CALCULATION OF SUBOPTIMAL HIGH-ELLIPTICAL ORBIT TO GEOSTATIONARY ORBIT TRAMSFERS FOR SPACECRAFT WITH LOW THRUSTERS

Abstract

At present the geostationary orbit is where communication satellites are preferably placed. Conventional orbital insertion profiles using chemical propulsion are insufficiently effective and require the use of heavy launch vehicles. Combining electric thrusters with chemical propulsion increases the mass of payload. On the other hand, orbital injection of a spacecraft using electrical propulsion brings up the problem of looking for an optimal control law. The paper discusses the transfer of a spacecraft with low-thrust electrical thruster from a high elliptical orbit to geostationary orbit. It proposes a suboptimal control law for the thrust vector. It provides examples of simulations of the transfer using the control law for various initial conditions. Parameters of intermediate high-elliptical orbits were selected to minimize the time of transfer to the final orbit, and estimates were made of the effects of the residual atmospheric drag during flight in the vicinity of the perigee of the orbit. Considering the low level of error, simplicity and high computational speed the proposed method can be used for trajectory design calculations. Key words: Suboptimal control law, local optimization theory, electric thruster, high-elliptical orbit, geostationary orbit, math model of controlled motion, Pontryagin's maximum principle.