Halley VI in situ

Halley VI: coming in from the cold

British research station Halley VI has now been in operation on the icy wastelands of Antarctica for a year. Climate scientist and explorer Felicity Aston reports on how things have progressed in one of the loneliest and coldest buildings in the world.

Taking my seat on the Russian IIyushin II-76 into Antarctica, I saw a face I recognised. A decade previously I had spent three years living and working as a meteorologist at Rothera, Britain's largest research station in Antarctica. Simon had been a logistics manager at the base, but now he was heading south as a project manager for Galliford Try, the construction company building the UK's newest research station on the continent, Halley VI. With construction limited to Antarctica's 12-week summer season, the build was already into its third year.

When Simon showed me a photograph of the new station I wasn't at first completely sure what I was looking at. The bright blue capsule standing on ski-footed legs looked peculiarly canine as it sat in a landscape of polar wastes. It could have been a CGI still from the latest science-fiction blockbuster.

The extraordinary-looking structure was part of the latest incarnation of Halley Research Station. First established in 1956 for the International Geophysical Year of 1957/58 by an expedition from the Royal Society, Halley has been an operational science facility, year-round, ever since. Situated under the auroral arc, a zone of high geophysical activity, it is ideal for the study of atmospheric sciences and geospace. It was at Halley in 1985 that scientists discovered the seasonal depletion of ozone, which later became known as the Ozone Hole.

The first buildings at Halley were simple wooden huts, which quickly became engulfed by high snow accumulation. Subsequent stations were made of corrugated steel tubing specifically designed to be buried, but eventually these too were crushed by the pressure of the ice. The next station was constructed on a platform with jackable steel legs to be raised clear of the snow. Completed in 1992, Halley V marked a leap forward in the design of polar accommodation.

A moveable research station

However, the station faced another problem. Halley is located on the Brunt Ice Shelf, a sheet of floating ice, 200m thick, that flows from Antarctica's interior and over the sea at a rate of 400m per year. It is a continuous ocean-bound conveyor belt that eventually calves into vast icebergs. Halley V had been moving at a rate of 0.5km per year towards the ice-edge and in 2005 scientists realised that it was in danger of being set adrift by a calving event.

In response, the British Antarctic Survey (BAS), which operates all of the UK's scientific activity in Antarctica, launched an international competition in conjunction with the Royal Institute of British Architects to design Halley VI. Prominent among the design criteria was that the new station had to be fully relocatable: a first for Antarctica. Hugh Broughton Architects, a London-based practice, worked with engineering firm AECOM to develop the winning design.

Their vision for Halley VI was a series of modules connected by flexible insulated bellows, resembling those used to attach train carriages. In fact, the bellows were ultimately manufactured by low-temperature rubber specialist Trelleborg, who more usually supply equipment to link trains in the Arctic. "Starting with standard products and adapting them was a deliberate approach," says architect Hugh Broughton. "BAS was concerned that new technology meant that it would be more likely to malfunction and be expensive to repair."

The image I saw pictured a single module. Each of the seven modules that make up the station sits on four jackable legs, similar to those supporting the platform under Halley V, but they have giant steel skis mounted onto each footing. Measuring 3.9m long and 1.1m wide, the skis have a steel 'centreboard' that can bite into the ice to aid traction and, conversely, a PTFE coating on the underside that prevents the skis 'sticking'.

The ski-fitted legs allow each module to be detached and individually towed to a new location. The 80-tonne, 152m2 modules were designed to be towed by two D5 Caterpillar bulldozers, each mustering 100hp, but BAS has now purchased two Agco Challenger tractors. With 325hp, each tractor has a towing capacity of 30,000kg, which makes station-moving a much quicker process.

"From the outset, reducing the labour requirement of the new station was important," says Broughton. This philosophy applied not just to the horizontal movement of the station but its vertical movement too.

