Details of Award
NERC Reference : NE/V014129/1
The consequences of the Moon-forming impact for the chemistry of Earth
Fellowship Award
- Fellow:
- Dr S J Lock, University of Bristol, Earth Sciences
- Grant held at:
- University of Bristol, Earth Sciences
- Science Area:
- Earth
- Overall Classification:
- Panel A
- ENRIs:
- Global Change
- Natural Resource Management
- Science Topics:
- Deep mantle processes
- Earth history
- Extreme pressures
- Extreme temperatures
- Geochemistry
- Geodynamics
- Mantle composition
- Siderophile elements
- Mantle & Core Processes
- Earth history
- Extreme pressures
- Extreme temperatures
- Geochemistry
- Geophysics
- Mantle composition
- Siderophile elements
- Planetary Surfaces & Geology
- Abstract:
- At the very end of its growth, Earth was hit by another planet-sized body that spewed material into orbit, out of which the Moon formed. This collision, known as the Moon-forming giant impact, had a catastrophic effect on Earth. It blew material off into space, melted and vaporised substantial fractions of the rocky portion of the planet (inflating Earth to many times its current size), and left Earth spinning rapidly, with a day as short as 2.3 hours. In our solar system, such a catastrophic final event is thought to be unique to Earth, and the Moon-forming impact played a crucial role in dictating Earth's properties and subsequent evolution. How Earth acquired its unique atmosphere and oceans is a fundamental, unanswered question. It is thought that Earth had gained a lot of its volatiles (such as water, nitrogen and carbon) before the Moon-forming impact. However, the Moon-forming impact likely kicked off a substantial fraction of the atmospheres and oceans of the colliding bodies. As a result, the modern Earth only inherited a fraction of the volatiles it had before the impact, but how large a fraction is uncertain. After the impact, all of Earth's volatiles were mixed together in the mess of rock liquid and vapour that was the post-impact Earth, and there were no separate atmosphere or ocean layers. It took thousands of years for Earth to cool enough for the atmosphere to emerge, and much longer before the oceans started to rain out. During this time, and for millions of years afterwards, Earth was bombarded by smaller rocky and icy bodies. A good fraction of these bodies were the debris from the Moon-forming impact. These small bodies could have delivered volatiles to Earth, but they could have also blown more of its atmosphere into space. A lot of these processes are poorly understood, and we do not yet know how the Moon-forming impact, and the chain of events it triggered, shaped Earth's atmosphere and oceans. This project will explore how the Moon-forming impact changed the chemistry of Earth, particularly its inventory of volatile elements. I will focus on identifying key observations that can be used to test different proposed scenarios and so teach us more about the history of our planet. Many attempts have been made to calculate the amount of atmosphere and ocean that survived the Moon-forming impact. However, previous studies do not include two key things that affected how much of the atmosphere and ocean was lost. First, the colliding bodies were likely spinning rapidly, making it easier for atmosphere to be lost. Secondly, as the bodies were drawn together, the gravitational influence of each distorted the oceans and atmospheres of the other which may have made it harder or easier for volatiles to be lost. I will use sophisticated computer simulations to calculate what fraction of the atmosphere and ocean were lost during the impact, including these two important effects. I will also explore how the atmosphere of Earth emerged after the impact, a hitherto largely unexplored stage in Earth's evolution. I will calculate how the structure of Earth evolved over time and how volatiles were spread throughout the planet and atmosphere. I will determine the mass and chemistry of Earth's atmosphere at the very start of its history, setting the stage for Earth's subsequent evolution and the emergence and persistence of life. Finally, I will explore what happened to the material that was blown off during the Moon-forming impact and how it influenced Earth's chemistry. I will determine the size and velocity of the material that was ejected during the impact, and then calculate how that material was swept up by different bodies in the solar system. Crucially, I will include the changing size and shape of Earth as it cooled, something that previous studies did not. By finding out when, and how many, bodies fall back to Earth, I can determine whether impact debris added to or depleted Earth's atmosphere.
- NERC Reference:
- NE/V014129/1
- Grant Stage:
- Awaiting Event/Action
- Scheme:
- Research Fellowship
- Grant Status:
- Active
- Programme:
- IRF
This fellowship award has a total value of £606,491
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DI - Staff | DA - Estate Costs | DI - T&S | DA - Other Directly Allocated |
|---|---|---|---|---|---|
| £21,096 | £253,181 | £260,140 | £48,338 | £21,367 | £2,368 |
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