Now, arctic polar scientists have developed a creative solution. Inflating massive balloons under the snow to form surprisingly strong and environmentally friendly cylindrical underground tunnels.
The technique works like making a hot dog, says the method’s pioneer, Jorgen Peder Steffensen, a physicist at the University of Copenhagen. “Using snowblowers we cut a trench that’s the bun,” says Steffensen, who also heads logistics for the East Greenland Ice-core Project (East GRIP).
A research effort focused on understanding the history of the ice sheet. “The balloon is the shape of a giant hot dog, and we inflate it in place below the surface. Then throw snow back on top” the condiments, in this analogy “and the snow hardens on top of that.” Days later, the balloons are deflated and taken away, leaving behind tunnels that provide shelter, workshops, or storage for scientists.
The balloon technique has shown several advantages over the conventional method. First, because of the inherent strength of arches, the cylindrical tunnels contract slightly more slowly than the rectangular shored ceilings. In one test tunnel formed by a balloon, engineers measured a 25-centimeter-per-year contraction. Versus a 27-centimeter-per-year contraction for a traditional trench.
The biggest balloon about 40 meters long
And any contraction easily managed in the cylindrical tunnels. Without shoring in the way. Team members can cut encroaching walls away with saws to rewiden rooms, without risk of collapse. There’s also an environmental advantage. The metal or wood required for the old technique requires fuel-intensive cargo plane flights, and is many times heavier than the balloons. After ceilings deform, the shoring material generally not retrieved from the ice subsurface, and so researchers must leave it behind.
Steffensen first tried the technique in 2012 on another Greenland base. The team that built the full tunnel system at East GRIP. Deploying a total of eight balloons. The biggest balloon 40 meters long. But placed end-to-end to make longer tunnels.
After initial drilling tests last summer, this summer’s drilling has fully begun with the tunnels providing consistently cool temperatures. Polar engineers are interested in adopting the technique elsewhere.