Monday 11 July 2005
Halley 1 to 5
Pretty soon the winner of the design competition to build a new Halley base will be decided. It will be the sixth research station built on the Brunt Ice Shelf and is designed to replace the current base. Once the new station is up and running, Halley V will be completely dismantled in order to comply with the strict environmental rules of the Antarctic Treaty.
I'll write about the winning design once it's been announced, but for now I thought I'd talk a bit about why we've ended up building a new base roughly every 10 years.
The original Halley base was first occupied in 1956 for the International Geophysical Year. It was a simple wooden hut similar to those used by the early explorers and so was quickly buried and crushed by the ice. Additional buildings were added creating a multilevel complex that was eventually abandoned after 11 years. By that time Halley II was partially operational but unfortunately the new building was even less successful and had to be abandoned on safety grounds after just 5 years.
Halley III was the first base specifically designed to be able to cope with being buried by the ice. The buildings were prefabricated huts surrounded by steel Armco tubing which helped prevent the movement of the ice from crushing the structures inside. Halley III lasted for around 10 years before it was abandoned (presumably because it was either too deep or was being crushed).
The interesting thing about the old bases is that eventually they tend to pop out the side of the ice shelf. This picture for instance shows Halley III re-emerging 12 years after it was abandoned. As well as getting buried by one metre a year the bases are also moving horizontally by about 1km per year. As the ice shelf flows of the continent and bits break off to form icebergs the old structures are revealed.
Halley IV used a similar design to Halley III and was constructed in 1983. It was made up of four two-storey buildings in a network of interconnected tunnels. It lasted until 1991 when it was replaced by the current station.
When it was built Halley V was a pretty revolutionary design. The original base consisted of three structures all built on jackable legs to allow them to be raised above the snow surface. By keeping the base on the surface Halley V has outlasted all the previous bases (15 years so far) as well as vastly improving the conditions for the people living here.
So if Halley V is so successful, why does it need to be replaced? Well the problem this time isn't the vertical movement, it's the horizontal movement. As we move closer to the coast there is an increased chance that the ice shelf could carve off south of Halley and the whole station float off to sea! To get around the problem the new base will be constructed further inland, and is designed to be relocatable if necessary.
For more information on the history of Halley visit Andy Smith's excellent ZFIDS website.
Posted by simon at 11:03 AM | Feedback (4)