Abstract: The non-Keplerian displaced orbits by low-thrust propulsion have significant applications in observation missions of the deep space and Earth polar region. The development of the continuous low-thrust propulsion technology represented by the electric propulsion and solar sail propulsion was detailed. The heliocentric and planetary displaced orbits were discussed to reveal the nonlinear dynamical characteristics, stability and orbit keeping strategies. The advantages of artificial Lagrangian points generated in the three-body problem were analyzed as well as its application in deep space explorations. Moreover, the relative dynamics and control of formation flying in displaced orbits were discussed. Finally, new research directions and applications were proposed for the research challenges of displaced orbits by low-thrust propulsion.

Key words: continuous low-thrust propulsion, non-Keplerian displaced orbit, solar sail, artificial Lagrangian points, displaced formation flying