A study of the landing phase of the Juventas CubeSat on the moon of the binary asteroid system Didymos

Asteroids present a threatening danger for humans. In the past, many have crashed on Earth, causing damage to structures and injuring people, including being a possible cause of extinction of the dinosaurs. Their exploration is also motivated by a great scientific interest; considered as the building blocks of our Solar System, exploring them should allow scientists to better understand its evolution and formation. They also present a great astrodynamic challenge due to their complex low-gravity dynamics. The Master Thesis discusses design solutions for the ballistic landing and bouncing of a nanosatellite on the moon of a binary asteroid system, identifies the crucial design parameters of a direct landing strategy and analyses the sensitivity to the parameters of a binary asteroid system. The proposed framework is generic and can be applied to the landing of a spacecraft on any binary asteroid system. The work is focused on the Juventas CubeSat, a nanosatellite taking part in the Asteroid Impact & Deflection Assessment (AIDA) collaboration, jointly led by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). The mission, set to start in 2022, will assess the possibility of deflecting asteroids using a kinetic impactor on the smaller of the two bodies and increase our knowledge of the Solar System. The chosen target for the mission is the Didymos binary asteroid system. The binary system is modeled using the Circular-Restricted Three Body Problem, further completed by adding gravity perturbations as well as solar radiation pressure. The interaction of Juventas with the surface of the moon is also modeled. The landing phase analysis aims at proposing reliable direct landing trajectories and bouncing on the moon of the binary system, characterized by a high success rate and a low settling time. The solutions found are presented and their characteristics are discussed through a Monte Carlo analysis, allowing to take into account uncertainties related to the mission. A sensitivity analysis of the trajectories to the parameters of Didymos is also performed, discussing the robustness of the solutions found. The key deliverable of this works are: provide a propagator allowing to simulate the motion of a nanosatellite in the Didymos system and additional numerical tools allowing to study and optimize landing trajectories, identify the set of parameters leading to a successful landing and low settling time and finally, propose a set of robust landing trajectories for Juventas.