Drag augmentation sails for space vehicle de-orbit

The uncontrolled growth of orbital pollution and the threat that it poses to space operation demand for appropriate mitigation measures. End-of-life deorbiting is the most considered solution to prevent additional debris generation in LEO. Among the several means of performing this manoeuvre, drag-sail assisted decay is one of the most studied. The low mass of deorbit sail systems makes them an extremely attractive technology. In this thesis the capabilities and properties of drag-sails are extensively investigated. An orbital propagation model using a NRLMSISE-00 atmosphere and zonal harmonics gravity is used to analyze the influence of initial orbit and solar cycle dependent atmosphere on the deorbiting process. Increasing the fidelity of the analysis, a 6 degrees-of-freedom discrete surface elements model of sail and spacecraft is built, including self-shielding and interbody shielding effects for both aerodynamic and solar radiation pressure emulation. These algorithms, integrated in the orbital propagator, are employed to study the passive attitude stability properties of several sail geometries. Parameters such as sail shape, size and distance to the spacecraft (mast length) are individually tested to better understand its influence on the deorbit performance. Additionally, the sail optical characteristics are examined due to their strong impact on the solar force contribution. Furthermore, the correlation between the solar radiation pressure force and the passive stability of the deorbiting system is demonstrated. As further evidence of the drag-sail feasibility, two realistic test case solutions are designed and supported by the correspondent mass budget. The outcome of this thesis extensively demonstrates the capabilities of the designed deorbiting system, while providing a preliminary overview of the main critical aspects. Within this work drag-sail are shown to be a high potential solution for the space debris problem, allowing considerable mass saving and passive deorbiting.