For the lunar return mission, a concern of the entry guidance requirement is the full flight envelope applicability and landing accuracy control. A concise numeric predictor-corrector (NPC) entry guidance (NPCEG) algorithm is developed for this requirement. It plans a real-time trajectory on-line by modulating the linear parameterized bank profile. To meet the path constraint, we propose an integrated guidance strategy which combines NPC method with an analytical constant drag acceleration method. Monte Carlo analysis shows that the algorithm is sufficiently robust to allow precision landing with a delivery error of less than 2.0 km for the entire between 2,500 km and 10,000 km range.
