To achieve the planetary safe landing,the ability of evaluating new landing sites,redesigning trajectory and maneuvering to a new and safe site must be ensured while hazards are detected in the nominal landing site.This paper investigates the hazard avoidance scheme employing the three-dimensional optimal zero-effect-miss/zero-effect-velocity feedback guidance algorithm for its robustness and easy to implement.Meanwhile,by introducing the bisection search method,with the auxiliary of the numerical results of the feedback guidance algorithm,the open-loop optimal time-to-go can be determined in real time,which reduces fuel consumption a lot.The accessibility and optimality evaluation of the candidate new landing sites,which acquired by applying the scheme,lay the foundation for selection of the new landing site.The performance of the scheme proposed is demonstrated through numerical simulation examples and Monte Carlo simulations,and the results indicate that the fuel-optimal redesigned trajectory can always be found.