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Microtektites represent high-velocity/distal meteorite impact ejecta. Demonstrating that microtektites found at several locations throughout East-Antarctica consist of a homogeneous class of geological objects belonging to the Australasian tektite/microtektite strewn field is fundamental to define the actual extent of the largest and youngest known tektite field on Earth produced by an asteroidal impact ∼0.8 Ma ago. This study presents new 40Ar/39Ar analyses performed by multi-collector noble gas mass spectrometry on individual microtektites from two key locations in the Transantarctic Mountains: Miller Butte, in northern Victoria Land, and Mount Raymond, over 1,000 km further south, in the Grosvenor Mountains. Results indicate that particles are heavily contaminated by at least one extraneous Ar component, which is not correlated with size nor with bulk chemical composition, and precludes a straightforward interpretation of 40Ar/39Ar data. Analysis of data from step-heating and total fusion analyses in three-isotope correlation diagrams yielded indistinguishable isochron ages from the two locations, with a combined isochron average of 800 ± 89 ka (95% confidence level). These age results improve by more than one order of magnitude previously published 40Ar/39Ar age determinations and improve by ∼4 times a previous fission track date, thus providing conclusive evidence that microtektites found throughout the Transantarctic Mountains of Antarctica belong to a single source – the Australasian field. This study strengthens the southward extension of the Australasian field (∼4,000 km southward with respect to Australasian microtektites recovered at lower latitudes from deep sea sediments), thus implying a launch distance of nearly 12,000 km from the putative impact location in Indochina. From a broad perspective, results also reveal a contrasting behavior between microtektites from the Transantarctic Mountains, highly contaminated by extraneous Ar, and Australasian macroscopic tektites, weakly or negligibly contaminated. Although future dedicated experimental work, aimed at the definition of physical homogeneity of microtektites at the submicroscale and at the understanding of the true intra-particle spatial distribution of Ar isotopes are necessary, we speculatively hypothesize that the contrasting behavior between tektites and microtektites may reflect displacement in different environments.

International audience; In his welcome commentary on our paper (Rochette et al. 2018), Mizera (2019) challenges our preferred interpretation for the Australasian tektite (AAT) source: soil-covered old continental sediments, i.e., 10Be-rich onto 10Be-poor material. Blum et al.’s (1992) analysis of Sr and Nd isotopic ratios points toward Jurassic-Cretaceous sediments, such as those found in abundance in south Laos and east Thailand (Singsoupho et al., 2014). Our point was that Chinese loess, or any other thick Quaternary sedimentary column, cannot account for the consistent 10Be gradient observed from Indochina to Antarctica, interpreted as the translation of a vertical gradient in the target. Mizera put forward instead his previously published (Mizera et al., 2016) target hypothesis in northern China deserts (i.e., the source of Chinese loess dust), and specifically in the Baidan Jaran desert (BJD), using a stack of glacial period sediments (10Be-poor) and interglacial paleosol (10Be-rich).

EURO-CARES (European Curation of Astromaterials Returned from Exploration of Space) was a three year (2015-2017) multinational project funded under the European Commission’s Horizon 2020 research programme. The objective of EURO-CARES was to create a roadmap for the implementation of a European Extra-terrestrial Sample Curation Facility (ESCF) suitable for the curation of samples from all possible return missions, to the Moon, asteroids, Mars, and other bodies of the Solar System. Here we summarize the main recommendations from the final project report for design and infrastructure requirements to allow the curation of samples from restricted bodies such as Mars. Over the course of the project, the team has visited various facilities and companies, to gather best practices, bring innovative ideas, and build a strong network with the international sample curation community. Visits were made to the astromaterials curation facilities of NASA and JAXA, and to related facilities from the nuclear, cleanroom and BSL-4 sectors. Two successful collaborations with architects (Space architecture department of the Technical University of Vienna (Austria), then Merrick and Co. in Kanata (Canada) [1]) resulted in the development of more refined requirements and tentative designs for a Mars Sample Return (MSR) facility. All possible activities that would take place in a MSR facility were first identified. All activities related to receiving, assessing, and opening the Earth Return Capsule are performed in a Sample Receiving Facility. Further activities, such as curation, Sample Early Characterization, andstorage would be performed in a Sample Curation Facility (SCF). The SCF would also include a suite of instruments necessary for analyses defined in a Biohazard Assessment Protocol and for Life Detection. In addition, an Analogue and Mock-Up Facility (to be constructed first) would be used to assemble an analogue material collection, to test instruments and building materials/techniques, and to train staff members. A MSR facility needs to integrate both cleanliness and containment principles, to keep the samples pristine, and to fulfill the Planetary Protection requirement of having a probability of release P

