Ground Verification Test of Lunar Mineralogical Spectrometer on the Chang’e 5 Lunar Sample Return Lander

Abstract:

The Chinese Chang’e 5 (CE-5) lunar sample return mission is scheduled to launch in 2017 to bring back surface regolith and drill samples from the northeastern Oceanus Procellarum region on the Moon. The Lunar Mineralogical Spectrometer (LMS) on the CE-5 lander is a VIS/IR imaging spectrometer (0.48 μm -3.2 μm) designed to analyze the mineralogical composition of the sample return site. LMS employs acousto-optic tunable filters (AOTFs) and is composed of a VIS/NIR module (0.48 μm -1.450 μm) and an IR module (1.4 μm -3.2 μm). It has spectral resolution in the range of 5-25 nm, with a field of view (FOV) of 3°×3°. An aluminum plate and an Infragold plate are used as calibration targets in the VIS/NIR and IR spectral range, respectively. Before launch, a ground verification test of LMS needs to be conducted in order to: 1) test and verify the performance of LMS through evaluation of the quality of image and spectral data collected with simulated lunar samples in the lab; and 2) calculate calibration parameters for calibration on the Moon through simulation of instrument calibration on the ground. The ground verification test will be conducted both indoors (for NIR to medium wavelength IR) and outdoors (for VIS to short wavelength IR). The indoor test will be conducted under condition of <60% relative moisture content, to reduce the effect of water vapor absorption near 2.7 μm. The spectra of simulated lunar regolith/mineral samples in the 2.5 μm -3.2 μm range will be collected simultaneously by the LMS and a calibrated FT-IR spectrometer (Model 102F). The outdoor test will be conducted with solar incidence angle >75° and relative moisture content <60%. The spectra of simulated lunar regolith samples in the 0.48 μm -2.5 μm range will be collected simultaneously by the LMS and a calibrated VIS/IR spectrometer (ASD FieldSpec 4 Hi-Res). In this paper we report the results of the LMS ground verification test regarding the evaluation of LMS spectral and image data quality, mineral identification and inversion ability, and calibration accuracy and geometric positioning accuracy.