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Introduction: Carbonaceous chondrites are among the most well-studied meteorite types and have played a vital role in deciphering the origin and evolution of our solar system. They have been linked to low-albedo C-type asteroids [1, 2], but due to subdued absorption bands, definitive asteroid-meteorite linkage remains elusive. Recent spacecraft missions to near-Earth asteroids (NEAs), such as Bennu and Ryugu, have shown that their surfaces are dominated by larger grain size material [3, 4] unlike the fine regolith that is observed on the Moon and larger NEAs like Eros [5, 6]. A majority of the existing spectral database are based on powdered meteorite samples (typically <45 µm) across a limited wavelength range (typically 0.35-2.5 µm) making it challenging to interpret spectra of small NEAs. In this work, we present the results of our study to constrain the grain size effects on spectra of six carbonaceous chondrite groups over a wide wavelength range (0.2-15 µm). Broad trends in grain size across the meteorite groups were observed in absolute reflectance, slope, and band characteristics. This work was done as part of PTYS 520 Meteorites class (Spring 2022) at the Lunar and Planetary Laboratory, University of Arizona. Meteorite Selection: Due to the difficulty of crushing metal, we chose to exclude the carbonaceous chondrite types that were high in metal content: CBs and CHs. The low availability of CI chondrites also led us to exclude them from this study. This left us with five main carbonaceous chondrite groups (CM, CO, CV, CR, and CK) as well as one ungrouped type (C2). Samples were selected from the University of Arizona collection. Sample Preparation: Samples from large slices were first dry-cut with a band saw to obtain a smaller sample piece and preserve extraneous material for future study. Then, each meteorite sample was hand-crushed with an alumina mortar and pestle and dry-sieved to five grain size classes: 45-90, 90-150, 150-300, 300-500, and 500-1000 microns. Crushing and sieving took place sequentially until at least 0.30 g of material was obtained for each grain size corresponding to each meteorite. Sample powders were then transferred into 3D-printed, black sample cups and leveled with a glass slide. Experimental Setup: Ultraviolet to visible reflectance spectra (0.20-0.60 µm) was acquired with an Avantes UV Spectrometer at i = 0° and e = 0° relative to a calibrated Spectralon standard with a combined deuterium arc lamp quartz-halogen light source. Visible and near-infrared reflectance spectra (0.6-2.5 µm) of our samples was taken using an ASD FieldSpec Pro HR spectrometer at i =30° and e = 0°, relative to a calibrated Spectralon standard, with a collimated 100W quartz-tungsten-halogen light source. Mid-infrared reflectance spectra (2.5-15 µm) was acquired with a ThermoFisher Nicolet FTIR at i = 0° and e = 0° relative to a diffuse gold standard with a silicon nitride globar light source. Results: Spectral slope in the 0.6-2.5 µm wavelength range was measured for all six samples. All grain sizes of Ungrouped C2 Tarda have a red spectra slope (increasing reflectance with increasing wavelength) across all grain sizes. In contrast, CM2 Aguas Zarcas and CR2 NWA 10324 have neutral to red spectral slope for smaller grain size that changes to blue slope (decreasing reflectance with increasing wavelength) at larger grain sizes. The spectra of the other three types (CO3.2, CV3, CK4) have blue slopes that do not qualitatively change with grain size. Tarda has the lowest 0.55 µm (photometric V filter) reflectance (<3%) and CK4 NWA 10563 is the brightest at (~8%). All samples show very minor changes in 0.55 µm reflectance with grain size. Band depth of the 1.1 µm olivine/pyroxene absorption for 45-90 microns grain size shows variation across the six types we studied. Futher analysis of all detected absorption bands and any correlations with grain size is ongoing. Acknowledgments: This work was funded by NASA YORPD Program grant 80NSSC22K0514 (PI: Reddy). [ABSTRACT FROM AUTHOR]

Introduction: S-complex asteroids dominate the large near-Earth asteroid (NEA) population and some have been linked to ordinary chondrite meteorites [e.g., 1]. There is, however, a discrepancy between the percentage of ordinary chondrites in the meteorite collection (~85%) [2] versus the percent of NEAs with ordinary chondrite-like compositions. Several non-compositional effects on an asteroid surface and in the observation process can alter the visible and near infrared (VNIR) spectrum (0.35-2.5 μm) of the asteroid, potentially leading to a misidentification of meteorite analogs. We analyze VNIR spectra of NEA 1998 OR2 and find some of the first evidence of shock darkening processes altering an NEA surface. Spectroscopy Derived Surface Mineralogy: Visible spectra (0.45-0.93 μm) of 1998 OR2 were collected on 2020 April 16 using the Robotic Automated Pointing Telescope for Optical Reflectance Spectroscopy I (RAPTORS I) telescope at the University of