During the six Apollo missions, astronauts collected 2196 lunar samples, nearly all of which have been studied over the past five decades. Six Apollo samples remained unexamined until 2019 and were saved to be analyzed by the next generation of lunar scientists using advanced modern laboratory facilities. Now more than 50 years after Apollo, NASA is returning to the Moon with Artemis and will return geologic samples from a different region of the lunar surface than Apollo. Curation will play an instrumental role in helping to prepare for the safe return of these valuable samples, ensuring their integrity during all stages of the missions, and thus maximizing their scientific return. To prepare for the return of these samples, NASA initiated the Apollo Next Generation Sample Analysis (ANGSA) Program to open previously unstudied samples including unopened double drive tube 73002 and 73001 (also vacuum-sealed) from the Apollo 17 mission to the Taurus-Littrow Valley. The ANGSA program was designed to function as a low-cost analog sample return mission and served as a testing ground to understand processes, update techniques, and prepare for the preliminary examination (PE) of the to-be-returned lunar samples with Artemis. New and advanced curation techniques were developed and applied to support the analyses of 73002/73001 during the PE. Furthermore, cutting-edge analytical instruments such as X-ray Computed Tomography were utilized to aid in PE that were unavailable during Apollo. These efforts are equipping the Artemis generation for future lunar missions and lessons learned from the PE of ANGSA samples will be directly applied to Artemis.
Models of planetary core formation traditionally involve the fractionation of Fe,Ni-metal melts from silicate mantles after extensive silicate melting. However, in planetary bodies that form farther from their central star, where moderately volatile elements are more abundant, high concentrations of oxygen and sulfur stabilize Fe,Ni-sulfides over metals. Here we show that percolative sulfide melt migration can occur in primitive, oxidized mineral assemblages prior to silicate melting in partial melting experiments with meteorites. Complementary experiments with partially molten synthetic sulfides show that fractionation of liquid sulfide from solid residues yields distinct noble metal (Os, Ru, Ir, Pd, and Pt) trace element proportions that match those manifested in the most oxidized meteoritic residues, the brachinites, as well as their complementary basaltic silicate melts. Our experiments provide robust evidence for percolative sulfide melt fractionation in meteorites and indicate that sulfide-dominated cores would be expected in oxidized planetary bodies, including Mars.
A major objective of the Mars 2020 mission is to sample rocks in Jezero crater that may preserve organic matter for later return to Earth. Using an ultraviolet Raman and luminescence spectrometer, the Perseverance rover detected luminescence signals with maximal intensities at 330 to 350 nanometers and 270 to 290 nanometers that were initially reported as consistent with organics. Here, we test the alternative hypothesis that the 330- to 350-nanometer and 270- to 290-nanometer luminescence signals trace Ce3+ in phosphate and silicate defects, respectively. By comparing the distributions of luminescence signals with the rover detections of x-ray fluorescence from P2O5 and Si-bearing materials, we show that, while an organic origin is not excluded, the observed luminescence can be explained by purely inorganic materials. These findings highlight the importance of eventual laboratory analyses to detect and characterize organic compounds in the returned samples.
On 24 September 2023, the NASA OSIRIS-REx mission dropped a capsule to Earth containing approximately 120 g of pristine carbonaceous regolith from Bennu. We describe the delivery and initial allocation of this asteroid sample and introduce its bulk physical, chemical, and mineralogical properties from early analyses. The regolith is very dark overall, with higher-reflectance inclusions and particles interspersed. Particle sizes range from sub-micron dust to a stone about 3.5 cm long. Millimeter-scale and larger stones typically have hummocky or angular morphologies. A subset of the stones appears mottled by brighter material that occurs as veins and crusts. Hummocky stones have the lowest densities and mottled stones have the highest. Remote sensing of the surface of Bennu detected hydrated phyllosilicates, magnetite, organic compounds, carbonates, and scarce anhydrous silicates, all of which the sample confirms. We also find sulfides, presolar grains, and, less expectedly, Na-rich phosphates, as well as other trace phases. The sample composition and mineralogy indicate substantial aqueous alteration and resemble those of Ryugu and the most chemically primitive, low-petrologic-type carbonaceous chondrites. Nevertheless, we find distinct hydrogen, nitrogen, and oxygen isotopic compositions, and some of the material we analyzed is enriched in fluid-mobile elements. Our findings underscore the value of sample return, especially for low-density material that may not readily survive atmospheric entry, and lay the groundwork for more comprehensive analyses.
