[PPS03-P11] Use of Hayabusa2/LIDAR range data to improve spacecraft trajectory for landing site selection
Keywords:Hayabusa2, LIDAR, orbit correction
Given the initial (or erroneous) spacecraft trajectory with respect to the asteroid, the spacecraft attitude information, the observed LIDAR ranges, and the shape model together with asteroid spin information (orientation and period), one can calculate LIDAR footprint positions in asteroid-fixed frame. At the initial stage of the proximity operation, the trajectory errors can be in the order of several tens of meters or sometimes more than a hundred meters, and then considerable deviations will be observed between the calculated LIDAR footprints and the shape model. By assuming that these deviations are mainly due to the trajectory error, orbit correction can be obtained from the residual time series. One simple way is to rotate the residual vectors from Ryugoid-fixed frame to J2000 frame and fit quadratic functions for each of X, Y, Z components of the time series. In the LSS training, this idea worked to some extent, and we were able to quickly provide the improved trajectory to LSS analysis team. In the training, however, point-wise LIDAR footprints as well as a perfect pointing of the LIDAR (zero alignment error) are assumed. We will report how these idealizations affect the results.