Trajectories suitable for Apollo-type lunar missions must satisfy a large variety of constraints. This paper is concerned with two possible constraints for the return phase of the mission;namely, trajectories which (l) require entry ranges less than 5,000 nautical miles, and (2) permit landing within a 4-hour period following sunrise. The general characteristics of trajectories which satisfy these constraints are discussed, and those combinations of lunar launch time, orbital plane inclination, and landing site latitude which allow such trajectories are indicated.
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