We estimated the mineralogy of the effusive and explosive units at the Gardner shield volcano using Chandrayaan-1 Moon Mineralogy Mapper (M3) data and Lunar Reconnaissance Orbiter (LRO) Diviner data. We present a high-resolution 3D morphological map of the shield based on LRO Camera (LROC) Narrow Angle Camera (NAC) and Wide Angle Camera (WAC) images and LOLA SLDEM data. The shield shows evidence of caldera subsidence with downsag and possible trapdoor style subsidence, including a central normal fault, partially developed fault-ring structure, resurgence, and subsidence blocks, two sinuous rilles, graben, lineaments, a parasitic cone SE of the central caldera. The shield comprises 5 prominent voluminous and 10 thinner effusive basaltic flow units, and one explosive unit displaying pyroclastic material at the center of the caldera. North of the caldera is Gardner crater, which is a simple bowl-shaped impact crater, formed after the shield, revealing fresh mineralogy from the shield and highlands, including high calcium pyroxene, olivine, and Fe-spinel. The crater has a dark debris flow on its eastern wall, landslides, a boulder cluster, boulder tracs, and lineaments. The shield presents a unique lava river channel originating from a secondary oblique fault ~ 5 km wide and spreading tens of kilometers at the northern part of Mare Tranquillitatis. Our volcano-tectonic study indicates that the Gardner shield is a science rich site with exploration potential to study basaltic caldera-forming volcanoes with in-situ pyroclastic resources as it comprises almost all the major compositional and structural aspects to understand lunar thermal, tectonic, and geological evolution.

NASA designated Reiner Gamma (RG) as the landing site for the first Payloads and Research Investigations on the Surface of the Moon (PRISM) delivery (dubbed PRISM-1a). Reiner Gamma is home to a magnetic anomaly, a region of magnetized crustal rocks. The RG magnetic anomaly is co-located with the type example of a class of irregular high-reflectance markings known as lunar swirls. RG is an ideal location to study how local magnetic fields change the interaction of an airless body with the solar wind, producing stand-off regions that are described as mini-magnetospheres. The Lunar Vertex mission, selected by NASA for PRISM-1a, has the following major goals: 1) Investigate the origin of lunar magnetic anomalies; 2) Determine the structure of the mini-magnetosphere that forms over the RG magnetic anomaly; 3) Investigate the origin of lunar swirls; and 4) Evaluate the importance of micrometeoroid bombardment vs. ion/electron exposure in the space weathering of silicate regolith. The mission goals will be accomplished by the following payload elements. The lander suite includes: The Vertex Camera Array (VCA), a set of fixed-mounted cameras. VCA images will be used to (a) survey landing site geology, and (b) perform photometric modeling to yield information on regolith characteristics. The Vector Magnetometer-Lander (VML) is a fluxgate magnetometer. VML will operate during descent and once on the surface to measure the in-situ magnetic field. Sophisticated gradiometry allows for separation of the natural field from that of the lander. The Magnetic Anomaly Plasma Spectrometer (MAPS) is a plasma analyzer that measures the energy, flux, and direction of ions and electrons. The lander will deploy a rover that conducts a traverse reaching ≥500 m distance, obtaining spatially distributed measurements at locations outside the zone disturbed by the lander rocket exhaust. The rover will carry two instruments: The Vector Magnetometer-Rover (VMR) is an array of miniature COTS magnetometers to measure the surface field. The Rover Multispectral Microscope (RMM) will collect images in the wavelength range ~0.34–1.0 um. RMM will reveal the composition, texture, and particle-size distribution of the regolith.