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

Assessment of the performance and radiation damage effects under cryogenic temperatures of a P-channel CCD204s

CCDs continue to be the detector of choice for high resolution and high performance space applications. One perceived drawback is their susceptibility to radiation damage, in particular the formation of trap sites leading to a decrease in charge transfer efficiency. To that end, ESA has started a programme to investigate a new generation of devices based upon p-channel technology. The expectation is that once mature, p-channel devices may offer a significant increase in tolerance to proton radiation over traditional n-type buried channel CCDs. Early studies of e2v devices to assess the radiation hardness of p-channel devices were limited by the quality of devices available, however more recently, good quality p-channel CCD204s have been manufactured and studied. A more detailed evaluation of p-channel CCDs is now underway to realise the full potential of the technology for use in future high radiation environment space missions. A key aspect is the development of a cryogenic test rig that will allow for the first time a direct comparison of the radiation damage effects when the irradiation is performed both traditionally unbiased at room temperature and cryogenically with the device operational. Subsequent characterisations will also be performed on the cryogenic device after periods of storage at room temperature to investigate the potential annealing effects upon the lattice damage. Here we describe and present early results from an extensive programme of testing which will address all key performance parameters for p-channel CCDs, such as full electro-optical characterisation, assessment of radiation hardness and investigation of trap species

A primordial noble gas component discovered in the Ryugu asteroid and its implications

Ryugu is the C-type asteroid from which material was brought to Earth by the Hayabusa2 mission. A number of individual grains and fine-grained samples analysed so far for noble gases have indicated that solar wind and planetary (known as P1) noble gases are present in Ryugu samples with concentrations higher than those observed in CIs, suggesting the former to be more primitive compared to the latter. Here we present results of analyses of three fine-grained samples from Ryugu, in one of which Xe concentration is an order of magnitude higher than determined so far in other samples from Ryugu. Isotopically, this Xe resembles P1, but with a much stronger isotopic fractionation relative to solar wind and significantly lower 36Ar/132Xe ratio than in P1. This previously unknown primordial noble gas component (here termed P7) provides clues to constrain how the solar composition was fractionated to form the planetary components