This study analyzed samples of the Murchison and Sutter's Mill carbonaceous chondrite meteorites in support of the future analysis of samples returned from the asteroid (10155) Bennu by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) mission. Focusing specifically on the insoluble organic matter (IOM), this study establishes that a total of 1.3 g of bulk sample from a single chondritic meteorite are sufficient to obtain a wide range of cosmochemical information, including light element analysis (H, C, and N), isotopic analysis (D/H, 13C/12C, and 15N/14N), and x-ray fluorescence spectroscopy for major elemental abundances. IOM isolated from the bulk meteorite samples was analyzed by light element and isotopic analysis as described above, 1H and 13C solid-state nuclear magnetic resonance spectroscopy, Raman spectroscopy, and complete noble gas analyses (abundances and isotopes). The samples studied included a pair from Murchison (CM2), one of which had been irradiated with high-energy x-rays in the course of computed tomographic imaging. No differences between the irradiated and non-irradiated Murchison samples were observed in the many different chemical and spectroscopic analyses, indicating that any x-ray-derived sample damage is below levels of detection. Elemental, isotopic, and molecular spectroscopic data derived from IOM isolated from the Sutter's Mill sample reveals evidence that this meteorite falls into the class of heated CM chondrites.
X-ray computed tomography (XCT) is a valuable reconnaissance tool for three-dimensional imaging and identification of distinct lithologies in extraterrestrial samples. It will be used as part of the preliminary examination of samples returned from asteroid (101955) Bennu by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. However, it must first be established whether x-rays generated during XCT could degrade or alter the organic composition of the returned samples by radiolysis. To test this, we split a crushed sample of the Murchison CM2 meteorite, kept one portion as a control, and irradiated the other portion up to the maximum x-ray dosage (similar to 180 Gy) that a Bennu sample would experience during an XCT imaging experiment. We then extracted organic compounds from both splits and conducted (i) nontargeted soluble organic analyses to compare the chemical distributions of C-, H-, O-, N-, and S-bearing species and (ii) targeted measurements to quantify the abundances of 96 individual soluble organic molecules that included protein amino acids, amines, carboxylic acids, hydroxy acids, carbonyl compounds, polycyclic aromatic hydrocarbons, alcohols, sugars, and N-heterocycles. We found that XCT imaging of the Murchison meteorite had no measurable impact on the relative abundances or enantiomeric compositions of most of the soluble organic compounds targeted in this study. Elevated total abundances of several soluble organic compound classes were observed in the XCT-scanned Murchison sample relative to the control. This is likely related to particle size heterogeneity and specific surface area differences between the sample aliquots used for the extractions, rather than a result of the x-ray exposure. Assuming the samples returned from asteroid Bennu by OSIRIS-REx have a similar composition to carbonaceous chondrites, these data provide confidence that XCT will not significantly alter their soluble organic compositions.
Several lunar samples collected during the Apollo missions were kept sealed and stored in controlled conditions in order to be studied decades later exploiting future, more advanced capabilities. Two of the preserved samples are Apollo 17 double drive tube 73002/73001. The double drive tube extracted a core sample of the Light Mantle deposit at Station 3 in the Taurus-Littrow Valley (Figure 1). As part of the NASA Apollo Next Generation Sample Analysis (ANGSA) program, samples 73002 and 73001 became available to study in 2019 and 2022, respectively [1][2]. The Apollo 17 double drive tube sampled the Light Mantle deposit material down to a depth of 70.6 cm; the effective material length of each tube is 21.3 cm for 73002 and 34.9 cm for 73001 (some material was lost during sampling). This represents an unprecedented opportunity to study the Light Mantle deposit to previously unsampled depths.The Light Mantle deposit represents the only extraterrestrial landslide to have ever been studied in-situ. The Light Mantle is a 5-km-long deposit that formed from debris mobilised from the South Massif, a 2.2-km-high mountain in Taurus-Littrow Valley [3][4]][5]. The origin and hypermobility of the Light Mantle remain debated. The recently opened Apollo 17 double drive tube 73002/73001 provides a new set of samples to investigate the origin and the emplacement mechanisms of the Light Mantle.Prior to dissection and opening of the sample containers, the double drive tube was scanned using X-ray computed tomography (XCT) [6] so that a digital, high-resolution 3D dataset of the whole core sample is available and represents one of the ‘next generation’ capabilities now available to researchers to interrogate the data using novel approaches and obtain new insights into lunar material and processes. Additionally, the 3D dataset preserves the 3D context of all the subsamples extracted from the original core sample.In this work, we used high-resolution X-ray computed tomography (XCT) scans and high-resolution scans of thin sections of the upper 20 cm of the core, sample 73002, and conduct 3D clast-size analysis and investigation of clast morphological fabric. The aims of this work are to:Present a 3D data processing workflow that can be used as a basis for future investigations of lunar core samples. Demonstrate potential scientific information that can be extracted from 3D analysis of lunar core samples. Within this framework, we conduct: (1) 3D grain size analysis and compare the results with grain size analyses conducted on the grains extracted during the dissection of the core sample; (2) 3D analysis of clast size distribution. Additionally, as part of our investigation of the emplacement mechanism of the Light Mantle, we use 2D continuous thin sections (backscattered electron maps) of sample 73002 to search for diagnostic clast fabric similar to those generated during the friction experiments conducted in simulated lunar landslides [7]. The clast fabric is called Clast Cortex Aggregate (CCA) and it’s constituted by a central clast surrounded by nano-scale fine material (Figure 2).The data analysis and visualization of the XCT dataset of core sample 73002 were performed using 3D visualization software Avizo 2022.2 by ThermoFisher. We customized our workflow and established a best-practice protocol so that they can be used as reference for future analysis of 73001. We used backscattered electron (BSE) maps of the sample’s thin sections (73002,6011; 73002,6012; 73002,6013; 73002,6014) [8] to search for (CCAs).The results of clast-size distribution show that the sample is characterised by lack of the largest clast-size fraction in the top 4-5 cm, which we attribute to the fragmentation of larger regolith-hosted clasts and bedrock by space weathering and meteoroid bombardment. The observation of an uppermost layer presenting characteristics of reworked regolith is consistent with results from previous studies of lunar regolith and from other works conducted on 73002 as part of the ANGSA program [8][9]. Moreover, we found extensive presence of CCAs. The formation of CCAs in natural and lab-simulated landslides is attributed to granular flow dynamics, presence of nanoparticles, and adhering forces between such particles. Therefore, we concluded that the presence of CCAs in sample 73002 represents the first evidence that the Light Mantle was emplaced as a granular flow. This work shows that valuable information can be extracted from the 3D analysis of lunar core samples and, more generally, it shows the potential of morphometric and morphological clast analysis using high resolution XCT dataset and thin sections combined.Our work represents the first study to conduct a 3D clast analysis of a lunar regolith core sample. As such, it constitutes an important step in showing the novel information that can be extracted, and presenting a potential workflow for studying lunar regolith core samples that will be collected during future missions to the Moon. REFERENCES. [1] Shearer et al. (2020). AGU Fall Meeting. Abstract V013-0001. [2] Shearer et al. (2022). 53rd LPSC. Abstract 2546. [3] Schmitt (1973). Science, 182(4113), 681–690. [4] Lucchitta (1977). Icarus, 30(1), 80–96. [5] Kokelaar et al. (2017). JGR:Planets, 122(9), 1893-925. [6] Gross et al. (2023). https://curator.jsc.nasa.gov/lunar/angsa_attachments/aapreliminary_20catalog/preliminary_73001-73002_catalog.pdf. [7] Magnarini et al. (2023). JGR:Planets, 128(6), e2022JE007520. [8] Bell et al. (2024). Submitted to JGR:Planets – In review. [9] Neuman et al. (2024). Submitted to Science – In review.Figure 1 – a) Oblique view of Taurus-Littrow Valley; the yellow dot shows the location of the Apollo 17 landing site (LROC/NAC image M1266925685L. Image credit: NASA/GSFC/ASU); b) A frame from the original footage recorded from the Lunar Rover Vehicle onboard camera the showing astronaut Gene Cernan extracting the double drive tube containing material from the Light Mantle deposit. c) Double drive tube in the ground prior extraction (AS17-137-20981. Image credit: NASA). The yellow star in the three panel shows the location where the double drive tube core sample 73002/73001 was collected. Figure 2 – Comparison of Clast Cortex Aggregates (CCAs). (a-b) CCAs generated during the friction experiments conducted on anorthosite-bearing gouges by [7]; (c-f) CCAs found in the Apollo 17 core sample 73002. The red dotted lines and the white dotted line in (d) show the corona of finer fragments found around clasts.
meteorites are the only physical materials on and multiple microanalytical methods applied to providing a wealth of information on Martian geologic history—from accretionary processes to recent hydrothermal activity. there is a paucity of published work using X-ray computed tomography (CT) to investigate Martian meteorites even though it is a non-destructive technique well suited for characterization of Here we present a subset of results from a larger CT survey of Martian meteorites that illustrates the new kinds of information that can be gained from CT, demonstrating its utility for non-destructive examination of new and returned astromaterials, as well as enhancing the scientific return from destructive analyses.
In this study, we utilize high-resolution X-ray computed tomography (XCT) to track the progress of a leaching process within a pore network. Dissolution and leaching are difficult processes to observe with combined temporal and spatial context, particularly when dissolving material within a non-reactive pore network, and XCT is a uniquely suited technique for observing dissolution in situ, and extracting quantitative data on pore networks and the material in them in 3D. We XCT image two samples of porous diamond (carbonado) during a sequential acid leaching procedure designed to remove a diverse assemblage of pore-filling minerals. This experiment provides a unique perspective for observing mineral dissolution in 4D, allowing us to identify differences in mineral inclusions and pore network topology between carbonado samples based on dissimilar dissolution styles and rates. We are also able to observe the formation of fluorides during acid digestion, which can persist throughout acid leaching procedures and drastically affect yields for geochemical measurements of certain elements, most importantly REEs, U, Th, and Pb. We test various approaches to measuring porosity, finding that methods based on quantitative interpretation of CT numbers as partial porosity give more accurate results than purely binary segmentation, and that attempts to segment the pore network using visual criteria are scattered and unreliable. We document how image quality can be locally affected by material properties, with filled pores measurably blurrier than empty ones. Such local variation in point-spread function is important when segmenting XCT data for the purposes of quantification. Finally, we demonstrate that by comparing mass and X-ray attenuation loss it is possible to estimate the relative heavy-metal content of the leached material.