ORBITAL MISSION ANALYSIS FOR A LUNAR MAPPING SATELLITE
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Using a frozen orbit concept, we establish a family of lunar mapping orbits which are near circular, near polar, near constant low altitude, and near Sun-synchronous. Orbits are sought whose mean elements are constant, except for uniform precession of the line of nodes and periapsis over a month, and periodic element variations are suitably small. Of special significance, it is desired that these frozen orbits be weakly perturbed due to uncertainty in the zonal harmonics. With the LGM0281 recent lunar gravity model, we find a family of frozen orbits that are near polar, so global coverage can be achieved in one month. This family of frozen orbits yields an attractive set of lunar mapping orbits with 100 km altitude and good control over sunlight conditions. We evaluate the stability of these orbits to uncertainty in the gravity model through simulation using several gravity models.