Systems Engineering for Asteroid Exploration GNC Validation Test

In the last decades, a growing number of scientists and engineers have been interested in the topic of asteroid exploration. Several spacecraft have been launched on scientific missions, and more are likely to follow. Given the great distance between Earth and the asteroid, the spacecraft must be managed independently. However, it is difficult to accomplish this type of mission because of the limited previous knowledge available about the target, the complicated dynamics environment, and the considerable time delay. The increasing complexity highlights the necessity of developing techniques and instruments that enhance the system process's design, verification, and validation. The goals that must be sought are cost and effectiveness reduction without sacrificing trust in the finished result. Within the System Engineering context, this work aims to create a method to verify and validate these requirements for the GNC system during the asteroid rendezvous and Touch-And-Go operations. Model Based System Engineering (MBSE) relies on the concept that feasibility, capabilities, and system performances may all be independently verified at any time via simulation tests and in accordance with the system's life cycle phase. The research activity, in which this thesis is inserted, focuses on defining a methodology to support the test for autonomous GNC systems design and validate the proposed model under nearly realistic conditions. The objective of the project is to investigate the use of SysML to digitalize the GNC description. In particular, in support of improving the effectiveness of the design and verification of a space subsystem. The project purpose is an iterative process to apply throughout the entire system life cycle. The method results in a perfectly balanced system, thoroughly specified and well-documented. The thesis studies the methodology to understand and apply SysML to model systems as part of a model-based system engineering approach. The work is organized into four parts: the first one contains the introduction, which provides a context and overview of system engineering, a summary of the research objectives, and the state-of-art of the use of MBSE applied to space systems. The second part provides a detailed description of the case study examined for this thesis. Chapter 2 contains the requirements the system shall verify and a comprehensive analysis. The third chapter focuses on the mathematical formulation of the design of an autonomous GNC algorithm, which aims to meet the main requirement of the mission, to autonomously insert the spacecraft in the trajectory around with an injection error that ensures no collisions while consuming the least amount of fuel possible. The third part is the core of this thesis, addressing the functional analysis in Chapter 4, identifying the essential functions the system must perform, transitioning to the design of the model with an MBSE approach with SysML, using the modeling tool CATIA No Magic Cameo Systems Modeler. In Chapter 5, the system architecture of the GNC system is detailed. The aim is to address the need for a fully autonomous system and verify the requirements to design an efficient performance system. The final part describes the process and strategies that could be followed for the testing phase. Furthermore, in order to test the algorithm in a real-world operational setting, it is crucial to carry out the Guidance, Navigation, and Control verification and validation (V&V) procedures using hardware-in-the-loop testing.