Orbit Keeping about the Martian Moons with a Robust Path Following Control

Author(s)

Negri, Rodolfo Batista ; Prado, Antonio F. B. de A. ; IEEE

• Document type: Journal article
• Source: 2021 EUROPEAN CONTROL CONFERENCE (ECC); v. N/A, p. 6-pg., 2021-01-01.

Abstract

In the last years, a considerable number of missions were proposed to study the Martian moons Phobos and Deimos. These satellites are known to have a highly perturbed environment, due to high-order terms of the moons' gravity fields, and mainly to non-negligible third-body effects from Mars. This work intends to address an important part of missions to such bodies that is the orbital maintenance. A feedback control for orbit keeping can decrease the mission operational cost, make the spacecraft readily respond to changes in the environment and increase theu science outcome by allowing different orbital configurations and a more audacious operation. However, under a practical perspective, this is not a trivial task, as this orbit keeping law should be robust, accommodate idle-thrusters periods, and applicable to any orbital configuration. In order to accomplish these goals, we apply a robust path following control law recently proposed in the literature. This control law is derived under the frame of the sliding mode control theory, with a novel set of sliding surfaces specially designed for the problem, to robustly cope with bounded unknown disturbances. Because it is a path following law, the spacecraft can safely accommodate long term idle-thrusters periods, allowing it to make scientific measurements with no thrust interference and to reduce the fuel expenditure. We prove the efficacy of our path following law for different orbital configurations about Phobos and Deimos, considering a restricted three-body problem composed of the moon, Mars and the spacecraft. We also consider a polyhedron model to simulate higher order terms of the moons' gravity field. Our results indicate that the proposed autonomous orbit keeping is a reliable and efficient tool for Deimos exploration. In the case of Phobos, because of the large deviation from a perturbed Keplerian orbit due to third-body effects, a relative large amount of fuel is expected to be necessary to maintain a Keplerian orbit, which makes the proposed control law more attractive only to highly demanding tasks. (AU)

• FAPESP's process: 17/20794-2 - Study of dynamics, guidance and control applied to asteroid deflection
• Grantee: Rodolfo Batista Negri
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 15/19880-6 - Aster project: analysis of the mission to the triple asteroid
• Grantee: Antônio Fernando Bertachini de Almeida Prado
• Support Opportunities: Research Grants - Visiting Researcher Grant - International
• FAPESP's process: 16/24561-0 - On the relevance of small bodies in orbital dynamics
• Grantee: Othon Cabo Winter
• Support Opportunities: Research Projects - Thematic Grants