Abstract: Current research on trajectory optimization of deep space mission hardly takes launch constraints into consideration, thus resulting in low efficiency in ballistic-orbit splicing design. A calculation model of ballistic-orbit splicing is established considering launch vehicle’s launch azimuth and coasting time constraints. The calculation formula of launch vehicle’s launching azimuth and coasting time under an arbitrary deep space departure speed is obtained with zero gravitational perturbation assumption. Through this model, the variation pattern of splicing solution set under different deep space departure speed, launch site geographical position, rocket’s launching azimuth and coasting time constraints is analyzed. The  δ-C3  map method is proposed to represent the feasible range of deep space launch capability of specified launch vehicle. Combined with Pork-Chop map, this method can be easily used to determine whether one type of launch vehicle is suitable for specific deep space launch mission. According to this method, the design specifications on launching azimuth and coasting time of China’s future launch vehicles suitable for deep space missions are proposed. 

Key words: Deep space exploration, Ballistic orbit splicing, Launch vehicle, Launching azimuth, Coasting time