D/H fractionation during sublimation of water ice at low temperatures into a vacuum

The study outlined in this article was carried out within the framework of ESA's PROSPECT programme, which will provide both a sample drill and miniaturised mass spectrometer system for flight on-board the planned Russian Luna-27 mission to the lunar south pole. There, it aims to collect samples of regolith, containing water ice and other volatiles, and to make isotopic and abundance measurements to fingerprint the source(s) of these volatile species. However, it is necessary to first consider how any localised temperature increases during sample acquisition activities may result in water ice loss via sublimation and thus isotopic modification of the remaining residual ice. To attempt to address these concerns, a suite of sublimation experiments was conducted at the Laboratoire de Geologie de Lyon, where a method for performing such experiments was already established (Lecuyer et al., 2017). The results of this work will help to inform modelling which will extrapolate the data down to lunar-relevant conditions.