Rapid Generation of the Fuel-Optimal Trajectory for Landing on Irregularly Shaped Asteroids

In an asteroid soft landing mission, the irregularly distributed gravitational field and unexpected external disturbances may lead to a significant deviation of the actual landing trajectory to the predesigned trajectory. Therefore, the capability of trajectory onboard generation is essential to meet the requirements of landing accuracy and safety. To this end, this article proposes a rapid trajectory generation algorithm for the fuel-optimal asteroid landing. First, two important properties of the fuel-optimal landing trajectory are revealed in detail with the presented theorems. Then, based on these properties, the problem of landing trajectory generation is transformed into an onboard parameter searching problem, which is of significant benefit for the real-time performance and convergence. The effectiveness of the proposed algorithm is verified through the 433 Eros soft landing mission based numerical simulations. It is shown that the proposed fuel optimal asteroid landing trajectory generation algorithm is valid with deviated initial conditions and irregularly distributed gravitational field.