¹Keelan T. O’Neill,¹Einar Fridjonsson,¹Declan Smeed,²Timothy Hopper,¹Michael Johns
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115544]
¹Department of Chemical Engineering, University of Western Australia, Crawley, WA 6009, Australia
²Orebody Intelligence, Orica, 37 Kewdale Rd, Welshpool, WA 6106, Australia
Copyright Elsevier

Water is critical in the future of space exploration and development of planetary bodies. Benchtop nuclear magnetic resonance (NMR) is a geophysical measurement technique with the potential to be used for identification and characterisation of water resources on planetary bodies, such as the Moon and Mars. In this work, we explore the potential of NMR for space exploration by conducting measurements on Lunar and Martian regolith simulants using two main NMR pulse sequences. The first sequence is a decay due to internal fields (DDIF) pulse sequence which probes the pore size of the porous structure created by the regolith simulants. We then use a simple pore-to-particle size model to estimate the particle size distribution of the simulants and validate this against laser particle size analysis (LPSA) data. The DDIF type sequence can also be used to resolve the material surface relaxivity: which is useful in understanding the concentration of paramagnetic species as well as for correlating the length scales of various water volumes. The second pulse sequence utilised is a multi-echo sequence used to quantify fluid volumes as well as total moisture content within the porous media. The fluid volumes observed include adsorbed or hydrated water bound to clay minerals, as well as interparticle water between the regolith simulant grains. The NMR measured moisture content showed reasonably good agreement to corresponding gravimetric measurements used for validation. Finally, we discuss the implications of the current measurements and provide suggested focal points for potential future developments of NMR systems for space exploration.

¹Lingzhi Sun,¹Paul G. Lucey
Earth and Planetary Science Letters (in Press) Link to Article [https://doi.org/10.1016/j.epsl.2023.118074]
¹Hawai‘i Institute of Geophysics and Planetology, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
Copyright Elsevier

Dunite is a rock type composed of more than 90% olivine, and Mg-rich dunite has been suggested to be a rock type that may represent upper mantle of the Moon. Dunite rocks might have been exposed on basin rings by basin-forming impacts. However, previous studies reported no unambiguous evidence of mantle dunite from lunar samples and remote sensing detections. In this work, we applied a mantle boulder candidate search algorithm around the Imbrium basin using radiative transfer modeling and datasets from Moon Mineralogy Mapper and Multiband Imager. We found two boulders consisting of ∼90 vol% olivine with 95 Mg# on Copernicus central peaks, which are possible mantle dunite excavated by Imbrium basin or Copernicus crater. We also found that non-dunite boulders on Copernicus central peak show a large variation in olivine content (8–51 vol%). We infer this is a result of the complicated process of Mg-suite formation in the lower crust or mechanical mixing during the Imbrium basin forming event. The algorithm we presented has a great potential to be applied to lunar basins for a global search for mantle candidate boulders.