The objective of the H2020-funded EURO-CARES project (grant agreement n° 640190) was to create a roadmap for the implementation of a European Extraterrestrial Sample Curation Facility (ESCF) that would be suitable for the curation of samples from all possible return missions likely over the next few decades, i.e. from the Moon, asteroids and Mars. The return of extraterrestrial samples brought to Earth will require specific storage conditions and handling procedures, in particular for those coming from Mars. For practical reasons and sterility concerns it might be necessary for such a facility to have its own collection of analogue samples permitting the testing of storage conditions, and to develop protocols for sample prepartion and analyses. Within the framework of the EURO-CARES project, we havecreated a list of the different types of samples that would be relevant for such a curation facility. The facility will be used for receiving and opening of the returned sample canisters, as well as for handling and preparation of the returned samples. Furthermore, it will provide some analysis of the returned samples, i.e. early sample characterisation, and is expected to provide longterm storage of the returned samples. Each of these basic functions requires special equipment. Equipment, handling protocols and long-term storage conditions will strongly depend on the characteristics of the materials, and on whether returned samples are from the Moon, Mars or an asteroidal body. Therefore the different types and aspects of analogue samples one need to be considered, i.e. the nature of the materials, which analogues are needed for what purpose, what mass is needed, and how should the analogue samples be stored within the facility. We distinguished five different types of anologue samples: analogue (s.s.), witness plate, voucher specimen, reference sample, and standard. Analogues are materials that have one or more physical or chemical properties similar to Earth-returned extraterrestrial samples. Reference samples are well-characterised materials with known physical and chemical properties used for testing. They may not necessarily be the same materials as the analogues defined above. Standards are internationally recognised, homogeneous materials with known physical and chemical properties that are used for calibration. They can also be used as reference samples in certain circumstances. They may be made of natural materials but are often produced artificially. A voucher specimen is a duplicate of materials used at any stage during sample acquisition, storage, transport, treatment etc., e.g. spacecraft materials (including solar panels), lubricants, glues, gloves, saws, drills, and others. In addition, Earth landing site samples (from the touch down site) would be necessary in case of doubtful analysis, even if normally this type of contamination is not expected. Finally, a witness plate is defined as material left in an area where work is being done to detect any biological, particulate, chemical, and/or organic contamination. It is a spatial and temporal document of what happens in the work area. Analogue materials could be solids (including ices), liquids or gases. These could contain biological (extant and/or exinct) and/or organic components. They could be natural materials, e.g. rocks or minerals, or could be manufactured, such as mixtures of different components, which may be biologically and/or organically doped. Analogues with appropriate sample size and nature will be well-suited for testing and training of sample handling procedures, and for transport protocols. The training of science and curation teams also requires reference samples and standards. Long-term storage needs special witness plates and voucher specimes. Developing and testing sample preparation protocols needs all sample types.

EURO-CARES (European Curation of Astromaterials Returned from Exploration of Space) was a three year (2015-2017), multinational project, funded under the European Commission's Horizon2020 research programme to develop a roadmap for a European Extra-terrestrial Sample Curation Facility (ESCF). Such an ESCF was designed to receive and curate samples returned from Solar System exploration missions to asteroids, Mars, the Moon, and comets. So far, there are only two facilities dedicated for unrestricted returned samples: the NASA Johnson Space Centre in Houston (USA) and the JAXA Hayabusa curation facility in Sagamihara (Japan). Previous studies of an ESCF were either country-specific (e.g., [1]) or mission/target specific (e.g., MarcoPolo-R [2]). With the EURO-CARES project we proposed to move onwards from these specific studies, using experience accumulated at NASA, JAXA, and in various laboratories and museums curating meteorites, in combination with expertise from biosafety laboratories, cleanroom manufacturers, electronics and pharmaceutical companies, nuclear industry, etc. Long-term curation of extra-terrestrial samples requires that the samples are kept as clean as possible to minimize the risk of detrimental contaminants, at the same time ensuring that Martian samples remain contained in case of biohazards. The requirements for a combined high containment and ultraclean facility will naturally lead to the development of a highly specialized and unique facility that will require the development of novel scientific and engineering techniques. We report here a summary of the EUROCARES study.