Inverse Calculation and Regularization Process for the Solar Aspect System(SAS) of HXI Payload on ASO-S Spacecraft

For the ASO-S/HXI payload, the accuracy of the flare reconstruction is reliant on important factors such as the alignment of the dual grating and the precise measurement of observation orientation. To guarantee optimal functionality of the instrument throughout its life cycle, the Solar Aspect System (SAS) is imperative to ensure that measurements are accurate and reliable. This is achieved by capturing the target motion and utilizing a physical model-based inversion algorithm. However, the SAS optical system’s inversion model is a typical ill-posed inverse problem due to its optical parameters, which results in small target sampling errors triggering unacceptable shifts in the solution. To enhance inversion accuracy and make it more robust against observation errors, we suggest dividing the inversion operation into two stages based on the SAS spot motion model. First, the as-rigid-aspossible (ARAP) transformation algorithm calculates the relative rotations and an intermediate variable between the substrates. Second, we solve an inversion linear equation for the relative translation of the substrates, the offset of the optical axes, and the observation orientation. To address the ill-posed challenge, the Tikhonov method grounded on the discrepancy criterion and the maximum a posteriori (MAP) method founded on the Bayesian framework are utilized. The simulation results exhibit that the ARAP method achieves a solution with a rotational error of roughly±3 5 (1/2-quantile);both regularization techniques are successful in enhancing the stability of the solution, the variance of error in the MAP method is even smaller—it achieves a translational error of approximately±18μm (1/2-quantile) in comparison to the Tikhonov method’s error of around±24μm (1/2-quantile). Furthermore, the SAS practical application data indicates the method’s usability in this study. Lastly, this paper discusses the intrinsic interconnections between the regularization methods.

Hard X-ray Imager (HXI) onboard the ASO-S mission

Hard X-ray Imager(HXI)is one of the three scientific instruments onboard the Advanced Spacebased Solar Observatory(ASO-S)mission,which is proposed for the 25th solar maximum by the Chinese solar community.HXI is designed to investigate the non-thermal high-energy electrons accelerated in solar flares by providing images of solar flaring regions in the energy range from 30 keV to 200 keV.The imaging principle of HXI is based on spatially modulated Fourier synthesis and utilizes about 91 sets of bi-grid sub-collimators and corresponding LaBr3 detectors to obtain Fourier components with a spatial resolution of about 3 arcsec and a time resolution better than 0.5 s.An engineering prototype has been developed and tested to verify the feasibility of design.In this paper,we present background,instrument design and the development and test status of the prototype.

Panoramic camera on the Yutu lunar rover of the Chang'e-3 mission

The Chang＇e-3 panoramic camera, which is composed of two cameras with identical functions, performances and interfaces, is installed on the lunar rover mast. It can acquire 3D images of the lunar surface based on the principle of binocular stereo vision. By rotating and pitching the mast, it can take several photographs of the patrol area. After stitching these images, panoramic images of the scenes will be obtained.Thus the topography and geomorphology of the patrol area and the impact crater, as well as the geological structure of the lunar surface, will be analyzed and studied.In addition, it can take color photographs of the lander using the Bayer color coding principle. It can observe the working status of the lander by switching between static image mode and dynamic video mode with automatic exposure time. The focal length of the lens on the panoramic camera is 50 mm and the field of view is 19.7？umination and viewing conditions, the largest signal-to-no×14.5？.Under the best illise ratio of the panoramic camera is 44 d B. Its static modulation transfer function is 0.33. A large number of ground testing experiments and on-orbit imaging results show that the functional interface of the panoramic camera works normally. The image quality of the panoramic camera is satisfactory. All the performance parameters of the panoramic camera satisfy the design requirements.