Landing Guidance Strategy of Space Rider

Abstract

Space Rider is the European program proposed to develop an affordable and sustainable reusable space transportation system to enable access to and return from space. To procure a safe and accurate landing, Space Rider will use a large deployable parafoil to fly autonomously upon the landing site. The landing guidance algorithm is based on two preselected waypoints and enables the system to reach the target landing site with high accuracy and being adaptive to wind knowledge errors, turbulence, and uncertainties on the main characteristics of the system, such as aerodynamics, sensors, and actuator parameters. The core of the landing guidance strategy is the so-called quasi-optimal time algorithm, responsible for the terminal guidance and energy management exiting. This algorithm minimizes the difference between the time to go and the estimated duration of the terminal maneuvers to guarantee an accurate landing also in the presence of strong winds. This paper presents the guidance strategy and demonstrates the feasibility of the design by Monte Carlo analysis of the Space Rider landing using a six-degree-of-freedom parafoil–payload model. The design presented in this work successfully passed the Critical Design Review of the Space Rider guidance, navigation, and control subsystem in December 2019.