Detailed 3D Surface Reconstruction of Asteroids by Integrating Stereo Photogrammetry and Stereo Photoclinometry

3D models of asteroids provide their physical properties, such as shape, size, and surface features, which are of great importance to asteroid exploration missions and scientific research. The stereo photoclinometry (SPC) technique retrieves detailed surface topography of asteroids based on the reflectance information embedded in the image intensity of each pixel, thus the assessment of its performance is essential before the launch of the mission spacecraft. This work presents a laboratory experiment to evaluate the high-resolution and high-precision 3D surface models of asteroids reconstructed through an integrated photogrammetric and photoclinometric approach using simulation images. The whole experiment involves 3 steps. Firstly, construct the scaled-down experimental fields to simulate real in-situ conditions of the space probe with 3D printed models of asteroids, which represent the target asteroids of future missions. Then, collect simulation data according to various scenarios that might be encountered in a real on-orbit mission. Finally, reconstruct detailed asteroid models through the SPC refinement approach on the basis of stereo photogrammetry (SPG) models. Our previous studies indicate that SPC performance is influenced by both the azimuth and the incidence angles of illumination, as well as the image's general intensity. The experiment takes all these factors into account, as a reference for improving the image-acquiring plan during the in-situ detailed survey phase. The integrated approach will be tested for pixel-wise surface reconstruction of 3D-printed asteroid models of different shapes, i.e., Itokawa and Bennu. According to initial experimental results, the developed approach demonstrates the capability to attain high geometric accuracies and capture fine small-scale topographic details, which fulfills the requirement of the asteroid exploration missions.