Spacecraft techniques for lunar research.

The most significant findings about the Moon obtained by spacecraft so far, have resulted from measurements of gravity, electromagnetic properties, seismicity, mechanical properties, geologic features, composition, ages, and the lunar environment. A number of major lunar questions remain to be answered. Other properties, measurable with spacecraft, which may provide data critical to answering these questions include geometrical shape, motions, and heat flow. In this paper specific measurements that should provide critical data for each of these questions are identified, with some candidate techniques. Among the suggested techniques that have not yet been used are very long baseline interferometry (Earth-Moon baseline), gravity gradiometry, elemental analysis by neutron interactions, and remotely-controlled on-moon microscopy.