

The series is separate from the China High-resolution Earth Observation System (CHEOS), which consists of Gaofen (“high resolution”) satellites. China’s Gaofen-4 satellite is a GEO optical satellite. SAR at GEO, while providing much lower resolution than satellites in low Earth orbit, can provide constant coverage and imagery despite cloud cover.

It is not yet known what orbital scheme the Land Exploration-4 (01) satellite will enter. An inclined GEO orbit would produce a “figure eight” ground track over the area of intended coverage. Chinese academics from the Beijing Institute of Technology have produced a study of various schemes, while others have published research into modified signal models for GEO SAR.

The (01) designation suggests China could launch other SAR satellites into geosynchronous orbits. The satellite was developed by the China Academy of Spacecraft Technology (CAST.)

The mission was followed early Monday by the launch of five automatic identification system (AIS) tracking satellites for HEAD Aerospace, which is affiliated to CASC.

A Kuaizhou-1A light-lift solid rocket lifted off from Xichang at 1:32 a.m. Eastern (0532 UTC) Aug. 14, official industry outlet China Space News reported.

The HEDE-3 A-E satellites join earlier satellites designed to obtain and transmit data for shipping and other maritime industries. 

The Kuaizhou-1A was provided by Expace, a spinoff from the China Aerospace Science and Industry Corp., (CASIC), a giant state-owned defense contractor.

The launches were China’s 35th and 36th orbital missions of 2023. CASC aims to launch around 70 times this year, while China’s commercial launch service providers are adding to Chinese activities. 

So far Galactic Energy, iSpace, Space Pioneer and Landspace, as well as state-owned commercial spinoffs CAS Space and Expace, have all reached orbit so far this year. Another, Orienspace, is targeting its first launch with the Gravity-1 solid rocket in December. 

Andrew Jones covers China's space industry for SpaceNews. Andrew has previously lived in China and reported from major space conferences there. Based in Helsinki, Finland, he has written for National Geographic, New Scientist, Smithsonian Magazine, Sky...