Dale Andersen’s Astrobiology Antarctic Status Report: 6 December 2022: A Very Busy Week At Lake Untersee
Keith,
We have been fairly busy the last week or so and our weather has been for the most part fairly good. That said, we have 45 knot winds today with poor visibility and whiteout conditions so we are mostly inside of our tents today.
Adam Gaudreau continued GPR (ground penetrating radar) measurements of the perennial ice-cover of Lake Untersee and along the terminus of the Anuchin Glacier which dams the lake. And each time we drill a hole through the ice we measure ice-thickness, the piezometric water level and depth below the hole, adding to our general knowledge of the lake bathymetry.
Denis Lacelle and Andre Pellerin recovered several more sediment cores accross the lake which will be used for pore water analysis, grain size distribution, total organic content and other geochemical measurements. Yesterday Denis retrieved the diffusion samplers that had been deployed early in the season in both basins. These samples will provide us with dissolved gas mesaurements (including the noble gases) at various depths within the water column in both the north and south basins of the lake.
Miles, Andre and I worked with the DeepTrekker Revolution ROV, deploying it into the deepest area of the lake (~165 m) in the north basin and then making another dive hole for it in the south basin and deploying it there between 65 to 92 m. We made a great set of observations at both locations resulting in quite of bit of discussion among us particularly at dinner time when we reviewed video and photos.
Yesterday before the weather started to shift towards the snowy/blowy weather we have today we all hiked within the Aurkjosen Cirque, the small ‘dry valley’ just east of Untersee. Using the Trimble GNSS (GPS) receivers (R12i and R9s), we conducted a survey of the paleoshorelines in the valley as well as measuring points in the lowest locations of the valley.
Several thousand years ago this small dry valley looked much like Lake Untersee – an ice-covered lake with a microbial ecosystem consisting of benthic cyanobacteral mats. Once the Anuchin Glacier retreated, the water supply was removed and over a few hundred years the lake evaporated forming a series of smaller lakes before they all dried completly, leaving only a few physical/chenical traces of their existence in the sedimentary record. The highly accurate elevation measurements made with the Trimble GNNS receivers will allow us tp refine estimates of the volumes of the various lakes that once existed here.
It is clear we will depart Untersee Oasis with a greater understanding of its ecosystem and the events that have shaped its evolution but with many additional interestng questions as well!
Cheers,
Dale
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