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The implications of large asteroid break-ups for (exo-)Earth climate and habitability
Lead Supervisor: Mark Wyatt, Institute of Astronomy
Co-supervisor: Oliver Shorttle, Department of Earth Sciences, Institute of Astronomy; Alex Archibald, Department of Chemistry

Brief summary
This project will determine how the break-up of large asteroids influences the conditions on nearby planets and consider the consequences for their habitability. Such break-ups create objects with sizes from large boulders down to dust, which then undergo dynamical evolution, some of which then being accreted. That accretion in turn influences the planet’s atmosphere and affects its climate. This project will model both these processes – the evolution of the debris field and the effect on the atmosphere – as well as how such events may be evident in the geological record, and their consequence for habitability.
Importance of the area of research concerned
The evolution of life on Earth has been strongly influenced by interaction with exogenous material from elsewhere in the Solar system – that is, asteroids, comets and dust in the zodiacal cloud. For example, the mid-Ordovician ice age has been linked to dust accreted following the break-up of a large asteroid and the extinction of the dinosaurs to an impact event. The accretion of this dust by the Earth, and its bombardment by larger bodies, was even more intense early on when life would have been developing, as evidenced by cratering on the Moon. The bright exozodiacal dust disks found around nearby particularly young stars show that these processes must also be occurring on exoplanets. It is thus important to determine the effect that this delivery of exogenous material may have had on the conditions on potentially habitable planets, and so its effect on the development and evolution of life.

What will the student do?
The project has 4 objectives: (1) develop a model with 3 distinct interdisciplinary components: (i) a dynamical model for the delivery to a planet of dust and asteroid-sized fragments following a collision, (ii) consider geological processes for the potential to recognise such events in the geological record, (iii) model how the planet’s climate is affected by accretion of this material. (2) Apply this to the asteroid break-up linked to both of the Earth’s geological record and climate to constrain any free parameters and to consider the viability of ice age triggering. (3) Consider how asteroid break-ups would have affected the Earth’s climate and geological record throughout its entire history, including the intense bombardment of early times. (4) Consider the implications of asteroid break-ups in extrasolar systems on their habitable plane

Archibald et al., 2020, GMD, 13, 1223
Schmitz et al. 2019, Sci. Adv., 5, 9, eaax4184
Rigley & Wyatt 2020, MNRAS, 497, 1143

Requirements as to the educational background of candidates that would be suitable for the project
For such an interdisciplinary project it is very unlikely to find a student with experience in all aspects of the project. The project would be suitable for a mathematically and numerically strong Earth Science or Atmospheric Chemistry student, or for an (Astro)physics student with broad interests/background.

You can find out about applying for this project on the Leverhulme Centre for Life in the Universe widening participation PhD Studentships page.