Robinson, Mark - Discoveries from the Lunar Reconnaissance Orbiter and Future Human Exploration of the Moon

Abstract: 
Measurements from the Lunar Reconnaissance Orbiter (LRO) are providing answers to old questions, calling into question currently held beliefs, and raising new questions both in terms of science and exploration. Globally distributed meter-scale LROC images revealed a large population of young compressional scarps that were likely formed as molten portions of the core transitioned to solid, resulting in a negative volume change that put the brittle crust into a compressional state. These features are so young that is likely, if not certain, that large moonquake driven surface deformation occurs in the present era. Rather than clarifying the relative ages of late Copernican craters, LROC images call into question the relative significance of primary, secondary, and auto-secondary impacts and the effect of target strength (impact melt rocks, granular ejecta) on the cratering record. LROC images revealed over 75 occurrences of small (<5 km) young volcanic extrusions with ages proposed to be <200 my. Analysis of observations from LROC and Diviner revealed a previously unknown farside silicic volcanic center between Compton and Belkovich craters, far from any previously known domes or red spots. The age of this center is difficult to determine with accuracy due to its size and probable resurfacing events (pyroclastic?).  Similar observations of the Lassell massif also raise the possibility of silicic explosive activity. Like its farside counterpart the age of terminal volcanic activity at Lassell is ambiguous. LROC observations led workers to question the current stratigraphic relations of touchstone basin-forming events (Imbrium, Serenitatis, Crisium), and thus the body of evidence for the late heavy bombardment. Observations with nearly every instrument onboard LRO show the poles to more enigmatic than previously thought. For the same crater some measurements indicate significant H deposits while others show no enrichment. Likely this conundrum is the result of depth sensitivity of the various measurements and a complex movement of volatile species within the regolith. 
Preparing for a human return to the Moon requires an exploration strategy to investigate key resource, engineering, and science questions. Precursor missions include polar landers with mobility to investigate distribution of volatiles. Simple yet capable long-lived rovers to measure, sample, and scout major geologic terrains. Sample return is required to test current hypotheses and calibrate the relative cratering record. These robotic missions feed into the decision process for selecting crewed targets, deliver samples to human exploration sites, and test technologies for missions to Mars. Early crewed missions will provide the means to unravel complicated geologic problems (i.e. complex silicic volcanism), test and implement resource utilization strategies, and provide the experience base to live and work on another planet. An exploration strategy of this scale is best carried out through close international cooperation implementing a sustainable plan robust to political winds.