Computerised control systems

The jacking of Halley V was a two-month procedure that required a large team of steelworkers extending and re-welding the steel legs. The new station employs computer-controlled hydraulic rams to do the job. "Each foot is mechanically raised and new snow piled up underneath before it is lowered," explains Broughton. "It takes a couple of weeks for two vehicle operators and one supervisor to complete. Then the entire building is raised in just a few days."

Overall, Halley VI requires 10 fewer people to undertake annual summer maintenance than its predecessors. This is a significant saving not just in manpower but also in the supplies, fuel and energy required to retain personnel in Antarctica.

The legs are circular telescopic tubes, roughly 500mm in diameter, which can withstand the weight of the module as well as the loads created by wind and ice. The integral hydraulic ram in each leg is operated by a computerised control system. Data is extracted from pressure and extension transducers in the hydraulic cylinders and additionally from inclinometer sensors fixed to the structure. The processed data is displayed on portable units in each module of the station so pre-programmed leg movements can be performed.

Climate is everything

In Antarctica, the environment is more than something to be protected; it is a dominating force that governs every decision. The station design underwent months of wind tunnel testing and snow modelling to determine performance in the relentless climate but similarly, detailed scrutiny was applied to the plans for construction. Halley is located 900km from the South Pole with conditions unlike any other building site in the world. Temperatures can plummet as low as -55°C, winds can reach speeds of 100mph and visibility can be as little as a metre.

John Hammerton, operations director for Galliford Try, says: "We needed 70 personnel on site and just getting them there took a lot of planning. It was an expensive and complicated process." Not that getting the components of the station to the site was any easier. The only way to transport cargo to Halley is by ship. Once a year the BAS ship RSS Ernest Shackleton calls at Halley to deliver supplies and materials. There is no coastline and the vessel cannot moor alongside the edge of the Brunt Ice Shelf because of the sheer ice-cliffs that frequently crumble into the sea. Instead, the ship anchors to sea ice that forms beneath the ice-cliffs. The sea ice is no more than a metre thick with a maximum safe bearing capacity of just 9.5 tonnes. "Everything that was unloaded over the side of the ship onto the sea ice had to be split into components that weighed less," explains Hammerton. Each component was then dragged by bulldozers up a snow ramp to the surface of the ice shelf and the Halley site 15km from the ice-edge.

The largest individual component was the prefabricated space frame sub-structure of each module. These 9.5m-wide, 18.5m-long frames were constructed from high-ductility steel to form a fully braced tubular sub-structure. The frames were delivered with temporary transit skis attached because adding the final ski-fitted hydraulic legs would have made them too heavy. "We tried to prefabricate as much as possible. Most of the assembly and testing was done on the dockside in Cape Town," says Hammerton.

Bedrooms, bathrooms, plant rooms and kitchen areas were prefabricated and shipped fully fitted out. Once the hydraulic legs had been fitted, composite timber and steel floor cassettes were installed and the living and working 'pods' secured. Finally, cladding panels were put in place over the entire structure. Individual panels measured up to 10.4m high and 3.5m wide, and were 230mm thick. The original intention was for the cladding to consist of timber structurally insulated panels with an aluminium outer skin. However, a conversation between architect Broughton and the station leader at the French-Italian Concordia Research Station on the Antarctic Plateau led to a change. Concordia is clad in lightweight fibre-reinforced polymer panels (FRP).

"FRP provides a number of advantages," says Broughton. "First, it has a very low coefficient of thermal expansion, ensuring stable joints between the panels. Second, it is suited to the construction of larger panel sizes and does not require an additional 'outer' skin, making construction simpler and quicker. Finally, FRP is well proven in cold environments."

The FRP is formed under vacuum with resin-infused cross fibres running diagonally between the inner and outer skins, which prevents delamination under windloading and the abrasive impact of wind-driven snow and ice. The outer skin has a gel-coat finish over acrylic intumescent paint that is both UV and fire resistant. The result was an envelope with U values of better than 0.113 W/m2K and air infiltration is 0.1m3/m2/hour at 50Pa of pressure, which is 100 times better than current UK building regulation limits.

