Robust orbit control for proximity operations around asteroids

Abstract

Proximity operations around asteroids are currently at the forefront of space research and industry due to their strategic and scientific relevance. As recent missions increasingly rely on autonomous systems to reduce operational costs, maintaining low-altitude orbits around asteroids without support from the ground represents a key challenge in enabling the transition to a fully autonomous mission architecture.

This research proposes a sliding mode control framework to ensure robustness against navigation uncertainties and gravitational perturbations while accommodating the on/off operating mode of conventional monopropellant thrusters. The designed station-keeping scheme was tested for a range of orbits with varying sizes and orientations around asteroid Eros, demonstrating that the spacecraft can reach altitudes as low as 2 km by relying exclusively on the knowledge of the asteroid’s gravitational parameter. A line-of-sight tracking mode, replacing the conventional two-satellite formation control approach, reduces station-keeping costs and increases coasting time, allowing more opportunities for scientific operations.