What were the main criteria used in the selection of the Apollo lunar landing sites?
Every landing site was selected, in part, to give us a different look at the lunar materials, and that included their composition. I guess one would say there were two major criteria in the selection of landing sites. One was the desire to sample as broad a range of rock and chemical types of lunar materials as we could, and, secondly, to look at as broad a range of processes, of structural features, geographic features, if you will, as we possibly could. And, indeed, the sharpest contrasts would have existed compositionally, in reference to your question, between those landings on the lunar maria-the dark parts of the Moon, the mare basalt areas-the highlands, such as in Descartes at the Appenine front, in the south and north massifs of later missions; and, of course, the landing at the Apollo 14 site, known as Frau Mauro, where we ran into this material I referred to earlier as KREEP. So, there were three major contrasting compositional regions sampled, and within even the individual
