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E307: The dynamics of impact cratering: planetary resurfacing in the laboratory (Lead Supervisor: Jerome Neufeld, BP Institute/DAMTP/Department of Earth Sciences)

Supervisors: Jerome Neufeld (BPI) (DAMTP) (Earth Sciences) and Stuart Dalziel (DAMTP)

Importance of the area of research concerned:

Impact cratering is an important geological process that templates the surface of planetary bodies.  The extent of cratering provides a key method of remotely estimating the age of planetary surfaces, and has been used to estimate the time since tectonics were active on, for example, Mars.  The morphology of impact craters varies between small “simple” craters with roughly parabolic interior profiles, to larger “complex” craters with single or multiple central peaks, flat inner floors, and terraced rims (Melosh & Ivanov, 1999). More recently the presence of lobate deposits on complex Martian craters at high latitudes has been associated with the presence of a glacial substrate (Weiss & Head, 2013).

Project summary:

This project will explore the wide range of observed morphological features through high-speed imaging of the impact of a yield-stress fluid. Yield-stress fluids, such as carbopol, act as a solid until subject to a sufficient stress, after which they flow as a fluid.  In trial experiments, the impact of a droplet of such a fluid relaxes to a series of non-trivial shapes for different impact velocities and sizes, largely mimicking the wide range of phenomena observed in planetary craters.  Understanding the processes that form these different morphologies, and how to model them, will provide valuable insight into the geological process.

What the student will do:

The student will conduct a suite of systematic experiments using a high-speed camera to track the motion of tracer particles in carbopol in order to image deformation during impact and relaxation to the final state.  Profiles of the resulting laboratory craters will be imaged using laser profilometry.  These results will be used to test and inform the development of the models necessary to understand the morphology and genesis of planetary impact craters.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements

References:

Melosh, H.J., Ivanov, B.A. (1999). Impact crater collapse. Ann. Rev. Earth Planet. Sci., 27, 385–415.

Weiss, D.K., Head, J.W. (2013). Formation of double-layered ejecta craters on Mars: A glacial substrate model. Geophys. Res. Lett., 40(15), 3819–3824.

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