Soft Landing Trajectory Optimization on Asteroids by Convex Programming

This paper presents a strategy for the soft landing trajectory optimization on an asteroid. The interior gravity field model, a counterpart of the classical spherical harmonic model, is used to estimate the gravity acceleration near the target asteroid. This model has an advantage in computational efficiency and its convergence properties can be guaranteed within the constructed interior Brillouin sphere. The soft-landing optimization problem on an asteroid is converted into a successive second-order convex programming (SOCP) through constraints slack, linearization of dynamics and discretization which can be solved by the primal-dual interior-point methods. The numerical simulations shows that the lander arrives at the target site with zero velocity and all the constraints are satisfied. The fuel consumption is also optimal. Solving soft-landing optimization problem on an asteroid with convex programming has an advantage in computational effectiveness and can potentially be implemented in the future asteroid mission.