Design and analysis of direct abort trajectory for a crewed lunar mission based on the quasi-lambert problem

A direct design method for direct abort trajectory based on the quasi-lambert problem is proposed. The re-entry constraint is analytically addressed via a quasi-lambert problem instead of variables iteration and optimization method in the past. Then a new parameter is introduced to determine the plane. The exact solution is determined by differential correction based on the initial solution. Numerical simulation is carried out to test the validity and efficiency of the method. The comparison with STK verifies its reliability. Additionally, the characteristics of direct abort trajectory and their application in the option strategy for different abort ways are studied. The flight time and abort point affect the abort trajectories' velocity increment and the latitude of the landing area.