Microimaging Spectroscopy for the Exploration of Small Bodies: First Laboratory Measurements of Carbonaceous Chondrite and Hed Meteorites and a Proposed M6 Instrument for in Situ Measurement

Introduction: Analysis of mineralogy in geological samples typically requires the preparation of thin sections or preparation of powders for determination of crystal structure of chemical composition. Here we describe a new technique for petrology, i.e., simultaneous analysis of small-scale mineralogy and texture, using visible/shortwave infrared (VSWIR) imaging spectroscopy, that requires no sample preparation and can be performed on a rough or cut surface. This approach is ideal for the survey of a collection of rare or precious samples to best target locations for followup destructive analyses or for in situ exploration of planetary surfaces, when multi-step sample preparation procedures may be prohibitively complex. Herein, we describe first results from analyses of meteorites (carbonaceous chondrites and HEDs) as well as an implementation of our microimaging spectroscopy instrument that is proposed for the Discovery-class mission MERLIN [1] to investigate the moons of Mars by landing and conducting in situ elemental and mineral abundance measurements on Phobos, a D-class small body. Development History and Laboratory Instrument Specifications: Investments in imaging spectrometer miniaturization via a joint JPL-APL effort under the MatISSE program and JPL internal funding have led to the development of a hand-sized prototype instrument, the Ultra Compact Imaging Spectrometer (UCIS) (for details, see [2]). The UCIS prototype can be fitted with a variety of foreoptics for panoramic [3] or microscopic [4] imaging spectrsocpy investigations. Both were proposed for Mars2020 as MinMap [5] and CIMMBA [6], respectively, receiving Category 1 rankings. Presently, the UCIS prototype is operating at JPL, equipped with a spare focal plane array having a wavelength range of 500-2500 nm and breadboard foreoptics and an illumination system that achieves 81 μm/pixel spatial resolution on rock samples up to ~10 cm  ~10 cm in size with ~5 min required for data acquisition. Studies are being conducted for a variety of Earth and planetary science applications [e.g., 7, 8]. Utility for Meteorite Science in the Laboratory: VSWIR imaging spectroscopy provides a means of rapidly surveying the mineralogy and petrology of a meteorite, characterizing its compositional diversity and identifying key areas for followup investigation with very high resolution techniques that require sample preparation (e.g., SEM, TEM, FIBS, etc.). For our initial meteorite pilot study, we use a simple VSWIR