Investigating aqueous and thermal alteration in carbonaceous chondrite meteorites

Summary

Primitive asteroids are the debris left over from planet formation. They are rocky time capsules that record the earliest conditions in the protoplanetary disk, and are important tracers for the processes and events that have shaped our solar system over the last ~4.5 billion years.

Two space missions, NASA's OSIRIS-REx and JAXA's Hyabusa2, are characterising of the physical and chemical properties of the primitive asteroids Bennu and Ryugu, with the aim of returning to Earth with samples collected from the surface.

We can also learn about asteroids by studying meteorites in the laboratory. The chemical composition, mineralogy and textures found within meteorites enable us to reconstruct the geological history of asteroids. The aqueously altered CI, CM and CR carbonaceous chondrite meteorites are derived from water-rich asteroids, a possible source of extra-terrestrial H₂O and organics to the Earth.

A small number of CI, CM and CR chondrites also underwent thermal metamorphism and may be good analogues for the types of materials that will be encountered on the surface of asteroids Bennu and Ryugu. However, disentangling the effects of both hydration and heating is challenging and important questions still remain regarding the cause, timing and duration of the alteration.

The aim of this project is to investigate the mineralogical, textural and chemical properties of the thermally altered CI, CM and CR chondrites.

Methodology and training

The project has the potential to use a wide range of analytical techniques including optical and electron microscopes (SEM/EMPA), computed tomography (CT) scanning methods, and Raman spectroscopy. Isotopic measurements will be used to infer the timing of alteration, and dynamic heating experiments will constrain the mineralogical and chemical changes associated with thermal metamorphism.

The results of the project will provide new insights into the evolution of asteroids and a framework for understanding samples returned from asteroids Bennu and Ryugu.

This is a multi-disciplinary project utilising the world-class meteorite collection and analytical facilities available to the Planetary Materials Group at the Natural History Museum, London, the Isotope Geochemistry and Cosmochemistry Group at the University of Manchester, and the Planetary and Space Science Group at the Open University.

The project would suit an enthusiastic individual with a keen interest in planetary science, and a strong background in the geosciences.

Eligibility

Projects are funded for 3.5 years as an STFC studentship, which will cover all fees and a student stipend if you are from the UK, or from the EU and meet residency requirements (settled status, or 3 years full-time residency in the UK). For full details on what is covered by the studentship please see the STFC guidance.

For informal enquiries or further information, please contact Dr Paul Schofield, Dr Rhian Jones or Dr Ashley King.

How to apply

Deadline: Friday 28 February 2020

Please send the following documents to Anna Hutson at postgradoffice@nhm.ac.uk

• Curriculum vitae
• Covering letter outlining your interest in the PhD project, relevant skills training, experience and qualifications, and a statement of how this PhD project fits your career development plans.
• Transcripts of undergraduate and Masters’ degree results.
• Two academic references including (if applicable) Masters’ project supervisor.

Interview date: March 2020

Start date:          October 2020