C19


Model for Touchdown Dynamics of a Lander on the Solar Power Sail Mission

Roger Gutierrez RamonARalf BodenAJun'ichiro KawaguchiAOsamu Mori


The JAXA Solar Power Sail mission, bound to explore the Jupiter trojans, will face many challenges during its journey, and the landing manoeuvre is one of the most critical part of any space mission that plans to investigate the surface of celestial bodies. Asteroids are mostly unknown bodies and in order to plan a successful landing on their surface, a great number of landing scenarios need to be taken into account. For the future mission to the Jupiter trojans, a study of the landing dynamics and their effects on the lander has to be done. In order to do that, we created a simple model of a lander based on a possible design for the JAXA Solar Power Sail mission, and we simulated the possible landing scenarios. For this case, we only took into account the last part of the landing, which will be a free-fall. The lander is modelled as a rigid structure with a landing gear composed of four legs. We modelled the surface as a flat plane with different inclinations and we implemented the possibility of including small obstacles or rugosity. In the model, the lander is allowed 6 degrees of freedom. We tested sev  al landing possibilities with residual velocities and deviations in the starting point, and we evaluated the stability of the lander respect to its geometry. We have also considered damping strategies to protect the instruments and reduce the impact, allowing for a safer landing. The effect of including crushable honeycomb dampers in the legs is also implemented, simulated and evaluated, by using crushable honeycombs with different characteristics. We propose a good trade-off combination of the characteristics of the honeycomb that meets the requirements posed by the previous studies done on the lander for the Solar Power Sail mission to the Jupiter trojans. In addition, we included in the model the position, direction and characteristics of the thrusters. Thus, it could be used to study other phases of the landing sequence where active control of the lander is needed, and evaluate the behaviour and response of different control-loops algorithms for attitude and position control of the lander.