Constant-Thrust Orbital Transfer About Binary Asteroids Using Bilinear Tangent Guidance

By applying the bilinear-tangent (BLT) guidance law, a near-optimal and computationally efficient BLT constant-thrust guidance (BCG) algorithm is introduced for orbital transfers about a binary asteroid system. This algorithm is accomplished by using the BLT guidance law combined with the Newton–Raphson predictor–corrector algorithm and manifold patching techniques. BCG can plan a variety of fuel efficient constant-thrust state/orbit to state/orbit transfers based on the types of the initial/target orbits and the selected maneuver types, including single-burn transfers and multiple-burn transfers leveraging manifolds. For the study case of 66391 Moshup, a 600-kg, BCG-guided spacecraft with a 24-mN thruster performed an aggressive noncoplanar transfer between L1 and L2 Halo orbits at the cost of only 3.38 g of fuel. Then, the BCG-guided trajectories’ robustness is validated thoroughly by N = 600 Monte Carlo simulations, respectively. Finally, BCG's excellent tradeoff between computational efficiency and near-optimality is well demonstrated by comparison with well-established optimization methods. For example, in a coplanar transfer with a 1.5-mN thruster, BCG can converge over 200 times faster than interior point optimization with only a 9% cost surplus in fuel compared to the optimum. It is indicated that the BCG algorithm is a promising option for autonomous orbital control in binary asteroid missions considering its computational and fuel efficiency.