Field Notes: The Polar Field Services Newsletter

GrIT Gets Going

Sunrise near Thule Air Base. Photo: Ed Stockard

A team of men and women assembled at Thule Air Base last Wednesday to start preparing for a spring Greenland Inland Traverse (GrIT) expedition to Summit Station. The GrIT effort, a collaboration between the National Science Foundation, Cold Regions Research and Engineering Laboratory (CRREL), and CPS, is aimed at finding a safe route–and an efficient traverse rig–to resupply the NSF’-funded Summit Station on the apex of Greenland’s ice sheet.

We heard from PFS’ GrIT coordinator Allen Cornelison on Friday.  He reported that conditions were “clear, -13F and calm” at the base, though that may have changed by now, of course.

Mechanics Willow Fitzgerald and Robin Davies use a computer to check out the Case tractor. Photos: Allen Cornelison unless otherwise noted.

Testing 1, 2, 3

The GrIT project team at Thule has a variety of activities scheduled before the traverse team actually heads off for Summit.  Allan Delaney, a retired research engineer from Cold Regions Research and Engineering Laboratory (CRREL), will use specialized equipment to find a safe path up through the transition. Other GrIT members will conduct snow strength and sled mobility tests so the cargo rigs that slide toward Summit are the slipperiest possible. And Dartmouth undergraduate student Dave Wantuch is under contract to CRREL to test some robotics software.  We hope to hear from him directly.

Ground-penetrating Radar

Before GrIT heads out, a smaller team will spend about three weeks on a turnaround traverse sounding the transition between land and ice. The ice sheet’s edges are wrinkled and split with crevasses; before the tractors carry the GrIT team out of Thule, we’ll need to know they can maneuver around big crevasses as they climb up on to the ice sheet. Delaney, CRREL’s project engineer Jen Mercer, mountaineer Kevin Emery, and mechanic and equipment operator Robin Davies, will travel the first 60 or so miles of the way, taking ground-penetrating radar (GPR) images of the ice sheet on the lookout for crevasses.

The GPR boom and antenna will be attached to the front of the Tucker.  Davies will drive, and Delaney and Mercer will travel in the cab, watching for crevasse signals on the GPR screen. When they detect a crevasse, Emery, who will be riding a snowmachine behind the Tucker, will probe the crevasse and draw a profile. The team will then flag the crevasse and mark its location using Global Positioning Systems technology.

Allan Delaney sets up the ground-penetrating radar and GPS for the 60-mile crevasse detection effort.

The Tucker will tow a large camping box called a wannigan to serve as a warming hut and kitchen.  But the group will sleep in tents out on the ice sheet. Clearly, GrIT is not for sissies.

Mobility tests

As we’ve described elsewhere, Greenland’s snow conditions have bedeviled the GrIT team, forcing the tractors to pull twice as hard to go half as fast as their counterparts in Antarctica. Tests have suggested poor snow strength in Greenland relative to that found on the southern continent allows the sleds to bog in the snow, which in turn prevents the formation of a super-thin layer of water between the sled and the ice that helps the sled slide along.

While traverse lead Brad Johnson, mechanic/operator Willow Fitzgerald, and carpenter Erik Nichols prepare the basic traverse platform , CRREL’s Jim Lever and Dartmouth’s Dave Wantuch are installing instruments and gear on the fuel sleds that will heat the sled bottom and collect information about how they pull. Lever will lead mobility tests out at the land/ice transition. The testing team will pull sleds with different deck configurations to discover which configuration tracks best while putting the lightest load on the tractors.

Mountaineer Kevin Emery sorts survival gear. He will accompany the crevasse detection team and then ride on the traverse to Summit as well.

When they find the best sled and decking configuration, the team will place fuel bladders on special plastic sleds, fill each with 3,000 gallons of fuel, and head off for the ice cap, picking their way through the crevassed zone with the aid of the markers and GPS information Delaney and team will provide. Though there’s a month to go before we expect the GrIT team to depart Thule, they will need all of that time to optimize their rigs for the haul.

The semi-rigid plastic sleds are left to unroll themselves in the Thule warehouse. These high-tech plastic sheets may be the key to Greenland sled mobility, gliding over the ice sheet. We're about to find out.

In addition to delivering fuel and supplies to Summit, the GrIT team has a full plate in terms of direct science support.  But that’s another story.