Wednesday, March 26, 2014

Strategic Crevasse Avoidance Team



In March 2014, the Strategic Crevasse Avoidance Team (SCAT) surveyed the first treacherous 65 miles of a route the Greenland Inland Traverse (GrIT) will use to resupply the National Science Foundation's Summit Research Station. During a three-week period, the team utilized satellite imagery, Global Positioning Systems, Ground Penetrating Radars, tracked vehicles, and an autonomous robot to ensure a safe and crevasse-free passage.

Satellite Image Showing Crevasses 

Route selection begins by reviewing satellite images taken during previous summers when seasonal snow has melted or ablated and crevasses visible.



These satellite images are then imported into a Geographic Information System (GIS) where crevasses are drawn as colored lines. On the above map green lines represent crevasses visible during the summer of 2013, blue lines during the summer of 2011, and red lines the summer of 2010. The red line represents the 2012 GrIT route.  


GPS Track Logs from GPR Surveys

Potential routes through the crevasse fields are then surveyed with a Ground Penetrating Radar (GPR).



The GPR surveying is primarily done with a Tucker Terra Sno-Cat rigged with a GPR antenna mounted on a 30-foot boom.


"Yeti"

Additional surveys are conducted by an autonomous robot known as Yeti. Mounted with a GPR antenna and recorder, Yeti is able to survey crevassed areas unsafe to travel on with the Tucker Sno-Cat.

A Crevasse as Viewed on a GPR Radar Screen

In the Tucker the imagery is reviewed in real time by highly experienced research scientists from the Cold Regions Research and Engineering Laboratory.


GPR Surveys and Location of Crevasses

The location of crevasses (yellow stars and red lightning bolts) are imported into a GIS and compared with the location of crevasses identified in satellite imagery.



Galen Dossin Profiles a Crevasse

Occasionally smaller crevasses can be safely crossed. To confirm there size, crevasses are profiled using an ice auger and/or a specially developed probe with a heated tip.




The compiled data is reviewed and a GPS route (yellow line) with waypoints (red triangles) created.



GPR Crevasse Survey, Greenland Ice Sheet

The GPS route is exported to aviation GPS mounted in the track vehicles and re-surveyed.



GPS waypoints are marked at each turn and marked with three flags.



Following the route SCAT established, the Greenland Inland Traverse (GrIT) will depart Thule Airbase in early April and spend 30 days traveling 733 miles to Summit Research Station. The fuel and supplies they deliver support the Greenland Environmental Observatory and important research of the changing arctic climate.



In addition to several weeks working out of Thule Air Base, the Strategic Crevasse Avoidance Team spent ten nights in four different camps on the ice sheet. Our living and working space consisted of two heated modules complete with electricity and running water. Temperatures averaged -20 F.


Moving Camp

A Case Tractor assisted with moving our equipment, crew quarters, and supplies. The tractor is one of four that will later be used by GrIT to haul fuel and supplies 733 miles inland to Summit Research Station.


Strategic Crevasse Avoidance Team

SCAT included our mechanic and navigator Robin Davies, radar technician Allan Delaney, mountaineer Galen Dossin, and research scientist Zoe Courville. Not in the above picture is Jim Lever of the Cold Regions Research and Engineering Lab, Jennifer Mercer of the National Science Foundation, Geoff Phillips of Polar Field Services, and myself.





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