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A slow-cooling-rate in situ cell for long-duration studies of mineral precipitation in cold aqueous environments on Earth and other planetary bodies

DOI: 10.1107/S1600576718008816 DOI Help

Authors: Stephen P. Thompson (Diamond Light Source) , Hilary Kennedy (Bangor University) , Sarah Day (Diamond Light Source) , Annabelle R. Baker (Diamond Light Source) , Benjamin M. Butler (Bangor University) , Emmal Safi (Diamond Lighty Source; Keele University) , Jon Kelly (Diamond Light Source) , Andrew Male (Diamond Light Source) , Jonathan Potter (Diamond Light Source) , Tom Cobb (Diamond Light Source) , Claire A. Murray (Diamond Light Source) , Chiu C. Tang (Diamond Light Source) , Aneurin Evans (Keele University) , Ronaldo Mercado (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Applied Crystallography , VOL 51 , PAGES 1197 - 1210

State: Published (Approved)
Published: August 2018
Diamond Proposal Number(s): 10025

Open Access Open Access

Abstract: Liquid oceans and ice caps, along with ice crusts, have long been considered defining features of the Earth, but space missions and observations have shown that they are in fact common features among many of the solar system's outer planets and their satellites. Interactions with rock-forming materials have produced saline oceans not dissimilar in many respects to those on Earth, where mineral precipitation within frozen seawater plays a significant role in both determining global properties and regulating the environment in which a complex ecosystem of extremophiles exists. Since water is considered an essential ingredient for life, the presence of oceans and ice on other solar system bodies is of great astrobiological interest. However, the details surrounding mineral precipitation in freezing environments are still poorly constrained, owing to the difficulties of sampling and ex situ preservation for laboratory analysis, meaning that predictive models have limited empirical underpinnings. To address this, the design and performance characterization of a transmission-geometry sample cell for use in long-duration synchrotron X-ray powder diffraction studies of in situ mineral precipitation from aqueous ice–brine systems are presented. The cell is capable of very slow cooling rates (e.g. 0.3°C per day or less), and its performance is demonstrated with the results from a year-long study of the precipitation of the hydrated magnesium sulfate phase meridianiite (MgSO4·11H2O) from the MgSO4–H2O system. Evidence from the Mars Rover mission suggests that this hydrated phase is widespread on the present-day surface of Mars. However, as well as the predicted hexagonal ice and meridianiite phases, an additional hydrated sulfate phase and a disordered phase are observed.

Journal Keywords: long-duration studies; mineral precipitation; cold aqueous environments; terrestrial minerals; planetary minerals; planetary ices; solar system

Subject Areas: Earth Science, Chemistry

Instruments: I11-High Resolution Powder Diffraction