PhD Comprehensive Exam by Peng Lei, ChBE
- Thursday, November 15, 2018 from 3:10pm to 4:00pm
- Roberts Hall, 210 - view map
Investigate Planetary Ice-Regolith Structure with Magnetic Resonance
Abstract: Excess segregated ice has been discovered several times on Mars. A possible formation mechanism “cryosuction” supposes excess ice is formed by migration of the unfrozen water in the system composed by brines, ice-regolith mixtures in the subsurface. To explore the cause of the ice formation, planetary ice structure needs to be investigated. For the Martian analog materials, Magnesium chloride (MgCl2) and magnesium perchloride (Mg(ClO4)2) solutions will be used as the simulated brines due to their abundance on Mars, poly (methyl methacrylate) (PMMA) at different size will be used to simulate the regolith grain on Mars. By using MR techniques, including Carr-Purcell-Meiboom-Gill sequence (CPMG) and Pulsed Gradient Spin Echo(PGSE), the unfrozen water content, surface-to-volume ratio and tortuosity in Martian analog materials can be measured as a function of salt composition, regolith grain size and temperature. Data obtained can be used to predict unfrozen water content and permeability of the ice-regolith mixture to estimate the ice-structure under the various conditions and in advance verify the possible formation mechanism of excess ice on Mars. This seminar will focus on the understanding the unfrozen brine within ice-PMMA mixtures as a function of brine composition, PMMA size and temperature, in order to better understand the recrystallization process in Martian analog materials.
- Department of Chemical and Biological Engineering