We already know something about it and so have a clearer idea of what to look for  In many ways our trips to the moon so far tell us which questions we need to ask, the next stage is to find the answers. It also has the advantage of being close enough to earth that samples and data can be relatively easily sent between the two.  The moon functions as a sort of attic for the Earth, a repository of rocks than are no longer found on earth. There are also resources, such as lunar glass and Helium3, which could be potentially very valuable if they are there in sufficient quantities, human beings can simply cover more territory than Robots and make assessments like these more easily. If these rare minerals exist in sufficient quantity they could potentially fund the whole project [i] .  [i] "Why Go Back to the Moon?" NASA. January 14, 2008