Spacecraft rendezvous with constant thrust

Spacecraft rendezvous is a crucial aspect of space exploration and satellite servicing; hence, it is one of the most widely-studied problems in astronautics. The first spacecraft rendezvous missions date back to the dawn of the space age. In this paper, we focus on the problem of spacecraft rendezvous using constant-magnitude thrust, because, this setup is more realistic for small spacecraft operating electric propulsion systems. Considering the fact that the only optimal solutions for the general constant-magnitude-Thrust rendezvous reported in the literature were found by means of direct optimization, we propose a simple state transformation, which leads to new solutions for rendezvous with constant-magnitude thrust. First, we show that by expressing the rendezvous dynamics as a driftless dynamical system, the solution of the TPBVP emanating from the minimum-Time rendezvous problem becomes simpler; second, the same driftless form can be used to synthesize a feedback rendezvous law considering the constant thrust-magnitude constraint.