Trajectory reconstruction and black-out-area trajectory makeup for reentry capsules of spacecraft

For reentry capsules of spacecraft,making up the trajectory in black-out area is a key link of aerodynamic analysis from flight test data.One of effective methods for this problem is to reconstruct flight trajectory employing the onboard measurement data and the limited radar data.A mathematical model for the trajectory reconstruction is set up.It is composed of the kinematical model,the observation model,and the measurement error model.The trajectory reconstruction is thus transformed into the problem of parameter identification of a nonlinear dynamic system.The algorithm of trajectory reconstruction is derived based on the maximum likelihood criterion and Newton-Raphson iteration.The flight test data of some a reentry capsule are analyzed.The results validate the developed mathematical model and algorithm of trajectory reconstruction.The trajectory reconstruction not only makes up the trajectory in black-out area,but provides a complete set of reliable trajectory data.