Ice station on the edge of the abyss

Rescue mission under way for Antarctic research base standing in fissure’s path.

 

Halley VI Research Station is 8km from the growing crack. Photo / Nasa

It has all the hallmarks of a Hollywood disaster movie.
A crack along the Antarctic ice-shelf is making its way towards an isolated research station, threatening to plunge the scientists on board into the frozen seas.
As the fissure moves ever closer, scientists at headquarters mount a desperate rescue mission.
The grim scenario is all too real for the 35 men and women stationed on Halley VI.
The British Antarctic Survey (BAS) research station, which opened in 2013, is located on the Brunt ice shelf, a floating slab of ice up to 250m thick attached to the Antarctic landmass and extending out into the sea.
The station's eight space-age modules are under threat from an ice crack called Chasm 1, a massive fissure more than 49m deep, 29km long and almost 1km wide.

Chasm 1 was dormant until 2012, when satellite measurements confirmed it had started to grow. Worse still, it was discovered the crack is extending in the direction of Halley VI at a rate of 1.5km a year and is now just 8km from the base.
An operation has now been launched to move the base before the situation reaches a point of no return - such as a huge chunk of ice breaking off, in a process known as glacial "calving", with the ice-station stranded on top of it.
Hilmar Gudmundsson, a glaciologist with the BAS, said: "We don't know what will happen. It might stop growing, but we can't exclude the possibility of a big calving event."
Taking advantage of the Antarctic summer, which follows nine months of winter isolation, preparations are now in hand to move Halley VI.
In the months ahead, bulldozers will be brought in by ship to tow the modules to a new location, about 30km away from Chasm 1. The operation is expected to be completed in a year's time.
Adam Bradley, Halley's station leader, warns that even small slopes could pose an insurmountable obstacle in moving the heavy modules and a route will have to be carefully plotted before the operation begins.
"One of the jobs is to define the maximum slope we can tow these things up," said Mr Bradley.
All five of Halley VI's predecessors have been abandoned after becoming buried in snow, so the danger to its continued operation is all too real.
Crevasses and chasms are a common feature of ice-shelves, and large cracks can form, leading to huge icebergs breaking off the main shelf into the sea.
This occurred in 1998, when a section of the Antarctic's Filchner-Ronne ice-shelf measuring 145km by 50km broke away, carrying with it a then unoccupied German research station. Two years ago an iceberg the size of New York broke off the Pine Island Glacier.
"All ice shelves do this. It's a natural event," said Dr Gudmundsson. "But it's difficult to say exactly when and how large these events will be. It's like trying to predict an earthquake."

On cracking ice

• Halley VI, British Antarctic Survey research station.
• Opened in 2013.
• Features eight space-age modules.
• On the Brunt ice shelf - a 250km thick slab attached to the Antarctic landmass.
• At risk from a 29km long crack in the ice.