LuTan-1 (LT-1) is the first civil L-band synthetic aperture radar (SAR) satellite constellation and comprises two identical satellites. LT-1 is designed to fulfill two main requirements, one of which the main tasks is to provide digital surface model (DSM) products covering the areas that are not available using optical satellites. The second task is to provide deformation products to support the geohazard monitoring task. For the first task, LT-1 provides a novel noninterrupted imaging technology to facilitate phase synchronization. For the second task, the orbit maintenance is implemented using a newly proposed in-plane offset semimajor axis and out-of-plane control triggered strategy. Besides, we provide the system performance analysis for the two main tasks. Finally, the first results are produced with root-mean-square-error (RMSE) of the DSM less than 0.7 m in the flat region and 6.7 m in the mountainous region. The RMSE of the first deformation products is less than 2.7 mm in the test region. The results indicate a favorable potential for terrain mapping and deformation monitoring applications.

LuTan-1(LT-1) has finished its in-orbit test in 2023. The inorbit test results show that LT-1 performed well and fulfilled the needs of the users. In order to use the data operationally for natural resources monitoring, especially for geohazard monitoring, we have established the application system for LT-1. In this paper, we have introduced the application system including the geometric technology, the standard products generation method, the basic deformation products generation method. Demonstrations of LT-1 are also provided to support the applications of the satellite data.

The Kinematics of rock glaciers is a key indicator for studying periglacial environment hydrology, climate, and disasters. Differential Interferometric Synthetic Aperture Radar (DInSAR) has been demonstrated to be an effective technique for detecting the deformation of rock glaciers. In this study, we present an investigation of the potential of the Lutan-1 (LT-1) SAR constellation for rock glacier topography mapping and deformation monitoring over a periglacial environment with complex topography using Stacking InSAR methods. Firstly, a high-resolution digital surface model (DSM) is generated by the bistatic formation data of the LT-1 SAR constellation. Compared with the ICESat GLAS points elevation product distributed in the study area, the R2reached 0.96, and the root mean square error (RMSE) reached 1.6m, indicating the accuracy of the LT-1 derived DSM product. Then, the deformation velocities of the rock glaciers were acquired from the Stacking InSAR method over the study area. The results indicated that the LOS deformation velocities of rock glaciers in the study area ranged from −0.8 m/y to approximately 0.6 m/y, with an average velocity amplitude of 0.06 m/y. With 241 of the rock glaciers exhibit active zones. The results demonstrated that the LT-1 SAR constellation could provide a new SAR data source for periglacial landform topography mapping and deformation monitoring.

A collapse accident occurred in the Alxa left Banner open-pit mining area of Inner Mongolia on February 22, 2023, causing heavy casualties and property losses. Multi-temporal pre-collapse and post-collapse images were acquired by the Lutan-1 SAR satellites, which is the first group L-band SAR constellation in China. The subsidence information of pre-collapse and post-collapse were extracted and analyzed, which provides certain knowledge for post-disaster accident handling and emergency response. Due to the extensive mining activities, the topography of open-pit coal mine area generally changes obviously. TanDEM and Gaofen-7 DEM were employed for deformation monitoring. The results indicated that time-efficient DEM is necessary for open-pit mining area monitoring. At the same time, based on the subsidence information detected before the disaster with high spatial and temporal resolutions, combining with prior information and expert interpretation, it is potential to provide certain support for the early hidden danger identification.

The L-band differential interferometric SAR satellite, also named as LuTan-1, is the first bistatic spaceborne L-band SAR constellation for multiple applications in China. The Datong, Yulin and Liupanshui coalfields are the main coal production base in China which produce over 100 million tons coal each year and play a significant role for the development of national economy. However, a series of issues such as ground subsidence, landslides and damage of structures are induced by extensive coal mining. Therefore, the preliminary assessment of LuTan-1 SAR data for mining deformation monitoring, including Datong, Yulin and Liupanshui coalmines in China, were implemented in this research. Owing to the high revisit ability and long wavelength of LuTan-1 satellites, obvious subsidence was detected for different coalmines using LuTan-1 SAR data. In comparison with the simultaneous leveling measurements, deformation monitoring with cm accuracy were achieved over the study area.