Trajectory design analysis of transport operations of an electrically propelled space tug during transfers to geostationary orbit, orbit around the moon and to libration points in the Earth - Moon system

A trajectory design analysis has been conducted for transfers of an electrically propelled space tug with a solar power system from low-Earth orbit to geostationary orbit, low lunar orbits, and to libration points with return to the parking orbit. The analyses were done for a range of the tug design parameters, which were selected by varying exhaust velocities (specific impulse) of the propellant. Taken into account was the fact that the thrust efficiency of actual engines varies according to the operational mode and usually increases with an increase in the exhaust velocity. Two options for the solar power generating system were considered: one based on existing photovoltaic converters having a 28% efficiency; and the other based on advanced photovoltaic converters having an up to 40% efficiency. The analysis has demonstrated the feasibility in principle of efficient use for transportation operations in the Earth - Moon system of an electrically-propelled tug with an about 400 kW solar power-generating system.