Polar Notes

Feb 2017

Is Halley VI secure?

In 2013, satellite data revealed that a long-dormant chasm in the Brunt Ice Shelf had begun to grow again. That crack, pressing northwards at a rate of about 1.7km per year, threatened to cut the British Antarctic Survey’s (BAS) Halley VI research station (primarily used for global earth, atmospheric and space weather observation in a climate sensitive zone) adrift from the rest of the inland ice shelf, with no means of recovering it.  

Yet Halley VI, which was opened in 2012, was designed with such a contingency in mind. As the world’s first re-locatable research facility, the £22 million station (which won awards for its design) comprises eight inter-linked pods resting on hydraulic legs and skis. The pods can be pulled apart and then towed to a new location. In the 2015/16 austral summer, BAS took the decision – for the first time – to move Halley VI 23km across the ice, and away from the spreading chasm.  

The operation to decouple the station and move it to its new location started last autumn, at the beginning of the 2016/17 austral summer. The whole operation lasted twenty weeks and finished ahead of schedule. A team of 70 was involved on site, with further support provided from BAS’ home in Cambridge and several other contractors. Given the complexities involved, the fact that the station is should be ready for use at the end of 2017 represents a remarkable success, not least because some of those working on the site were spending their first season in Antarctica.    

However, in January, while Halley VI was being moved, concerns grew about another crack that had been detected in the Brunt Ice Shelf a few months earlier, this time c. 17km north of the research station. The new crack, which had grown rapidly since it was first detected in October, threatened to trigger a calving event that could destabilise the rest of the ice shelf, including the area used to support austral winter relief operations from the sea.  

While the new crack did not immediately threaten Halley VI itself (or the operation to relocate), glaciologists were not able to predict, with certainty, whether a natural calving event would occur in 2017/2018, or what stresses and strains that would put on the remaining shelf (posing a major risk to BAS’ ability to carry out relief operations during the winter).  

BAS therefore took the precautionary decision of closing the research station for the winter. Given that an average winter at Halley VI sees temperatures drop below -20°C (falling as far as -55°C) and 24-hour darkness over a period of 105 days, the risk of scientists (sixteen of which were due to remain through the winter) being cut off from help was deemed too great to bear.  

Halley VI, then, in its new location, is secure for now. However, glaciologists remain uncertain about the long-term stability of the ice shelf and will continue to watch how the cracks behave over coming seasons. Meanwhile, BAS is focussed on ensuring that the station is ready for re-occupation ahead of the next austral summer. The last personnel will leave in March and plan to return in November. In the meantime, several data collection systems will continue to run autonomously over the Antarctic winter.

Map of Halley VI relocation

Press release from the British Antarctic Survey: