¹Xiaohui Fu,¹Chengxiang Yin,²Bradley L.Jolliff,¹Jiang Zhang,¹Jian Chen,¹Zongcheng Ling,¹Feng Zhang,³Yang Liu,³Yongliao Zou
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2022.115254]
¹Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong, China
²Department of Earth and Planetary Sciences and The McDonnell Center for the Space Sciences, Washington University in St. Louis, St. Louis, MO, USA
³State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
Copyright Elsevier

Chang’E-5 (CE-5) mission returned 1731 g of lunar soil from northeastern Oceanus Procellarum. This study begins by comparing the mineralogy and geochemistry of CE-5 soil with Apollo and Luna soils. CE-5 soil shares similar mineral components with Apollo mare soils. Geochemically, CE-5 soil is characterized by high-FeO, intermediate-TiO2, and elevated incompatible elements. The new returned CE-5 soil represents a unique type of mare soil that expands the diversity of returned lunar samples. Its bulk chemical compositions suggest that CE-5 soil consists of pulverized local mare basalt. Nonmare materials are thought to be negligible while meteoroid contamination is <1%. CE-5 soil provides an additional iron-rich basaltic end-member composition and extends the chemical ranges of the existing calibration soils for lunar remote sensing. CE-5 soil, together with the landing site, can serve as new ground truth both in mineralogy and geochemistry. Based on bulk chemical data of CE-5 soils and pyroxene compositions of CE-5 mare basalt clasts, we infer that CE-5 mare basalt has a fractional crystallization history similar to the Apollo high-Ti basalts. These CE-5 mare basalt clasts analyzed in recent studies, possibly derive from a single lava flow that experienced strong fractional crystallization.

¹Laura M.Barge,¹Erika Flores,¹Jessica M.Weber,¹Abigail A.Fraeman,^1,2Yuk L.Yung,³David VanderVelde,⁴Eduardo Martinez,¹Amalia Castonguay,¹Keith Billings,⁴Marc M.Baum
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2022.08.038]
¹NASA Jet Propulsion Laboratory, California Institute of Technology
²Division of Geological and Planetary Sciences, California Institute of Technology
³Department of Chemistry, California Institute of Technology
⁴Department of Chemistry, Oak Crest Institute of Science
Copyright Elsevier

Iron minerals are highly reactive drivers of abiotic / prebiotic organic chemistry, and in the presence of ammonia (NH3/NH4+) or other reduced nitrogen (N) compounds, have been shown to promote amino acid synthesis from organic precursors. On early Mars, oxidized nitrogen species (NOx-) such as NO3- and/or NO2- may have been present, which could be reduced by Fe(II) to form various species including N2O and/or NH3/NH4+. The production of NH3/NH4+ from Fe(II)-driven NO3- or NO2- reduction may be able to feed into prebiotic organic reactions including amino acid formation. In this study, we tested whether iron mineral-driven reduction of NO3- or NO2- could provide a source of NH3/NH4+ to form amino acids from two prebiotically relevant precursors (pyruvate and glyoxylate); or, whether an exogeneous source of NH3/NH4+ would be required. We observed that pyruvate and glyoxylate reacted with Fe-oxyhydroxide minerals in NOx–containing experiments to form reduced hydroxy acid products; and in experiments containing only NH3/NH4+, amino acids were also formed. However, significant amino acid formation was not observed in any experiments containing NO3- or NO2- unless sufficient NH4+ was also added; furthermore, colorimetric analysis did not show any generation of NH4+ from NO3- / NO2- reduction at these conditions. NO2- was observed to be highly reactive with Fe2+ and Fe(II)-bearing minerals, resulting in Fe oxidation during mineral precipitation and the formation of oxidized mineral phases (hematite). The Fe(II)/Fe(III) ratio in oxyhydroxide minerals is an important parameter for determining organic product distributions from pyruvate and glyoxylate; therefore, Fe-mediated NOx- reduction does impact organic chemistry. However, amino acid formation, at least under these conditions, would also require an exogenous source of NH3/NH4+ or other reduced N species. These results have implications for organic-N chemistry on early Mars, as well as for some early Earth origin of life scenarios regarding organic synthesis in mineral-containing systems.