22 May 2016
To prepare for the GrIT’s return to Thule, four CPS staff flew to Thule Air Base last week to open traverse infrastructure. Spring has arrived at the airbase: temperatures ranged from 27F to 40F, with a few days of light, quickly melting snow. The sun’s rays assist with drying out the thick, sticky mud in Thule’s work spaces, but it is unwelcome at the transition where snow disappears all too quickly. The CPS team inspected the transition and found good news: the snow fence erected in April had caught a large drift; despite the melting around Thule, the transition snow seems to be holding. Having enough snow to create a surface for the tractors and sleds to use to drive off the ice sheet is crucial to returning the vehicles to their parking area on land.
Out on the ice, the GrIT has traveled over 200 miles since departing Summit on 15 May. Lighter loads and a packed road (established during the run to Summit) has enabled the tractors to move at speeds of 6-7mph on average, with a few 60+ mile days clocked. Unfortunately, mechanical issues hamper progress.
A plastic valve cover melted due to proximity to the heat of the tractor turbo, so the mechanics had to rebuild the cover with epoxy and high temperature silicone and then let it cure overnight. In addition, they removed the steel plates between the turbo and the valve cover and inserted a layer of ceramic glass insulation to keep the compartment cool.
Coinciding with the valve cover repair, the steel towing cable on the crew quarters module broke, having weakened where it was chaffing against the u-bolts. The crew replaced it with a dynema rope, fitting it with as much anti-chaffing protection as possible.
In addition, the left rear inside idler wheel bearings collapsed on the Case 500. These tractors run with two idler wheels on the rear track, so the GrIT continued for several days with just one idler—until it failed as well. The idler’s location on the inside meant that in order to repair it, the mechanics would have to remove the track, a very difficult job in the field. Instead, the GrIT crew placed the inside idler from the right side track on the left side, leaving both tracks to run on just one idler. To accommodate the 500’s reduced pulling capacity, our team distributed its cargo to the two fully functioning tractors.
Our team is excited to get back to Thule. Despite the setbacks (e.g., 2 days stopped to repair vehicles), the crews are still moving forward. Daily chores abound, including chipping out the ice, checking the cargo and refueling tractors daily (as seen in the photo below).
The Arctic Research Support and Logistics Program within the National Science Foundation’s Division of Polar Programs funds the GrIT. CH2MHILL Polar Services and Cold Regions Research and Engineering Laboratories are working together with the NSF to develop the traverse infrastructure and route to Summit Station. The 2016 spring traverse delivers cargo to Summit Station, and continues efforts to optimize mobility, GrIT will provide direct science support to several projects, retrieving instruments for a soon-to-be-completed effort, and laying fuel caches for upcoming projects. Follow GrIT’s progress here: http://datatransport.org/grit.