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Project Progress

As part of the Indiana-Princeton-Tennessee Astrobiology Initiative, investigating physical and chemical limitations of life on earth with potential application for life-detecting strategies on Mars, Barry Freifeld at the Lawrence Berkeley National Lab designed and constructed a borehole sampling device intended for installation at the High Lake project site (67°22’N, 110°50’W). This device will allow for long-term sampling of geofluids (gas and water) and microbes in an extreme groundwater environment. Samples will be collected and moved to the surface via a U-shaped tube integrated with a downhole check valve that admits fluid into a loop of 6.4 mm diameter stainless steel tubing. Compressed nitrogen gas at the surface closes the check valve and forces the aliquot of fluid caught in the bottom of the tubing up to the surface. The U-tube is wrapped with a heat trace, consisting of direct burial 14 gauge wire that provides 21 watts/meter of heating along the length of the sampling lines to prevent freezing in the permafrost zone. Using a pressure/temperature sensor co-located with the U-tube inlet, it is possible to record the pressure transient during each sampling event. A multimode fiber-optic cable will be installed adjacent to the U-tube in order to collect distributed temperature sensor measurements along the length of the borehole. When data from the distributed temperature sensor is coupled with the heat trace, in situ estimates for thermal conductivity and geothermal heat-flux can be derived.

Videographer Peter Suchecki visited Lawrence Berkeley National Laboratory during construction of the U-tube device and documented assembly of the sampling, heating, and temperature monitoring components. Interviews were conducted with Barry Freifeld for use in education and public outreach aimed at illustrating how scientists imagine and engineer instruments for remote installations on Earth and other planetary bodies.

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