The existence of lunar water has been confirmed through a variety of remote sensing data, but to date, ground truth remains to be provided. Extended in-situ measurements will allow determining the form and abundance of lunar water and thereby gaining knowledge about its origin, formation, stability, and mobility. Forms of water may vary from loosely adsorbed and highly volatile hydroxyl groups, to water molecules, to thick subsurface deposits of crystalline ice (e.g., Li et al., 2018, and references therein). Possible sources of lunar water are asteroid or comet impacts, surface interactions with the solar wind, and outgassing from the lunar interior (e.g., Anand, 2010;Lucey, 2009;Lucey et al., 2020). It is unclear however, how larger ice deposits can develop from such surface-related processes (Cannon & Britt, 2020). Vertical transport of lunar water down to several meters can occur by impact mixing of the surface regolith. But because this is a highly energetic process, it is likely that released volatile material will be lost by sublimation and can only accumulate via trapping on a colder regolith surface. Subsurface migration therefore mainly happens by diffusion of molecules along particle surfaces or in voids between particles. Molecules trapped at the surface may diffuse to deeper layers of regolith by a mechanism called ice pumping, caused by thermal gradients and

Understanding how the surfaces of airless planetary bodies—such as the Moon—scatter visible light enables constraints to be placed on their surface properties and top boundary layer inputs to be set within thermal models. Remote sensing instruments—such as Diviner onboard the Lunar Reconnaissance Orbiter—measure thermal emission and visible light scattering functions across visible (∼0.38–0.7 µm) to thermal infrared (TIR) wavelengths (∼0.7–350 μm). To provide ground support measurements for such instruments, the Oxford Space Environment Goniometer (OSEG) was built. Initially, the OSEG focused on measuring TIR directional emissivity functions for regolith and regolith simulant samples in a simulated space environment, but it has recently been modified to measure visible wavelength Bidirectional Reflectance Distribution Functions (BRDFs) of samples in ambient conditions. Laboratory-measured BRDFs can be used (1) to test and to help interpret models—such as the Hapke photometric model—and (2) as visible scattering function inputs for thermal models. This paper describes the modifications to and initial calibration measurements taken by the Visible Oxford Space Environment Goniometer with a 532 nm laser, and details how this setup can be used to measure BRDFs of regolith and regolith simulant samples of airless planetary bodies.

Selected in 2019 as a NASA SIMPLEx mission, Lunar Trailblazer is in implementation for flight system delivery at the end of 2022. The mission's goal is to understand the form, abundance, and distribution of water on the Moon and the lunar water cycle. Lunar Trailblazer also collects data of candidate landing sites to inform planning for future human and robotic exploration of the Moon and evaluate the potential for in situ resource utilization. Lunar Trailblazer's two science instruments, the High-resolution Volatiles and Minerals Moon Mapper (HVM 3 ) and the Lunar Thermal Mapper (LTM) provide simultaneous high-resolution spectral imaging data to map OH/water, crustal composition, and thermophysical properties from a 100±30 km lunar polar orbit. The ~210-kg flight system deploys from an ESPA Grande and utilizes a ~1000 m/s ΔV hydrazine chemical propulsion system, similar to that employed by GRAIL. Trailblazing elements include the novel state-of-the-art dataset collected at substantially reduced price point, fully geographically co-registered data products delivered to the Planetary Data System, planetary mission team demographics, Caltech campus mission operations, and student staffing of select mission ops roles. Lunar Trailblazer's pioneering development is providing key lessons learned for future planetary small spacecraft.TABLE OF CONTENTS 1. INTRODUCTION .

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<p>The evaluation of candidate landing sites for a solar powered ice drilling mission for the Moon was done at the southern polar region. Selection criteria were low slope angle surface, occasionally solar illuminated location with direct Earth radio access, together with <125 K temperature at 1 m depth. The survey showed thee-four areas where all of these needs were satisfied at sites close to each other (see the Figuew 1 below). Considering these regions, the maximal diameter for safe and scientifically relevant landing ellipse sizes are around 0.5-1 km diameter, while containing <20% of unfavourable locations can be larger around 2-4 km. The best location is around -27.03 W -86.75 S, where solar illumination can have 30% of time at least and WEH values are elevated. </p> <p> </p> <p><img src="" alt="" /></p> <p>Figure 1. Insets of magnified versions of the four candidate areas.</p>