Ray, SoumyaArevalo, Ricardo Jr.Southard, AdrianWillhite, LoriBardyn, AnaisNi, ZiqinDanell, RyanGrubisic, AndrejGundersen, CynthiaLlano, JulieYu, AnthonyFahey, MollyHernandez, EmanuelGraham, JacobLee, JaneErsahin, AkifBriois, ChristelleThirkell, LaurentColin, FabriceMakarov, AlexanderRationale Characterization of Regolith And Trace Economic Resources (CRATER), an Orbitrap™-based laser desorption mass spectrometry instrument designed to conduct high-precision, spatially resolved analyses of planetary materials, is capable of answering outstanding science questions about the Moon's formation and the subsequent processes that have modified its (sub)surface. Methods Here, we describe the baseline design of the CRATER flight model, which requires <20 000 cm3 volume, <10 kg mass, and <60 W peak power. The analytical capabilities and performance metrics of a prototype that meets the full functionality of the flight model are demonstrated. Results The instrument comprises a high-power, solid-state, pulsed ultraviolet (213 nm) laser source to ablate the surface of the lunar sample, a custom ion optical interface to accelerate and collimate the ions produced at the ablation site, and an Orbitrap mass analyzer capable of discriminating competing isobars via ultrahigh mass resolution and high mass accuracy. The CRATER instrument can measure elemental and isotopic abundances and characterize the organic content of lunar surface samples, as well as identify economically valuable resources for future exploration. Conclusion An engineering test unit of the flight model is currently in development to serve as a pathfinder for near-term mission opportunities.en-USArticle