Abstract: To address the engineering challenge of calibrating the optical axes of two heterogeneous payloads—the thermal radiation spectrometer and the mid-field-of-view camera—in asteroid exploration, this paper proposes a dynamic spiral scanning and dual-source data fusion method. This method utilizes the Archimedean spiral trajectory generated by the helical motion of the probe platform as the excitation source, simultaneously acquiring the mid-field centroid sequence and thermal radiation energy sequence. Optical axis decoupling is achieved through spatiotemporal alignment and Gaussian surface fitting. Com-bining a target characteristic influence model, the quantitative impact of seven factors—diameter, shape, rotation axis, and thermal distribution—on calibration accuracy is systematically analyzed. To verify the feasibility of the method, a 15-meter ground-based full-physical simulation test system was designed. This system includes a probe simulation truss, a KR60-3 robotic arm, and a scaled-down asteroid model, reproducing the 20-kilometer on-orbit environment through geometric and kinematic equivalent design. Through quantitative analysis of the influencing parameters, 13 test conditions were ultimately determined to meet the thermal radiation imprint positioning requirements of the 600-meter station of the Tianwen-2 mis-sion. This method not only solves the problem of unifying the benchmarks of multi-source remote sensing data under low-light conditions of asteroids, but also provides a new, engineerable paradigm for my country's independent calibration tech-nology system for deep space exploration, and has the potential to be transferred to missions such as Jupiter system explora-tion.

Key words: Tianwen-2, asteroid exploration, optical axis calibration, Archimedes spiral scanning, thermal radiation spectrometer, mid-field camera