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Extreme Shock Pressures: Recovery and Detection of Microfossils.

Yolland, Lawrence (2014) Extreme Shock Pressures: Recovery and Detection of Microfossils. Master of Science by Research (MScRes) thesis, University of Kent,.

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Abstract

In this thesis an experimental method is utilised to test the viability and suitability of algal microfossils in the context of simulating the shock phase of lithopanspermia. Previously, the lunar surface has been suggested as a potential receptacle and store for ejected terrestrial material following a large impact on Earth. This has led to the moon being labelled in the literature as Earth’s attic. A two stage light-gas gun is used in a series of low velocity and hy pervelocity impacts. These shot range from 0.388 to 5.11 km s-1. These impact velocities experimentally map to computer simulations of ejecta originating from Earth and impacting the lunar surface. Here microfossils are loaded into a sabot and frozen. They are then fired using the light-gas gun at pre-defined velocities at a water bag target. Following the impact the water is filtered and the filtrate analysed under a scanning electron microscope. This thesis finds a shock pressure related size effect in terms of a number of size metrics. Peak shock pressure is calculated using the Planar Impact Approximation. With this, the maximum shock pressure induced by an impact was calculated to be 13.3 GPa. Microfossil fragments were recovered following each shot but intact examples became rarer as the shot velocity was ramped up. This study also provides a solution to a methodological problem arising from evacuation of a light-gas gun, and the consequential evaporation of liquids within a sabot. Thus a projectile design that can contain liquid at low pressure is made available here.

Item Type: Thesis (Master of Science by Research (MScRes))
Uncontrolled keywords: Astrobiology Biomarker Impact
Subjects: Q Science > QB Astronomy
Divisions: Faculties > Sciences > School of Physical Sciences
Depositing User: Users 1 not found.
Date Deposited: 12 Oct 2015 11:00 UTC
Last Modified: 29 May 2019 16:07 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50878 (The current URI for this page, for reference purposes)
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