Autonomous Maneuver Targeting Around Small Bodies Using Continuous-Thrust Propulsion

This paper presents a novel fuel-efficient continuous-thrust maneuver targeting (CTMT) algorithm that is capable of planning finite, continuous maneuvers in a larger autonomous spacecraft guidance architecture. This is accomplished using a constant-thrust bilinear tangent guidance law in conjunction with an optimal Lambert algorithm and a Newton-Raphson predictor-corrector targeting scheme. This simple approach is capable of planning a plethora of different free-time and fixed-time single-burn, burn-coast intercept, or burn-coast-burn bilinear tangent maneuvers from an initial state/orbit to a desired state/orbit. For the study case of asteroid Bennu, when used with thrust levels that are greater than 5% of the surface acceleration of asteroid Bennu, the CTMT algorithm is able to converge on 99% of orbital transfers initiated from a circular, 1.5 km, terminator orbit. Furthermore, many of the continuous-thrust maneuvers calculated by the CTMT algorithm are the optimal constant-thrust trajectories between two states in the small-body dynamical environment, and they are able to be calculated hundreds of times faster with the CTMT algorithm than with state-of-the-art nonlinear optimization algorithms. Ultimately, the CTMT algorithm shows promise as a candidate for future autonomous guidance applications.