During the build, cargo lines of materials and tools stretched for more than 4km. Time had to be spent securing and marking items with flags because snowstorms rapidly blew away or concealed anything on the ground. Construction began in 2007 and by April 2012 station personnel moved in and the station underwent its first operational winter.

The austral winter extends from April to October. Halley's complement of 56 summer personnel shrinks to just 15. More than 15,000km from the UK, the 'winterers' are isolated and must be totally self-sufficient.

While the majority of Halley VI is housed in the standard blue modules, there is a central red module, which is much larger and contains all the communal living areas. At 479m2 it features a dining area, gym, areas for music practice, darts and computer games, all arranged around a central atrium.

Broughton admits that this is the part of the project of which he is most proud. "Fusion between architecture and engineering is great but interior design is an important feature too," he says. "The central living space marks a big improvement in the thinking behind Antarctic accommodation. It is less industrial and more hotel lobby."

The emotional wellbeing of the station's inhabitants was considered in a variety of ways; from the warm colour palette of the bedrooms and daylight simulation lamps, to additional humidification to counteract the extremely dry air of Antarctica.

Water in the icy desert

The station needed to be highly energy efficient through minimising consumption rather than altering the energy source. "Renewable energy sources are available in Antarctica," says Peter Ayers of AECOM who was the design team director for the project. "But the robustness of technologies is not yet sufficiently developed or proven to be relied on at Halley."

Halley VI is powered by four 120kW combined heat and power (CHP) engines that run on aviation fuel. The thermal output of each engine is around 25kW (85360BTU/h) with efficiency boosted by diverting excess heat to the station's two water-generating melt-tanks. The melt-tanks are housed within steel shipping containers buried beneath the station so that bulldozers can push snow inside for melting; a huge improvement on previous systems which required snow to be manually shovelled every day.

Even so, producing water remains one of the station's greatest energy demands. The introduction of a vacuum drainage system dramatically cut water wastage through flushing. A standard UK toilet uses 9l of water per flush, while vacuum drainage uses just 1.2l per flush. Overall, water usage at the base has been reduced from 120l per person per day at Halley V to just 20l per person per day at Halley VI. This has contributed significantly to the 7 per cent reduction in fuel consumption per m2 at the new station.

After a successful test winter in 2012, Halley VI was officially opened in February 2013. It has now completed its first full year as an operational science facility. More significantly, Halley V was dismantled and removed, signifying the confidence BAS has in the new station.

With fateful timing, Halley VI promptly faced one of the most demanding of Antarctic trials: a power down. Along with a station fire and life-critical surgery, loss of power at a facility is a nightmare scenario within Antarctica. On 30 July 2014, Halley VI lost electrical and heating power for 19 hours. Following well-rehearsed protocol, the station complement went into action to identify and resolve the cause of the problem. With contingency accommodation in place, none of the winterers were in any danger, but the longer a station is left without power, the greater the damage caused. It transpired that the generator shutdown had been caused by a large coolant leak from an arterial pipe in the heating system.

Having survived the ultimate test, confidence in the new building is greater than ever. The revolutionary design has already influenced other facilities on the continent with Spain and Korea using similar modular structures for their latest Antarctic bases.

"The modular design enables the station to be relocated but also adapted and rearranged depending on its needs," says Ayres. "Historically, the life expectancy for stations at Halley has been about 10 years. The design life for this project is 20 years."

It is perhaps poetic that the modular design which has been central to Halley VI's success as both a design and a construction project will also be fundamental to its eventual decommission. The modules are easily disassembled for easy adherence to Antarctic Treaty rules stipulating that anything taken into Antarctica must be removed. "It was always intended that Halley VI would be a visitor to Antarctica," says Ayres. "Not a permanent resident." 

Felicity Aston read physics and astronomy at UCL and was the senior meteorologist at the Rothera Research Station on the Antarctic Peninsula. She has led several polar expeditions and is the author of three books including her latest, 'Chasing Winter: A Journey to the Pole of Cold'. She was appointed a Member of the Order of the British Empire in the 2015 New Year Honours for services to polar exploration.

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