Strong reasons exist to hypothesize that phyllosilicates, that is, clay minerals, played a critical catalytic role in the organic synthesis of prebiotic and possibly early biotic compounds and structures. Phyllosilicates would be expected to be abundant at the surface of early Earth (the Hadean) by the hydrous alteration of impact-generated silicate debris. The explorations of Earth, the Moon, and Mars permit reasonable inferences about physical conditions on prebiotic Earth. Also, currently available information allows the definition of necessary steps in prebiotic synthesis in which phyllosilicates may have participated. Consideration of these steps supports the plausibility that such minerals provided catalytic, substrate, and organizational functions for prebiotic and possibly early biotic development of organic structures, leading to formation and replication of ribonucleic acid (RNA) and, in turn, leading to a prebiotic RNA world. Ultimately, prokaryote cells may owe some of their functions to the inherent characteristics of associated phyllosilicates.

Future lunar exploration will provide opportunities to expand the human scientific exploration of the Moon and, eventually, Mars. Planning for renewed field exploration of the Moon entails the selection, training, and capabilities of explorers; selection of landing sites; and adoption of an operational approach to extravehicular activity. Apollo program geological exploration, and subsequent analysis and interpretation of findings and collected samples underpin our current understanding of lunar origin and history. That understanding continues to provide new and important insights into the early histories of Earth and other bodies in the solar system, particularly during the period when life formed and began to evolve on Earth and possibly on Mars. Specific new lunar exploration objectives include: (1) testing the consensus “giant impact” hypothesis for the origin of the Moon; (2) testing the consensus impact “cataclysm” hypothesis; (3) determining the temporal flux of large impacts in the inner solar system; and (4) investigating the internal structure of the Moon. Apollo samples also identified significant and potentially commercial lunar resources that could help satisfy future demand for both terrestrial energy alternatives and space consumables. Equipment necessary for successful exploration includes that required for sampling, sample documentation and preservation, communications, mobility, and position knowledge. Easily used active geophysical, portable geochemical, and in situ petrographic equipment can greatly enhance the scientific and operational returns of extended exploration compared to that possible during the Apollo program.

Field geological research, as traditionally practiced on Earth, is an extremely flexible science. Although field geologists plan their traverses ahead of time—nowadays with the advantage of remote-sensing data—initial plans are continually modified in response to observations, such that traverses evolve over time. This research modality differs from that utilized in extreme environments on Earth (e.g., on the ocean floor), on the Martian surface by the mobile laboratories Spirit and Opportunity , and by the Apollo astronauts during their explorations of the Moon. Harsh and alien conditions, time constraints, and resource limitations have led to the development of operational modes that provide a constrained and usually lower science return than traditional field geology. However, emerging plans for renewed human exploration of the Moon, Mars, and near-Earth asteroids serve as an opportunity to invent a new paradigm for advanced planetary field geology that embraces coordinated human and robotic research activities. This approach will introduce an operational flexibility that is more like that of traditional field geology on Earth. In addition, human and robotic collaborations, combined with the integration of new “smart” tools, should provide an augmented reality that leads to even greater science return than traditional field geology. In order to take full advantage of these opportunities when planetary field geology again becomes practical, it is imperative for field geologists on Earth to begin right now to learn how best to incorporate advanced technologies into their research. Geologic studies of analog sites on Earth that employ new technology-enabled strategies rather than traditional research methods provide ideal opportunities to test and refine emerging designs for advanced planetary field geologic studies, as well as to gain new insights into terrestrial geologic processes. These operational experiments will be most informative if they embrace the entire geologic research process—including problem definition, field observation, and laboratory analysis—and not simply field work. The results of such comprehensive research can be used to inform the design of a maximally effective training regimen for future astronaut explorers.