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Biography

Professional biography

2023- present: Senior Lecturer, AstrobiologyOU, School of Environment, Earth and Ecosystem Sciences, Open University

2023: Senior Research Fellow, AstrobiologyOU, Open University

2020-2023: Research Fellow, AstrobiologyOU, Open University

2016-2019: Postdoctoral Research Fellow, School of Earth and Environmental Sciences, University of St Andrews

2016: Research Assistant, School of Earth and Environmental Sciences, University of St Andrews

2012-2016: PhD in Astrobiology, School of Physics and Astronomy, University of Edinburgh

Research interests

My research interests centre around icy worlds in our Solar System that contain liquid water under their surfaces. These so-called 'ocean worlds' that include Jupiter's moons Europa and Ganymede, Saturn's moons Titan and Enceladus, and dwarf planets such as Ceres, may contain conditions suitable for life in the present day. I focus on how ice and salts delivered to the surfaces of these worlds by processes such as 'cryovolcanism' can be used to learn about the oceans far below.

Work in my team involves laboratory experiments and fieldwork to icy world analogue locations in Earth's high latitudes. We seek to understand how ocean chemistry and evidence of life might become delivered to and preserved at the surfaces of icy worlds. A major focus is on how the physical conditions in cryovolcanic eruptions (such as the extreme changes in temperature and pressure in the plumes of Enceladus) affects the erupted material. 

In the lab, we develop and employ novel cryo-analytical techniques to understand icy world materials at the molecular and micro-scale, and use planetary simulation facilities to relate our findings to the icy surfaces of ocean worlds. In the field, we study ice, brines and aerosols ejected from the subsurface in polar and sub-polar environments, including in Iceland, Svalbard and the Canadian High Arctic. Our findings help interpret existing data from missions such as Galileo and Cassini, and support upcoming missions such as the JUpiter Icy Moons Explorer (ESA) and the Europa Clipper (NASA). 

 

Recent research highlights

1. My team has discovered a new type of salt crystal, made from sodium chloride and water molecules, that forms during rapid 'flash' freezing of brines. This is only the third new form of sodium chloride to be described in over 200 years. In a recent paper led by OU postdoctoral researcher Dr Rachael Hamp, we describe the structure of this material and how it relates to other known forms of sodium chloride. If detected by upcoming missions at icy worlds it would indicate regions where liquid from below has been rapidly delivered to the surface by active process such as plumes. 

2. We have developed new experimental and analytical techniques to study on the microscale how salty fluids behave as they freeze. We have used these approaches to identify the likely composition of ice grains emmitted in the plumes of Enceladus, and track how evidence of life might be captured or preserved within them. 

3. I have identifed Europa 'analogue' locations in the Canadian High Arctic, where supercold brines seep out to the surface, and form salts with similar chemical composition to those observed at Europa. This work has led to an extended research programme, with a range of talented UK and international colleagues, tracking how chemical and molecular traces of microbial life are preserved within the salts. This work helps to build the rationale for future missions that aim to directly seek evidence of life at icy worlds.

4. Working with an international team, we explored how liquid brines could be distributed vertically within Europa’s ice shell, and showed how this distribution affects the prospects for life within the ice. This work helps us to predict the depth at which habitable environments may be found in the present day, and has implications for protecting Europa from any Earthly contamination we might inadvertently bring on future spacecraft.

Publications

Journal Article

A Potential Mushy Source for the Geysers of Enceladus and Other Icy Satellites (2025)

Small amounts of dissolved salts increase the mobility of mud flows on Mars and other extraterrestrial bodies (2025)

Is there H2O stacking disordered ice I in the Solar System? (2024)

Molecular biosignatures in planetary analogue salts: implications for transport of organics in sulfate-rich brines beyond Earth (2024)

Metastable Dihydrate of Sodium Chloride at Ambient Pressure (2024)

Iron reduction as a viable metabolic pathway in Enceladus' ocean (2023)

Brine Volume Fraction as a Habitability Metric for Europa's Ice Shell (2022)

Compositional Controls on the Distribution of Brine in Europa’s Ice Shell (2022)

Sulfur Cycling as a Viable Metabolism under Simulated Noachian/Hesperian Chemistries (2022)

Sulfur isotopes as biosignatures for Mars and Europa exploration (2022)

Hunting for Life on Mars by Studying Life on Earth (2021)

Quadruple sulfur isotope biosignatures from terrestrial Mars analogue systems (2021)

Volcanic controls on the microbial habitability of Mars‐analogue hydrothermal environments (2021)

Partitioning of Crystalline and Amorphous Phases During Freezing of Simulated Enceladus Ocean Fluids (2021)

The identification of sulfide oxidation as a potential metabolism driving primary production on late Noachian Mars (2020)

Natural Analogue Constraints on Europa's Non-ice surface Material (2019)

An Ionic Limit to Life in the Deep Subsurface (2019)

Cryogenic silicification of microorganisms in hydrothermal fluids (2018)

Building a Geochemical View of Microbial Salt Tolerance: Halophilic Adaptation of Marinococcus in a Natural Magnesium Sulfate Brine (2018)

Ionic strength is a barrier to the habitability of Mars (2016)

Multiplication of microbes below 0.690 water activity: implications for terrestrial and extraterrestrial life (2015)

Presentation / Conference

Freezing behaviour of water droplets at the liquid-vacuum interface relevant to plume-forming regions on Enceladus (2024)

Composition and Habitability of Europa’s Ocean Over Time (2024)

Microstructure controls longevity of exposed salt-rich ices on icy worlds (2024)

Composition and Habitability of Europa’s Ocean Over Time (2024)

Salt-Ice Grain Formation in the Enceladus Plume: A Combined Experimental and Remote Sensing Approach (2024)

Bubbles are rockets for microbes: predicting microbial dispersion in Enceladus’s plumes based on bubbling in Iceland’s geothermal springs. (2024)

Composition and Habitability of Europa’s Ocean Through Time (2023)

Insights into the origins and composition of cryovolcanic plume particles from natural and experimental analogues (2023)

Modelling possible chemical evolution pathways during crystallisation and re-mobilisation of brines in Europa’s ice shell (2023)

Geochemistry and microbiology of geothermal aerosols in Iceland: implications for biosignatures in the plumes of Enceladus (2023)

Geochemistry and microbiology of geothermal aerosols in Iceland: implications for biosignatures in the plumes of Enceladus (2023)

Modelling possible chemical evolution pathways during freezing of Europa’s ice shell (2023)

Entombment of microorganisms within rapidly frozen fluid droplets relevant to the plumes of Enceladus (2022)

Experimentally probing the origin of Enceladus’s plume: bubble-bursting and aerosol formation at the liquid/vapour interface (2022)

Entombment of microbial biomass within rapidly frozen fluid droplets relevant to the plumes of Enceladus (2022)

Modelling water-rock interactions in the subsurface environment of Enceladus (2021)

Brine evolution and transport-driven fractionation of ocean fluids within Europa’s icy shell (2021)

Colour Peak:An analogue environment for the waters of late Noachian Mars (2020)

Cryovolcanic plumes as a record of habitability: Fluid evolution and the fate of bioessential elements during freezing of simulated Enceladus ocean brines (2020)

The identification of sulfide oxidation as potential metabolism driving primary production on late Noachian Mars (2020)

Colour Peak: An analogue environment for late Noachian Mars (2020)

Chemical fractionation in terrestrial geysers: implications for cryovolcanic plumes at ocean worlds