Microorganisms found in glaciers, sea ICE and permafrost can remain viable, or even metabolically active, at temperatures well below 0 c. These organisms can live within the salty liquid-vein networks…

This is a $399,873.03 grant for research awarded by the National Aeronautics and Space Administration (NASA) to the Southwest Research Institute (SwRI), a nonprofit research and development organization. The research aims to study extracellular ice binding proteins (IBPs) from cold-tolerant microorganisms found in glaciers, sea ice, and permafrost, and to investigate the detectability of these IBPs using geophysical techniques like ice-penetrating radar and magnetotellurics. The goal is to better understand the microstructural and electrical properties of icy microbial habitats, which could inform the search for similar environments on other planetary bodies like Europa. This research is directly relevant to NASA's Exobiology Program and the Biosignatures area of emphasis. There is no indication that this award has a set-aside designation.

Microorganisms found in glaciers, sea ICE and permafrost can remain viable, or even metabolically active, at temperatures well below 0 c. These organisms can live within the salty liquid-vein networks that exist between ICE crystals. In this proposal, we will study the extracellular ICE binding protein (IBP) that inhibits ICE recrystallization from cold-tolerant microorganisms isolated from the basal ICE of an antarctic ICE core. Similar extant life could exist within warm pockets of europa s ICE shell (chaos terrain). Using magnetic resonance (MR) techniques, we have previously shown that this IBP drastically alters liquid-vein networks within ICE. Using dielectric spectroscopy (DS) measurements, we have previously shown on recrystallized IBP-free ICE that the dielectric properties of ICE are dominated by liquid-vein networks. In this proposal, these two laboratory techniques will conduct measurements on the same samples combining MR diffusion measurements with measurements of the electrical properties for the first time on ICE. MR techniques and simple microscopy conducted at montana state university will provide US with microstructural properties (unfrozen water content, ICE-grain size, surface-area-to-volume-ratio, diameter of liquid veins and tortuosity) and imagery of triple junction liquid networks. DS measurements conducted at southwest research institute in boulder will provide US with broadband complex electrical properties, which can be used to determine the likelihood of a remote geophysical detection of IBP. We will study the detectably of two geophysical techniques (ICE penetrating radar and magnetotellurics) that can measure variations of the electrical properties of europa s ICE shell. This project will constitute the first time that MR techniques and DS have been used together to study the microstructural and electrical properties of an ICY microbial habitat altered by a biosignature (IBP). Our primary objective is to determine the effects of IBP on the microstructural properties of liquid-vein networks within ICE and quantify the impact of IBP alteration upon remotely detectable electrical properties. Therefore, we seek to address the following science questions: (1) what is the threshold IBP concentration within the liquid-vein network needed to impede grain growth? (2) how do ICE s microstructural properties (unfrozen water content, grain diameter, tortuosity), permeability and electrical properties vary with temperature and IBP or salt concentration? (3) can ICE s electrical properties reliably constrain its microstructural properties or permeability? (4) can ICE s microstructural properties be constrained by geophysical techniques? Our approach to solve these questions follows: (1) prepare samples with varying concentrations of salt and IBP. (2) using MR techniques, image and measure the temperature-dependent volume, surface area-to-volume ratio, and tortuosity of liquid-vein networks in lab-frozen ICE samples. (3) using DS, measure the electrical properties of those same samples. (4) develop models relating the dielectric properties of these ICE samples to the MR-derived microstructural properties of the liquid-vein networks. (5) investigate the habitability of vein networks in ICE. (6) as IBP-rich ICE inhibits grain growth IT should decrease the radar attenuation and conductivity. Therefore, we will evaluate the geophysical detectability of IBP-altered microbial habitats. This work is directly relevant to the exobiology program goal to understand the distribution of life in the universe, as we will gain a better understanding of the nature of a microorganism habitat within ICE as well as how easily similar habitats could be detected remotely elsewhere in the solar system. Our proposed research is also relevant to the biosignatures area of emphasis, which supports basic research on the formation and retention of biosignatures under extraterrestrial conditions.