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April 11, 2010

GrIT details: GPR team Departs for Survey

GrIT details: GPR team Departs for Survey

The GPR team goes SCAT: Jen, Allan, Robin, Kevin. Photo: Robin Davies

On Thursday, 1 April, the ground-penetrating radar (GPR) survey team–rechristened, perhaps only temporarily, the “Strategic Crevasse Avoidance Technicians,” or SCAT–departed Thule, made their final approach to the transition, and climbed on to the ice sheet to finish flagging a safe route for the first 60 miles of the Greenland Inland Traverse (GrIT) path to Summit. In addition to the instruments and equipment that will enable them to do their jobs, they tow life support: the camping wannigan (a large camp box with kitchen and warm-up facilities), the orange sled, and a fuel bladder on a plastic fuel sled. They have 150 lbs of propane, about 700 gallons of fuel and about a month of food.

The team members are Kevin Emery (GrIT mountaineer), Jen Mercer (CRREL project manager), Allan Delaney (GPR specialist) and Robin Davies (operator and mechanic, with too many other qualifications to list).

On Tuesday, 30 March, while traveling between B3 and B4 waypoints (between 14 and 17 miles from the transition), the team encountered crevasses that were not apparent on the satellite imagery and which had not been encountered during the 2008 GPR survey. One crevasse was estimated to be one meter wide.

Allan checks a GPR record. That's Jen in the front seat. Photo: Robin Davies

The team found three other crevasses in the same area, more evidence of the changeable nature of the ice sheet margins. Kevin Emery used a 2.5 meter probe to explore these crevasses, but could not determine the width of the cracks, though he dug into the snow bridge to gain deeper penetration looking for the void. The team could not find safe passage through this area before returning to Thule to brainstorm with the entire GrIT team for possible solutions to the problem.

The results of their efforts can be seen in the track image below.

The small, light-blue marks are crevasse detection areas; they show the possible strike (the angle the crevasse is running along the hill). The thin, colored lines running quasi-horizontally depict crevasses seen with satellite imagery. The thick black lines show where the GPR team traveled while studying this area. The original route, the Tucker track, is the long, black line running diagonally from upper-mid-left to the lower-right corner. The lower right end of the track is B4, and shows where the team turned around to return to Thule. Image: GrIT team

After consulting with the GrIT team in Thule, we decided to look further south of the original route. On Wednesday, 31 March, the GPR team quickly found a way around the problem area, encountering a crevasse only 16 inches wide. We await good images of the new route, but can say that this change has actually straightened out the line from B2 to B4, decreasing the GrIT route by one mile, per Jen Mercer.

Jen carries flags to be loaded on the sleds. SCAT will probably use many black flags over the next week or so. Photo: Robin Davies

While the GPR team is on the ice, those of us in Thule now begin to focus on the sled mobility tests. More on that soon.—Allen Cornelison

The Greenland Inland Traverse is funded by the National Science Foundation (NSF). CH2M HILL Polar Services and Cold Regions Research and Engineering Laboratories are working together with the NSF to develop the traverse infrastructure and route. The 2010 spring traverse has several foci: find a safe overland route to Summit Station to help reduce logistical costs and environmental impacts of conducting research there; provide a research platform for scientists conducting field work in Greenland; optimize mobility by focusing on the sled/snow interface. For more field notes coverage of GrIT, click here.

GrIT contact:
Jay Burnside, Polar Field Services, CH2M HILL Polar Services
Construction/Operations manager

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