22-EPN3-046: Integrated Spectroscopic Study of Apollo 16 Sample and Anorthositic Lunar Meteorite
Visit by Prateek Tripathi, Indian Institute of Technology, Roorkee (India) to TA2 Facility 5 – DLR Planetary Spectroscopy Laboratory (Germany).
Dates of visit: 10-17 December 2023
Report Summary: The objective was to characterise 15 lunar minerals, the Apollo 16 sample, and the Tissertiline lunar meteorite using integrated spectroscopy with the Bruker Vertex80V FTIR instruments at the Planetary Spectroscopy Laboratory (PSL). The minerals studied included pigeonite, augite, ilmenite, orthopyroxenes, olivine, anorthite, and bytownite, with grain sizes ranging from 25-125 μm. Additionally, Apollo 16 sample 62231.44, collected from the rim of Buster Crater and highly mature, was included in the analysis. The methodologies employed integrated bidirectional reflectance spectroscopy in the visible (VIS) and near-infrared (NIR) ranges at 30° and 45° angles, separate hemispherical measurements in VIS and NIR, and emission spectroscopy at temperatures of 70°C, 100°C, and 130°C over the mid-infrared range. The spectral range covered was 0.2 – 150 μm, with a resolution ranging from 0.1 – 8 cm⁻¹. In total, 204 spectra were acquired in ten days of visit, including standards (endmembers/lunar minerals), the Apollo 16 sample, the lunar meteorite, and a black body.
Bidirectional measurements yielded 102 spectra (VIS and NIR separately), hemispherical measurements provided separate VIS and NIR spectra totaling 51, and emissivity measurements contributed 51 thermal emission spectra. This comprehensive methodology allowed for the observation of the effects of temperature and grain size on spectral properties. This integrated optical through thermal spectroscopy approach successfully characterises lunar sample and results in a spectral library that will aid in the interpretation of future lunar mission data for composition identification and resource potential
assessment.
