摘要：The precise orbit of the Hayabusa2 spacecraft with respect to asteroid Ryugu is dynamically determined using the data sets collected by the spacecraft’s onboard laser altimeter (LIght Detection And Ranging, LIDAR) and automated image tracking (AIT).The LIDAR range data and the AIT angular data play complementary roles because LIDAR is sensitive to the line-of-sight direction from Hayabusa2 to Ryugu, while the AIT is sensitive to the directions perpen‑ dicular to it.Using LIDAR and AIT, all six components of the initial state vector can be derived stably, which is difcult to achieve using only LIDAR or AIT.The coefcient of solar radiation pressure (SRP) of the Hayabusa2 spacecraft and standard gravitational parameter (GM) of Ryugu can also be estimated in the orbit determination process, by combin‑ ing multiple orbit arcs at various altitudes.In the process of orbit determination, the Ryugu-fxed coordinate of the center of the LIDAR spot is determined by ftting the range data geometrically to the topography of Ryugu using the Markov Chain Monte Carlo method.Such an approach is efective for realizing the rapid convergence of the solution. The root mean squares of the residuals of the observed minus computed values of the range and brightness-centroid direction of the image are 1.36 m and 0.0270°, respectively.The estimated values of the GM of Ryugu and a correction factor to our initial SRP model are 29.8±0.3 m3 /s2 and 1.13±0.16, respectively.
关键词：Hayabusa2; Precise orbit determination; LIDAR range data; ONC image tracking data; GM of Ryugu; Solar radiation pressure
