Further Advances for staging orbits of manned lunar exploration mission

With the increasing demand for manned lunar exploration and deep-space exploration missions, the application value of the three-body orbit in cislunar space becomes increasingly prominent due to its special orbital char- acteristic. The efficient round-trip versions for manned missions of both the nominal fuel-optimal and emergency transfers between NRHO and the Moon are exploited deeply. The collocation method and indirect optimization technique with constraint gradients are utilized in conjunction with the features of the NRHO configuration to increase the algorithm's accuracy and speed. The required initial value and suitable collocation point can be determined quickly based on a global search strategy and Lambert algorithm. To highlight the effectivity of the design scheme and aim at global lunar surface exploration, typical scenarios of lunar sites at different latitudes and longitudes are investigated with various time of flight, which show that the difference of fuel consumption varies from a few kilograms to hundreds of kilograms. Meanwhile, the relations among Moon landing sites, transition time and fuel consumption are analyzed and the advantages and disadvantages of NRHO in lunar exploration are compared. The design results have some reference value for the lunar landing vehicle's deployment in the near-Moon space, as well as the round-trip transfer mission and key parameter selection.