Curation activities progress on the Chang’E-5 samples in France

China’s Chang’E-5 (CE-5) mission successfully returned 1,731 grams of lunar samples from the northeastern region of Oceanus Procellarum in December 2020 (C. Li et al., 2022; Zhou et al., 2022). The landing site, among the Moon’s youngest mare basalts (Morota et al., 2011; Qian et al., 2021; Che et al., 2021; Li et al., 2021), is located at a higher latitude than those explored by NASA’s Apollo and the USSR’s Luna missions, offering a unique opportunity to study previously unexamined lunar material.

Approximately 1 gram of surface-scooped sample (CE5C0100) and 0.5 gram of drilled sample (CE5Z0800) were offered to France. These samples are currently stored at the Muséum National d’Histoire Naturelle (MNHN) in Paris in a dedicated glovebox under ultra-dry and ultra-pure nitrogen. A curation project was initiated to conduct non-destructive, preliminary characterization of the samples and provide reference data before their allocation to the French scientific community under the supervision of CNES. The proposed curation activities are described below.

The CE-5 samples arrived in France stored in glass vials within an aluminum container. To obtain preliminary data on both the samples and containers, X-ray Computed Tomography (XCT) was performed at AST-RX platform (MNHN). The XCT scans at a spatial resolution of 60 µm/pixel enabled measurement of the container’s bottom thickness (~5 mm), empty volume (~800 cm³), and sample volumes (~700 mm³ for the scooped sample and ~360 mm³ for the drilled sample). The XCT images also identified 10–20 grains larger than 500 µm and revealed grains with higher density, heterogeneity, or void space (possible agglutinate).

The container will be opened in a glovebox at MNHN under a controlled atmosphere (<1 ppm O₂ and <1 ppm H₂O). Part of the samples will be transferred to a new custom-made glovebox in a dedicated clean room (ISO7) at Institut de Physique du Globe de Paris (IPGP). A gas extraction procedure will be performed on the drilled sample container using a custom-designed extraction system developed in collaboration between IMPMC and IPGP. The container’s base will be punctured, and the gas will be transferred into an ultra-high vacuum bottle. The gas will then be analysed using a custom-built infrared optical spectrometer at Liphy (CNRS, Grenoble Alpes University).

Non-invasive measurements—including mass and magnetic susceptibility—will be conducted on each bulk sample in the vials. The samples will then be separated in different batches and transferred to a stainless-steel cylinder with a glass window for storage. An optical sensor on the glass window will allow continuous monitoring of O₂ levels inside the cylinder without opening it.

Rehearsals will be conducted using new equipments, including a micro-manipulator located in a new glovebox and dedicated materials and tools to test manipulation, measurements and storage procedures. We are planning to extract the largest grains from the bulk material for dedicated characterization. Both bulk powder and grain samples will undergo basic weighing and imaging. Subsamples will be placed on sapphire dishes, sealed in faculty-to-faculty transfer containers (FFTCs), and sent to collaborating laboratories for infrared spectroscopy, XCT, and X-ray diffraction (XRD). The remaining samples will remain untouched in the storage cylinders in the glovebox at MNHN for future analysis.

Infrared microanalysis of both bulk powder and large grains will be conducted at the Institut d'Astrophysique Spatiale (IAS) using MicrOmega (near-infrared: 0.99–3.65 µm, 22 µm/pixel, Bibring et al., 2017) and FTIR (mid-infrared: 2.5-12.5 µm (4,000-800 cm^-1), 5 µm/pixel). Both hyperspectral imagers will aid in identifying characteristic mineral phases (e.g., olivine, pyroxene, plagioclase) in the samples. High-resolution XRD will be conducted at IMPMC, while XCT analysis at micron or sub-micron scale of large grains will be performed at the French synchrotron facility SOLEIL.

These analyses will provide a comprehensive dataset to documenting the samples’ mass, morphology, and mineralogy of both individual grains and bulk-powder batches. The results will be compiled into a catalog database and shared via a dedicated website under CNES supervision. Further details will be presented at the conferences.

 

Acknowledgements:

We thank the Chang’E-5 mission project for sharing these invaluable lunar samples. We also thank CNES for its full support on the curation activities. The curation activities at MNHN received funding from DIM ACAV+ (Région Ile de France, project C3E), CNES (APR CE5-CURE), the PEPR Origins, project MARCUS (ANR-22-EXOR-0010). The X-ray Computed Tomography (XCT) was performed at the AST-RX, plateau d'Accès Scientifique à la Tomographie à Rayons X du MNHN, UAR 2700 2AD CNRS-MNHN, Paris.

 

References:

Bibring, J-P., et al. "The micrOmega investigation onboard Hayabusa2." Space Science Reviews 208 (2017): 401-412.

Che, Xiaochao, et al. "Age and composition of young basalts on the Moon, measured from samples returned by Chang’e-5." Science 374.6569 (2021): 887-890.

Li, Chunlai, et al. "Characteristics of the lunar samples returned by the Chang’E-5 mission." National science review 9.2 (2022): nwab188.

Li, Qiu-Li, et al. "Two-billion-year-old volcanism on the Moon from Chang’e-5 basalts." Nature 600.7887 (2021): 54-58.

Morota, Tomokatsu, et al. "Timing and characteristics of the latest mare eruption on the Moon." Earth and Planetary Science Letters 302.3-4 (2011): 255-266.

Qian, Yuqi, et al. "China's Chang'e-5 landing site: Geology, stratigraphy, and provenance of materials." Earth and Planetary Science Letters 561 (2021): 116855.

Zhou, Changyi, et al. "Scientific objectives and payloads of the lunar sample return mission—Chang’E-5." Advances in Space Research 69.1 (2022): 823-836.