McMurdo Station is located on a slender peninsula extending from the southern side of Ross Island. At this point in the spring, the sea to the west is covered by a thin crust of first-year sea ice, while to the east the sea lies under the Ross Ice Shelf, a thick layer of freshwater ice amassed of the outflow of glaciers from the surrounding mountains. Standing on the hard-packed snow of the ice sheet, the surface stretches out brilliant white and dead flat.
It was into this featureless expanse that we traveled earlier this week. As a field test, we wanted to leave one of our ozone instruments outside to collect data for a week. We grabbed our lunches, loaded a Pisten Bully snow cat with the ozone instrument, our survival bags and cold weather gear, and hit the road. The Pisten Bully is a hybrid of a diesel pickup truck and a tank. Built on two tracks that run the length of the vehicle, the Bully has the general geometry of a pickup, with a small cab in the front and a cargo area immediately behind. On the Antarctic Bully's, the stock flatbed has been replaced with a heated, window-equipped box to shelter cargo or passengers from the weather. Pisten Bully driver certification is three hours in a classroom (actually a bunch of chairs under a stairway) and a supervised lap around town in a Bully labelled "Student Driver". I had my license and I was ready to roll!!
To protect the tracks of our vehicle from damage, we crept slowly on the gravel road out of town. The route from the rock surface of Ross Island to the snow surface of the ice sheet crosses a rough no-man's land of uneven hummocks and melt ponds called the transition. The slow movement of the ice sheet and the influx of meltwater runoff from the island disrupts this terrain. This crucial link between McMurdo station and the snow runway is closely monitored. A cluster of heavy equipment is stationed at the transition to keep the road passable to the airfield.
On this particular morning, the transition was little match for our Pisten Bully and we emerged onto the ice shelf surface with little problem. With the flat, open expanse of the ice shelf extending to our right, and the ridgeline of the Hut Point Peninsula to our left, we cranked the Bully to speed setting '9', dialed the RPMs to 1700, and made for the junction of the peninsula with the main body of Ross Island. In front of us, bamboo poles stretched out of sight, flagging a crevasse-free route towards Windless Bight.
Windless Bight lies under tucked under the southern slopes of Mount Erebus, a 12,500 ft active volcano. Sheltered by the bulk of this enormous mountain, deep snow had collected at Windless Bight; fighting through the snow, the nose of the Bully rose and the engine tone changed as it came under load. With a low cloud deck hanging 1000 feet off the ground, only the lower reaches of Erebus were visible. Nearing the area where we expected to find the weather station, I climbed up to the roof of the Bully and pulled out my binoculars to scrutinize the ice slopes visible below the clouds. Unlike the smooth ice surface of the shelf, the glaciated slopes of Erebus were torn and split by the flow of ice over rough underlying topography. Where it was split deeply, the slopes showed their glacial blue interior... oops, I was sent up to the roof of the Bully to look for the weather station, not gawk at Erebus. We finally spotted the weather station out in the distance, and installed the test instrument not far from a monitoring site where instruments listen for nuclear explosions, as a means of enforcing the Comprehensive Test Ban Treaty.
With the instrument installed, we flipped the Bully around and followed the bamboo flags back to McMurdo. I hope to get back out to Windless Bight in clear conditons to see the upper slopes of Erebus and its sister peak Mt. Terror.
