A Predictive Guidance Algorithm for Autonomous Asteroid Soft Landing

Abstract

The objective of this work is to present a closed-loop guidance algorithm for landing a probe on an irregular shaped rotating asteroid. The main assumption is that the spacecraft is orbiting close to the asteroid and has a continuous propulsion system enabling it to do a powered descent. The goal is to minimize fuel consumption while avoiding collision with the asteroid during the manoeuvre. This non-convex time-continuous optimal control problem is transformed to a convex static program by relaxing some constraints, discretizing and using an iterative method to handle with the asteroid gravity field non-linearities. Then, a guidance algorithm based on Model Predictive Control is applied with the purpose of coping with unmodelled dynamics and disturbances. Numerical results are showed and discussed.