Gas containment for in situ sample analysis on the Moon: Utility of sealing materials in the presence of dust

Lunar dust presents a serious challenge to all operations on the Moon, whether human or robotic. It can be especially problematic in applications where it is necessary to make high integrity, gas-tight seals, such as within payloads designed for in situ analysis of lunar ices and volatiles. The challenge has been addressed within the context of the ProSPA instrument being developed for the Luna-27 mission. Soft sealing materials are preferred in order to minimise the required sealing force to enable use of lightweight actuators. JSC-1A simulant was used to test and compare the sealing performance of the elastomer Kalrez® 7075 and of Indium. It was found that both materials were able to seal at dust levels of up to 0.90 mg/cm2 with an applied force of up to 400 N. Indium offers the best sealing performance (better than 10-7 mbar.l.s-1) but Kalrez® is capable of operation at higher temperature, which may be beneficial in applications in which samples are heated to release gases for analysis

PTFE as a viable sealing material for lightweight mass spectrometry ovens in dusty extraterrestrial environments

Ever increasing interest in the Moon, not only for scientific but also commercial and prospecting purposes, requires a more streamlined and reproduceable approach to issues such as the sealing of sample handling ovens, in contrast to the mission-specific mechanisms which have tended to prevail in the past. A test breadboard has been designed and built in order to evaluate the leak rates of different oven sealing concepts and materials within the context of the ProSPA instrument being developed for the European Space Agency. Sealing surface geometries based on a simple 90° knife-edge, and two widely used vacuum fitting standards (VCR® and ConFlat®) have been tested using PTFE gaskets in vacuum across a temperature range of -100°C to 320°C, equivalent to a projected -100°C to 1000°C sample heating range in the ProSPA ovens. The impact of using glass- and carbon- filled PTFE has also been investigated, as has the effect of dust coverage of JSC-1A lunar simulant up to 9 per cent by area. The best combination of properties appears to be unfilled PTFE, compressed between two 90° knife-edges with a confining force of ∼ 400 N. This can produce a leak rates within the 10−7 Pa.m3.s−1 range or better regardless of the level of dust applied within the experimental constraints. A strong temperature-dependence on the leak rate is identified, meaning that careful oven design will be required to minimise the temperature at the seal interface even within the operational temperature range PTFE itself

Insoluble macromolecular organic matter in the Winchcombe meteorite

The Winchcombe meteorite fell on February 28, 2021 in Gloucestershire, United Kingdom. As the most accurately recorded carbonaceous chondrite fall, the Winchcombe meteorite represents an opportunity to link a tangible sample of known chemical constitution to a specific region of the solar system whose chemistry can only be otherwise predicted or observed remotely. Winchcombe is a CM carbonaceous chondrite, a group known for their rich and varied abiotic organic chemistry. The rapid collection of Winchcombe provides an opportunity to study a relatively terrestrial contaminant‐limited meteoritic organic assemblage. The majority of the organic matter in CM chondrites is macromolecular in nature and we have performed nondestructive and destructive analyses of Winchcombe by Raman spectroscopy, online pyrolysis–gas chromatography–mass spectrometry (pyrolysis–GC–MS), and stepped combustion. The Winchcombe pyrolysis products were consistent with a CM chondrite, namely aromatic and polycyclic aromatic hydrocarbons, sulfur‐containing units including thiophenes, oxygen‐containing units such as phenols and furans, and nitrogen‐containing units such as pyridine; many substituted/alkylated forms of these units were also present. The presence of phenols in the online pyrolysis products indicated only limited influence from aqueous alteration, which can deplete the phenol precursors in the macromolecule when aqueous alteration is extensive. Raman spectroscopy and stepped combustion also generated responses consistent with a CM chondrite. The pyrolysis–GC–MS data are likely to reflect the more labile and thermally sensitive portions of the macromolecular materials while the Raman and stepped combustion data will also reflect the more refractory and nonpyrolyzable component; hence, we accessed the complete macromolecular fraction of the recently fallen Winchcombe meteorite and revealed a chemical constitution that is similar to other meteorites of the CM group

Insoluble macromolecular organic matter in the Winchcombe meteorite

The Winchcombe meteorite fell on February 28, 2021 in Gloucestershire, United Kingdom. As the most accurately recorded carbonaceous chondrite fall, the Winchcombe meteorite represents an opportunity to link a tangible sample of known chemical constitution to a specific region of the solar system whose chemistry can only be otherwise predicted or observed remotely. Winchcombe is a CM carbonaceous chondrite, a group known for their rich and varied abiotic organic chemistry. The rapid collection of Winchcombe provides an opportunity to study a relatively terrestrial contaminant‐limited meteoritic organic assemblage. The majority of the organic matter in CM chondrites is macromolecular in nature and we have performed nondestructive and destructive analyses of Winchcombe by Raman spectroscopy, online pyrolysis–gas chromatography–mass spectrometry (pyrolysis–GC–MS), and stepped combustion. The Winchcombe pyrolysis products were consistent with a CM chondrite, namely aromatic and polycyclic aromatic hydrocarbons, sulfur‐containing units including thiophenes, oxygen‐containing units such as phenols and furans, and nitrogen‐containing units such as pyridine; many substituted/alkylated forms of these units were also present. The presence of phenols in the online pyrolysis products indicated only limited influence from aqueous alteration, which can deplete the phenol precursors in the macromolecule when aqueous alteration is extensive. Raman spectroscopy and stepped combustion also generated responses consistent with a CM chondrite. The pyrolysis–GC–MS data are likely to reflect the more labile and thermally sensitive portions of the macromolecular materials while the Raman and stepped combustion data will also reflect the more refractory and nonpyrolyzable component; hence, we accessed the complete macromolecular fraction of the recently fallen Winchcombe meteorite and revealed a chemical constitution that is similar to other meteorites of the CM group