Curation of Chang’E-5 samples in France : containers opening and individual particle characterization

Introduction: The Chang’E-5 lunar mission collected samples in the north-eastern region of Oceanus Procellarum in December 2020 (Li et al., 2022; Zhou et al.,2022). Two lunar samples from Chang’E5 mission (hereafter CE5-FR) were donated to France. These samples are curated at the Muséum National d’Histoire Naturelle (MNHN) in Paris to conduct non-destructive characterization. These analyses will provide reference data before their allocation to the French scientific community under the supervision of CNES. We will describe the general workflow and results obtained by the analysis of the container gas composition and by a non-invasive and non-destructive characterisation of individual particles extracted from both samples.

Samples and methods: The CE5-FR samples arrived in France stored in glass vials within two aluminium containers. The first sample was ~1 gram of surface-scooped sample (CE5C0100) and the second ~0.5 gram of drilled sample (CE5Z0800). Upon reception the samples were stored under ultra-dry and ultra-pure nitrogen (<1 ppm O₂, <1 ppm H₂O). X-ray Computed Tomography (XCT) allowed to perform 3D images of containers' inside components and to identify the samples' general features, which include tens of large grains (> 100 µm) and grains with higher density and heterogeneities (probably agglutinates).

Gas analysis: We developed a dedicated gas extraction apparatus to recover the containers' gas in the CE5-FR dedicated glovebox. The containers’ base was punctured and the extracted gas transferred into bottles cleaned under high vacuum. The operation was repeated for both CE5-FR drilled and scooped containers. The concentrations of H₂O, O₂, CO₂, CO, and CH₄ were quantitatively determined at LIPhy laboratory using a custom-built direct absorption laser spectrometer (H₂O) and two ultra-sensitive cavity ring-down spectrometers (O₂, CO₂, CO, CH₄) (Chaillot 2023). The argon concentration and isotopic compositions were measured at IPGP on a Noblesse HR 3F6M noble gas mass spectrometer. The results indicate that large amounts of O₂ (~20.2%, ~13.9 %), CO₂ (~840 ppm, ~640 ppm) and argon (>0.7%, >0.01%) were present in the containers for scooped and drilled sample, respectively, with values suggesting significant abundance of terrestrial atmospheric gases.

Bulk sample and individual particles analysis: The global sample mass was measured in the glove box using a Sartorius TE64 balance, and the magnetic susceptibility was measured, in collaboration with the CEREGE team, with a SM150L instrument in a magnetic field of 80 A/m and a variable frequency from from 63 Hz to 16 kHz.

During the gas extraction procedure, a small fraction of the grains escaped from the vials and was recovered on the surface of the Teflon support within each container. We extracted hundreds of grains in a cleanroom environment at IJCLab, and performed characterisation of these particles using complementary non-invasive techniques. Grains with sizes ranging from ~50 to 300 µm were individually documented using a Keyence VHX-7000 digital optical microscope, revealing a large variety of colors, transparency (from opaque to transparent), and morphologies, including smooth crystals, rough surfaces, inclusions, and spherical beads.

Fourier Transform micro-Infrared characterisation (FTIR) of these individual particles was performed with the I2SES bench at IAS. FTIR spectra were measured in reflection mode with respect to gold standards, using a Bruker LUMOS II micro-spectrometer in the mid-infrared: 2.5- 15 µm (4,000-670 cm^-1) with a typical 50 x 50 µm spot size and spectral resolution of 4 cm^-1. A subset of particles was analysed using a Renishaw InVia Raman microspectrometer using a 532 nm laser. High-resolution XRD was performed at IMPMC using a Bruker D8 diffractometer equipped with a double set of Mo/Ag anodes and focussing optics, a large C28 Photon 3 CMOS detector and a unique motorized goniometer allowing microXRD mapping experiment with a ~100µm beam size at the sample position.

A fraction of the scooped sample (~90 mg) and one millimetre-sized grain were extracted in the CE5-FR glovebox and analysed at IAS for microscopic hyperspectral near-infrared (NIR) spectroscopic analysis by PTAL/MicrOmega under controlled atmosphere (Loizeau et al. 2021). A similar analysis will be performed on the drilled sample and the detailed results will be presented in another contribution (see T. Jiang et al. this conference).

Some particles with smaller sizes were identified on the metallic support used for vial manipulation of drilled sample in the glove box. We recovered these particles with conductive carbon tape and they were carbon coated for analysis by scanning electron microscopy (SEM) and later transmission electron microscope (TEM) investigations. The SEM images were performed using SEM-TESCAN instrument at MNHN, allowing to obtain secondary electrons (SE) and back-scattering electrons (BSE) images together with semi-quantitative analysis of major elements by X-ray energy dispersive spectroscopy (EDS).

Further analysis and sample preparation will be performed using a micromanipulator in a dedicated cleanroom at IPGP. A sub-fraction of the sample will undergo gamma-ray spectrometry at the CEA/LNHB to produce additional data to aid the interpretation of radon measurements made by Chang’E-6/DORN (Chacartegui Rojo et al. 2025, Meslin et al. 2025).

The overall dataset of individual particles and bulk batches will be assembled in a database that will be made available under CNES supervision. 

Acknowledgments:

We thank CNSA and the Chang’E-5 mission project for the gift of these lunar samples. This work was supported by DIM ACAV+ (Région Ile de France, C3E project), CNES (APR CE5-CURE), the MARCUS project (ANR-22-EXOR-0010, PEPR Origins). The I2SES bench was funded by DIM-Origins (I2SES project, PI. R. Brunetto), by MNHN, and ANR project LARCAS (grant ANR-22-CE49-0009). The work used the MNHN AST-RX platform for XCT analyses, TESCAN SEM microscope, and the MYRTHO cleanroom at IJCLab (supported by CNES). G.A was supported by the European Research Council (grant agreement n°101041122, project ATTRACTE). S.K. and H.F. thank the REFIMEVE network supported by ANR-11 EQPX-0039 and ANR-21-ESRE-0029.

References:

Li et al. 2022, National science review nwab188. Zhou et al. 2022, Advances in Space Research 823-836. Loizeau et al. 2020 PSS 193, 105087. Chacartegui Rojo et al. 2025, Applied Radiation and Isotopes 226, 112164. Meslin et al. 2025, EGU General Assembly, EGU25-14816. Chaillot, et al. 2025, Chemical Geology 673, 122450.