Arizona. The measured low resolution (R~30) visible spectra were combined with MITHNEOS [1] archival near infrared (NIR; 0.78-2.49 μm) spectra from the NASA Infrared Telescope Facility. The combined VNIR spectroscopy shows a very flat spectrum with two shallow absorption bands which are diagnostic of olivine and pyroxene surface mineralogy [3]. The best matching taxonomic classification for the observed spectrum is Xn-type, as measured by the SMASS online tool [4]. The absorption bands were noted to be suppressed compared to typical absorption bands seen on S-complex asteorids, indicating the likely precense of an alteration process or noncompositional affects on the data. Measurements of the following diagnostic band parameters were taken: Band I at 0.926 ± 0.003 μm and Band II at 2.07 ± 0.02 μm; Band I depth of 4.5 ± 0.15% and Band II depth of 4.0 ± 0.21%; Band Area Ratio of 1.13 ± 0.05. Further analysis of these band parameters using the equations from [5-6] indicate that this is a composition consistent with H chondrites. Non-compositional Effects: In order to understand the suppressed band features of the VNIR spectra, we investigated effects from phase reddening, space weathering, grain size, and shock darkening. We were able to rule out phase reddening because the NIR observations were at a relatively low phase angle (40.2°) and 1998 OR2's observed spectrum was very flat. Principal component analysis was used to eliminate the hypothesis that space weathering or grain size effects were causing the observed spectral features. Shock darkening is an ideal candidate for explaining the observed spectral features because it causes supressed absorption band features without reddening the asteroid spectrum. Shock darkening is also supported by principal component analysis placing 1998 OR2 near the end of the shock darkening trend measured by [1] in principal component space. Meteorite Analog: A comparison of meteorites in the RELAB database with 1998 OR2's spectrum using the Modeling For Asteroids (M4AST) tool returned shock darkened ordinary chondrite McKinney as the best potential meteorite analog [7-8]. In order to perform our own analysis, shock darkened H5 ordinary chondrite Chergach was selected for comparison with 1998 OR2. Our sample of Chergach was loosely broken apart and the dark and light lithologies were separated by hand. The dark and light lithologies were separately crushed and dry sieved to < 45 μm. Spectra of each endmember were obtained with an ASD spectrometer to obtain a VNIR spectrum for comparison with 1998 OR2. Both the meteorite spectra and the 1998 OR2 spectrum were continuum corrected and normalized at 1.5 μm. An aerial mixing model was used to mathematically mix the two endmembers and calculate a chi-squared value to quantify the goodness of fit between the meteorite mixture and 1998 OR2's spectrum. The mixture with the lowest chi-squared value was chosen as the best fit for the mixture and allows us to constrain the amount of shock darkened material on the asteroid. The best-fit match with 1998 OR2 corresponds to a 37:63 light/dark lithology mixture. Acknowledgments: This research work was supported by NASA Near-Earth Object Observations grant NNX17AJ19G (PI: Reddy). This research has made use of the Small Bodies Data Ferret, supported by the NASA Planetary System. Part of the data utilized in this publication were obtained and made available by the MIT-Hawaii Near-Earth Object Spectroscopic Survey. Observations reported here were obtained at the Infrared Telescope Facility, which is operated by the University of Hawaii under Cooperative Agreement NCC 5-538 with the NASA, Science Mission Directorate, Planetary Astronomy Program. Taxonomic type results presented in this work were determined, in whole or in part, using a Bus-DeMeo Taxonomy Classification Web tool by Stephen M. Slivan, developed at MIT with the support of National Science Foundation Grant 0506716 and NASA Grant NAG5-12355. [ABSTRACT FROM AUTHOR]

This study compared the usefulness of the pulse rate and ventilation rate in the prediction of energy cost. Four young men were exercised at six grades on the motor-driven treadmill in order to derive data for regression equations, one to predict oxygen consumption from pulse rate data and the other using the ventilation rate. Separate equations were derived for each subject. The precision of prediction was then tested in three work tasks including treadmill walking while holding a weight in a static contraction, cycling the bicycle ergometer and hand-cranking the ergometer. Although large mean differences in percentage error were recorded in the pulse rate prediction, they were not statistically significant, probably due to large individual variations. The differences in ventilation rate prediction were significant and indicated the need for using closely related activities when deriving the predictive equations. Prediction accomplished with the ventilatory data resulted in smaller errors than did the pulse rate predictions. [ABSTRACT FROM PUBLISHER]