Orbital Motion Under Continuous Normal Thrust

S PACE is becoming increasingly congested, contested, and competitive [1]. The need to explore a new way of space maneuvering is urgent. A detailed study of orbital motion of spacecraft under continuous radial thrust [2–4], tangential thrust [5–7], and other special types of thrust can be found in the previous studies, and several interesting conclusions have been obtained. However, to the best of our knowledge, orbital motion resulting from continuous normal thrust has been studied infrequently. In this Note, the problem of continuous normal thrust acceleration being applied to vehicles in both a Keplerian circular orbit and an elliptical orbit is investigated and some interesting results are obtained. Using a quaternion-based formulation, the problem in the circular orbit case can be solved analytically, which is not true of the elliptical orbit case. Therefore, Floquet theory is employed to determine the orbitalmotion characteristics in the elliptical case. The results indicate that the orbital motion of spacecraft under continuous constant normal thrust acceleration departing from a circular orbit presents a displaced orbit, whereas in the elliptical case, the orbital motion exhibits a quasi-periodic orbit with upper and lower circular boundaries, the radii of which can be determined using the integral constants.